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You can search the entire site. or go to the recent opinions, or the chronological or subject indices. John's Heating Service v. Lamb (5/10/2002) sp-5572

John's Heating Service v. Lamb (5/10/2002) sp-5572

     Notice:   This opinion is subject to correction  before
     publication  in  the  Pacific  Reporter.   Readers  are
     requested to bring errors to the attention of the Clerk
     of  the  Appellate  Courts, 303  K  Street,  Anchorage,
     Alaska 99501, phone (907) 264-0608, fax (907) 264-0878.



            THE SUPREME COURT OF THE STATE OF ALASKA


JOHNS HEATING SERVICE,        )
                              )    Supreme Court No. S-9042/9052
             Appellant/Cross-Appellee,  )
                              )    Superior Court No.
     v.                       )    3KO-93-553 CI
                              )
MICHAEL A. LAMB and CYNTHIA        )    O P I N I O N
E. JOHNSON-LAMB,              )
                              )    [No. 5572 - May 10, 2002]
            Appellees/Cross-Appellants. )
________________________________)

          Appeal  from the Superior Court of the  State
          of  Alaska, Third Judicial District,  Kodiak,
          John J. Reese, Judge.

          Appearances:  Michael  D.  Corey,   Sandberg,
          Wuestenfeld    &   Corey,   Anchorage,    for
          Appellant.   Sarah J. Tugman, Anchorage,  for
          Appellees.

          Before:    Matthews, Chief Justice, Eastaugh,
          Fabe, Bryner, and Carpeneti, Justices.

          CARPENETI, Justice.

I.   INTRODUCTION

          I.   Michael and Cynthia Lamb sued Johns Heating Service

claiming  that Johns Heating negligently failed to  repair  their

furnace  or to warn the Lambs of its dangerous condition.   Johns

Heating  raised a statute of limitations defense that  the  trial

court  precluded  in a summary judgment order.  The  trial  court

also   rejected   Johns  Heatings  pretrial  challenge   to   the

admissibility  of the testimony of several of the  Lambs  medical

experts.  After trial, the jury returned a verdict against  Johns

Heating,  reduced  by the comparative negligence  of  the  Lambs.

Johns  Heating  appeals  the grant of  summary  judgment  on  its

statute   of  limitations  defense,  the  admission   of   expert

testimony, jury instructions on negligence, the denial of summary

judgment  on causation of Michael Lambs retirement, the grant  of

prejudgment interest on future economic damages, and the validity

of  a  joint offer of judgment.  The Lambs cross-appeal the  jury

instruction on comparative negligence, cross-appeal the admission

of  evidence  of Michael Lambs disability retirement,  and  claim

inconsistency in the verdict.  Because a disputed issue  of  fact

exists  as  to when the statute of limitations began to  run,  we

reverse  the grant of summary judgment and remand that  issue  to

the superior court for further proceedings.  Because our law does

not  allow prejudgment interest on future damages, we strike that

award.   On the issue of whether an unapportioned joint offer  by

joint  offerors is valid to invoke the enhanced interest  penalty

provisions  of  Alaska Civil Rule 68, we conclude  that  such  an

offer  was  valid  in this case.   On all of the  numerous  other

issues on appeal and cross-appeal, we affirm.

II.  FACTS AND PROCEEDINGS

     A.   Facts

          In  August  1991  Michael and Cynthia Lamb  bought  and

moved  into  a problem-plagued house1 in Kodiak.  On  October  15

they  called  Johns  Heating to check on  their  furnace.   Johns

Heating  sent  an  employee,  Tim Galloway,  to  investigate  the

problem.

          The  Lambs  alleged that they told Galloway that  their

furnace was not functioning properly, that the furnace seemed  to

be  circulating  soot throughout their home, and that  they  were

concerned  by  the  persistent smell of fuel in  the  house.   As

evidence  of  the problem, Cynthia showed Galloway Bounce  fabric

softener sheets that she had been inserting in the floor vents to

filter  out  soot  and grime that she suspected the  furnace  was

circulating  throughout  the  house.   The  Lambs  claimed   that

Galloway  did not think the soot-filtering Bounce sheets  were  a

          sign of furnace trouble and that he told Cynthia she needed to do

a better job of cleaning the house.

          Johns  Heating disputed the Lambs version of the facts.

Johns  Heating  claimed that the Lambs informed neither  Galloway

nor  the employee that answered the Lambs telephonic request  for

service  that  they  suspected the furnace was  circulating  flue

gases  or  other  combustion byproducts into  the  living  space.

Neither  of  the business records relating to the  Lambs  service

call  showed that Johns Heating was informed of, or suspected,  a

more serious furnace problem.

          Both parties agreed that all Galloway did was level the

fuel tank and relight the furnace.

          The  Lambs  began to suffer physical effects from  what

they  later alleged was carbon monoxide poisoning caused by their

furnace.  Both said that they started to feel tired and confused,

and that they lacked concentration and memory.

          The Lambs continued to live in the house and to use the

furnace until January 31, 1993.  At that time, they called  Jerry

Cloudy  at  Chase  Plumbing, another furnace repair  and  heating

business  in  Kodiak, to inspect their furnace.  Cloudy  informed

the  Lambs  that  their furnace was probably  circulating  carbon

monoxide  and other flue gases throughout their home and  advised

them  not to use it while they were home until they could get  it

replaced.   The  Lambs had the furnace replaced six  days  later.

However,   they  continued  to  suffer  residual   physical   and

neurological  problems that they attributed  to  long-term,  low-

level   carbon   monoxide  exposure2  from  their  malfunctioning

furnace.

     B.   Proceedings

          The  Lambs  filed suit against a number of  defendants,

including  Johns  Heating, on December 23, 1993.   Johns  Heating

asserted  the  statute of limitations as an affirmative  defense.

Johns  Heating also moved for summary judgment on the statute  of

limitations issue, claiming that its only contact with the  Lambs

          was on October 15, 1991, and that the Lambs did not file suit

until  December 23, 1993, more than two years later.   The  trial

court  denied  Johns  Heatings motion for  summary  judgment  and

granted  the  Lambs  cross-motion for  summary  judgment  without

explanation, precluding Johns Heating from asserting a statute of

limitations defense at trial.

          Johns  Heating also tried to preclude the testimony  of

the  Lambs  medical  experts regarding  chronic  carbon  monoxide

exposure.   However,  the  court denied  Johns  Heatings  motion,

concluding  that [i]n the case of carbon monoxide  exposure,  the

scientific  community  has  not yet  been  able  to  conclusively

measure  specific neurocognitive damages in relation to  specific

amounts  of  exposure.   Lack of specific  information,  however,

cannot  permit  defendant to shield itself from liability.   This

issue  is  for a jury to decide.  The superior court allowed  the

Lambs experts to testify.

          After a week-long trial in July 1998, the jury rendered

a  verdict  for the Lambs.  The jury awarded $810,000 in  damages

for  Michael Lamb and $815,000 in damages for Cynthia Lamb.  Each

award was composed of both past and future damages.  However, the

jury  also  reduced the awards because it found that  both  Lambs

were comparatively negligent in continuing to operate the furnace

even  though they knew or should have known that it was dangerous

and that it was injuring them.  The jury found Michael forty-five

percent at fault for his injuries and found Cynthia forty percent

at  fault for her injuries.  The verdict was accordingly  reduced

by those percentages.

          After   the  jury  returned  its  verdict,  the   Lambs

submitted a proposed order of final judgment containing  interest

calculations  and attorneys fees awards.  The court  adopted  the

Lambs proposed order, which applied an enhanced interest rate  of

15.5%  for  its  computation of the prejudgment interest  on  the

jurys  award.   The  court ordered enhanced prejudgment  interest

because  Johns Heating had not accepted the Lambs pretrial  joint

offer  of  judgment  in  the  amount of  $750,000,  inclusive  of

interest, costs, and attorneys fees.

          Johns  Heating appeals on six issues: (1)  whether  the

superior court erred in granting summary judgment in favor of the

Lambs  on the statute of limitations issue; (2) whether the Lambs

expert testimony on chronic carbon monoxide exposure should  have

been   inadmissible;  (3)  whether  the  jury   instructions   on

negligence were in error; (4) whether the superior court erred in

failing to grant summary judgment that Michael Lambs Coast  Guard

retirement  was  due  to his back injury and not  chronic  carbon

monoxide  exposure;  (5) whether prejudgment interest  on  future

economic damages that are discounted to the time of trial  is  an

impermissible  double recovery; and (6) whether the  Lambs  joint

offer  of  judgment  was invalid to trigger  the  Civil  Rule  68

prejudgment  interest penalty.  The Lambs cross-appeal  on  three

issues:  (1) whether the court erred by giving a jury instruction

on  comparative  negligence; (2) whether  admitting  evidence  of

Michael  Lambs  disability  retirement  violated  the  collateral

source  rule;  and (3) whether the jury rendered an  inconsistent

verdict by failing to award Michael Lamb past economic damages.

III. STANDARD OF REVIEW

          We   review  a  trial  courts  order  granting  summary

judgment de novo.3  We draw all reasonable factual inferences  in

favor  of  the  non-moving party.4  By our  review,  we  seek  to

determine  whether  genuine issues of  material  fact  exist  and

whether  the moving party is entitled to judgment as a matter  of

law.5

          We   review  the  trial  courts  admission  of   expert

scientific evidence for an abuse of discretion.6

          We  review  whether a jury instruction is appropriately

tailored  to  the  case  at hand under the  abuse  of  discretion

standard.7  Whether a jury instruction properly instructs on  the

law, however, is reviewed de novo.8

          Finally, questions of law are reviewed de novo.9

IV.  DISCUSSION

     A.   Summary Judgment Was Not Appropriate Because the Date that

          the Lambs Reasonably Should Have Discovered that They Were Being

          Exposed to Carbon Monoxide Due to Johns Heating Negligence Is a

          Disputed Factual Issue.

          A.   Johns Heating argues that summary judgment was improperly

granted on the statute of limitations issue.  Johns Heating notes

that  whether  the  Lambs had sufficient  information  to  prompt

reasonable  people to conduct an inquiry to protect their  rights

was  in  dispute  when the trial court granted summary  judgment.

The  Lambs counter by arguing that as a matter of law the statute

of limitations did not begin to run until the Lambs had reason to

believe  not only that the furnace was operating poorly but  also

to  suspect that they were injured and that it had injured  them.

The  Lambs conclude that the date on which their cause of  action

accrued  was  therefore January 31, 1993, when  Jerry  Cloudy  of

Chase Plumbing told them the furnace was probably malfunctioning.

The  superior  court apparently agreed with the  Lambs  since  it

granted summary judgment in their favor on this issue.

          Alaska  Statute  09.10.070(a) states that  [e]xcept  as

otherwise   provided  by  law,  a  person  may   not   bring   an

action . . . for personal injury or death . . . unless the action

is  commenced  within two years of the accrual of  the  cause  of

action.10

          The date on which the statute of limitations begins  to

run  is  a  factual  question.11  Because the  question  is  fact

dependent,  summary judgment ordinarily should  not  be  used  to

resolve when a statute of limitations commences.12  Only  in  the

unusual  circumstance  in which there exist uncontroverted  facts

that  determine  when  a reasonable person should  have  been  on

inquiry  notice can a court properly resolve the  question  as  a

matter  of  law.13   Accordingly, we must determine  whether  the

superior  court had before it uncontroverted facts sufficient  to

support its entry of summary judgment.

          1.   The discovery rule provides the legal test as to when the
               statute of limitations began to run on the Lambs negligence
               claim.
               
          Where   an  element  of  a  cause  of  action  is   not

immediately apparent,14 the discovery rule provides the test  for

the date on which the statute of limitations begins to run.15  As

we have explained,

          the statute of limitations does not begin  to
          run   until   the   claimant  discovers,   or
          reasonably   should  have   discovered,   the
          existence  of all elements essential  to  the
          cause  of  action.   Thus we  have  said  the
          relevant   inquiry  is  the  date  when   the
          claimant reasonably should have known of  the
          facts  supporting her cause  of  action.   We
          look to the date when a reasonable person has
          enough information to alert that person  that
          he  or she has a potential cause of action or
          should begin an inquiry to protect his or her
          rights.[16]
          
          Thus,  under the discovery rule there are two  possible

dates on which the statute of limitations can begin to run17 and,

in  some  cases,  a third part to our discovery  rule,  which  we

discuss below.18  The first potential date is the date when [the]

plaintiff reasonably should have discovered the existence of  all

essential elements of the cause of action.19  The second potential

accrual date is the date when the plaintiff has information which

is sufficient to alert a reasonable person to begin an inquiry to

protect his rights.20  As we explained in Cameron v. State, [t]he

dates are different, since the point when the elements of a cause

of  action  are discovered may come after and as a  result  of  a

reasonable  inquiry.21  As we further explained in  Cameron,  the

third  part of the discovery rule comes into play where a  person

makes a reasonable inquiry which does not reveal the elements  of

the  cause of action within the statutory period at a point where

there remains a reasonable time within which to file suit.22   In

those  circumstances, the limitations period is  tolled  until  a

reasonable  person discovers actual knowledge of, or would  again

be prompted to inquire into, the cause of action.23

          The  Lambs argument that their cause of action did  not

accrue until January 1993, when they were informed that they  had

probably  been  exposed  to  carbon monoxide  by  their  furnace,

addresses  the  first potential date provided  by  the  discovery

rule.   That  is, the Lambs argue that their cause of action  did

not accrue until they had actual knowledge of the source of their

injuries.24   Johns Heating argues that the Lambs had information

sufficient  to  alert  a reasonable person to  begin  an  inquiry

before December 22, 1991, or more than two years before the Lambs

had  filed  suit.  Johns Heatings argument addresses  the  second

accrual date possible under the discovery rule.  Accordingly,  we

must  decide  whether the trial court erred by  granting  summary

judgment  when  Johns  Heating produced evidence  supporting  the

contention  that the Lambs had sufficient information  to  prompt

reasonable people to begin an investigation.

          2.   Johns Heating presented sufficient evidence to create a
               genuine issue of material fact as to the inquiry-notice date on
               which the statute of limitations began to run.
               
          1.   Following the inquiry-notice approach under the discovery

rule,   Johns  Heating  suggests  that  it  provided   sufficient

information for a jury to find that the Lambs knew or should have

known that they were being exposed to carbon monoxide as early as

October  15,  1991.   In  the  material  supporting  its  summary

judgment  motion on this issue, Johns Heating presented  evidence

to  support its theory that the Lambs should have known that they

were being exposed to combustion byproducts but took no action to

protect  themselves.  Johns Heating provided evidence  that  even

under  the  Lambs  version of the facts they knew:  (1)  that  an

apparently  malfunctioning furnace was  causing  them  headaches,

prompting  them to call for a repair of the furnace;25  (2)  that

Galloway did not correct the furnace problem because it continued

to  blow  soot  into the house; (3) that during  the  October  15

visit,  Cynthia  showed Galloway corrosion holes in  the  furnace

cabinet, but Galloway did nothing, noting that he might  have  to

tear the furnace apart to figure out what was wrong with it;  (4)

          that Cynthia admitted she knew there was still a problem with the

furnace  after  the  Galloway service  call;  (5)  that  although

Cynthia  cleaned  out  the vents and ducts on  a  fairly  regular

basis,  the  soot problem persisted; (6) that the Lambs  switched

from  the  Bounce sheets to cut-up furnace filters  because  they

thought  furnace filters would do a better job; and (7) that  the

fuel smell persisted.

          Our  holding in Meyer v. State, Department of  Revenue,

Child  Support Enforcement Division, ex rel. N.G.T.26 shows  that

the  evidentiary  threshold necessary to preclude  the  entry  of

summary  judgment is low.  In Meyer, a paternity  proceeding,  we

held  that the putative fathers sworn denial that he had  engaged

in  sexual  intercourse  with the mother  during  the  period  of

conception  was  sufficient  to preclude  the  entry  of  summary

judgment  despite  significant evidence that he  was  the  father

including  the results of a genetic test that suggested  that  he

was the father by a probability of 99.98 percent.27

          The   facts  put  forth  by  Johns  Heating,  and   the

supporting deposition testimony of the Lambs, created  a  genuine

issue  of  material fact as to whether the Lambs  had  sufficient

information  to  constitute inquiry notice  under  the  discovery

rule.   Accordingly, the trial court improperly  granted  summary

judgment to the Lambs on the statute of limitations issue.

          We  remand  the  statute of limitations  issue  to  the

superior  court  for determination as a preliminary  question  of

fact.28   Because the superior court granted summary judgment  on

the  issue,  Johns Heating may have additional evidence  that  it

would have presented at trial.29  In that situation, the superior

court has discretion to hear more evidence on the issue.

          On  remand,  the  superior court must  first  determine

whether   the  Lambs  had  sufficient  information  to  alert   a

reasonable person to begin an inquiry before December  22,  1991.

If the superior court finds that the Lambs were on inquiry notice

before  December 22, 1991, the superior court must also determine

          whether the third part of the discovery rule applies.  If the

superior  court finds that the Lambs were on inquiry  notice  and

the third part does not apply to toll the statute of limitations,

the  Lambs  claim would be barred by the statute of  limitations,

and  the  jury  verdict against Johns Heating  must  be  vacated.

However, if the superior court finds otherwise, the jury  verdict

and  award  should stand subject to our rulings on the  remaining

issues of this appeal.

     B.   The Superior Court Did Not Abuse Its Discretion in Admitting
          the Lambs Expert Testimony.
          
          Johns Heating appeals the superior courts admission  of

the  testimony of the Lambs experts regarding their injuries from

chronic  carbon  monoxide exposure.  Johns Heating  attacks  this

admission of evidence on two fronts.  First, Johns Heating argues

that  the Lambs experts testimony does not meet the admissibility

requirements of State v. Coon30 and lacks sufficient  evidentiary

foundation.   Johns  Heating argues that we  must  at  the  least

remand  this  case so that the trial court can conduct  a  proper

evidentiary hearing under the Coon standard.

          During  the  pendency  of this  case,  we  decided  the

relevant  test and standard procedure by which trial courts  must

evaluate  challenged scientific evidence in State v. Coon.31   In

that decision, we moved away from the previous governing standard

derived  from  Frye v. United States32 and to a standard  derived

from Daubert v. Merrell Dow Pharmaceutical, Inc.33  We adopted the

position that the trial court is the gatekeeper34 responsible for

keeping  out junk science,35 noting that the evidence rules  give

trial  courts  both  the  authority  and  the  responsibility  to

determine the admissibility of such evidence.36

          Our  overall intent in Coon was to continue and clarify

our liberal admissibility standard for expert witness testimony.37

While  we noted that by abandoning Frye we would sometimes  allow

evidence  that had not been generally accepted by the  scientific

community  and exclude evidence that had been generally accepted,

we  also  noted  the  unlikelihood that methodologies  that  were

          admitted under Frye and that remain generally accepted in the

appropriate community will be excluded [under Coon].38   The  net

effect,  then,  should be including more expert  testimony.   The

principal reason for adopting the Daubert standard is to give the

courts  greater  flexibility in determining the admissibility  of

expert testimony, so as to keep pace with science as it evolves.39

          Coon  listed four factors to be considered by  a  trial

court in assessing the admissibility of scientific evidence:

          (1)  whether the proffered scientific  theory
          or   technique   can  be   (and   has   been)
          empirically   tested   (i.e.,   whether   the
          scientific   method   is   falsifiable    and
          refutable);   (2)  whether  the   theory   or
          technique has been subject to peer review and
          publication;   (3)  whether  the   known   or
          potential   error  rate  of  the  theory   or
          technique  is  acceptable,  and  whether  the
          existence   and  maintenance   of   standards
          controls the techniques operation;   and  (4)
          whether  the theory or technique has attained
          general acceptance.[40]

          We  noted in Coon that this standard might also be  met

by  confirmation that the evidence is derived by  the  scientific

method  [or]  .  . . based on scientifically valid  principles.41

Additionally, the Coon requirement may be satisfied by a  showing

that  either  (a) the experts proffered testimony [grew]  out  of

prelitigation  research,  or  (b)  the  experts  research   [was]

subjected to peer review.42

          1.   The  theory that chronic carbon monoxide  exposure
               is  harmful  is  admissible  under  Coon  and  has
               sufficient evidentiary foundation.
               
          Johns Heating attacks the Lambs experts testimony based

on  three  specific shortcomings: (1) although short-term,  high-

concentration  carbon monoxide exposure is known to  be  harmful,

insufficient evidence supports the extrapolation that  long-term,

low-level  exposure is harmful; (2) differential  diagnosis43  is

insufficient  to prove that carbon monoxide exposure  caused  the

Lambs  injuries;  and (3) the Lambs failed to produce  sufficient

foundational evidence that they were exposed to carbon  monoxide.

          Under the flexible Coon test, we review the superior courts

decision for an abuse of discretion.44

          The theory that chronic exposure to carbon monoxide has

harmful  effects  satisfies two of the Coon factors:  the  theory

enjoys  general acceptance and has been published.  All  five  of

the experts, including Drs. McCarthy and Brent for Johns Heating,

agreed  that  chronic carbon monoxide exposure could be  harmful.

Dr. Becker testified more broadly: [C]linicians know that chronic

low-level exposures cause problems in some people.  This  general

acceptance supports reliability.

          Several   publications  on  chronic   carbon   monoxide

exposure  are  available.   The  record  contains  two:  a  paper

entitled Memory Disturbances Following Chronic, Low-Level  Carbon

Monoxide Exposure and the Indoor Air Pollution guide sponsored in

part  by the United States Environmental Protection Agency, which

includes  a table showing the effects associated with  acute  and

less-than-acute  blood  concentrations of  carbon  monoxide.   In

addition,  Dr. Hartlage has recently drafted a paper  on  chronic

carbon  monoxide exposure, which is in the process of peer review

and  publication,  and Dr. Becker testified to the  existence  of

other  papers, case studies of chronic carbon monoxide  exposure.

The  reliability  of  the  theory that  chronic  carbon  monoxide

exposure   is   harmful  is  sufficiently  supported   by   these

publications and its general acceptance.

          Johns  Heating argues that because the threshold  level

at  which carbon monoxide becomes harmful is unknown, the  theory

that  chronic carbon monoxide exposure is harmful is  unreliable.

Johns  Heating  questions the extrapolation from  the  fact  that

acute  exposure  causes  neurological harm  to  the  theory  that

chronic  exposure can also cause harm.  Other courts have  warned

against unwarranted extrapolations and required such evidence  to

be reasonable and scientifically valid.45

          We  conclude that the extrapolation from the fact  that

short-term, high-level carbon monoxide exposures are harmful (and

          sometimes fatal) to the theory that long-term, low-level carbon

monoxide exposures are also harmful is generally reasonable.  And

the   published  case  studies  indicate  that  the   theory   is

scientifically  valid.   The analytical  gap  between  the  known

harmful  acute  exposures  to carbon  monoxide  and  the  unknown

threshold  for harmful lower-level, longer-duration  exposure  is

not  fatal to admission of the Lambs experts.  Empirical  testing

is but one factor in the Coon test.

          [W]hile  precise information  concerning  the
          exposure necessary to cause specific harm  to
          humans  and exact details pertaining  to  the
          plaintiffs  exposure  are  beneficial,   such
          evidence   is   not  always   available,   or
          necessary, to demonstrate that a substance is
          toxic  to  humans given substantial  exposure
          and need not invariably provide the basis for
          an experts opinion on causation.[46]
          
The  fact  that such testing on humans simply cannot be ethically

undertaken  explains  and excuses the lack  of  testing  to  some

extent.   In  this case, the lack of empirical testing  does  not

render the theory so unreliable as to require exclusion.

          Johns   Heating   also  challenges   the   differential

diagnosis methodology by which several of the Lambs experts  came

to  the conclusion that the Lambs were harmed by chronic exposure

to carbon monoxide.

          Johns  Heatings  argument that the trial  court  should

have  excluded the Lambs experts differential-diagnosis testimony

as scientifically unreliable fails because differential diagnosis

is a standard medical methodology.47  A strong majority of federal

circuits   deciding  the  issue  have  allowed  expert  testimony

employing differential diagnosis.48

          While   an   important  aspect  of  assessing
          scientific     validity    (and     therefore
          evidentiary  reliability) is the  ability  of
          other   scientists  to  test  or   retest   a
          proponents  theory,  differential   diagnosis
          involves assessing causation with respect  to
          a  particular individual.  This merely  makes
          it  a  different type of science than science
          designed to produce general theories; it does
          not make it unreliable science.[49]
          
We   decline   to   hold   differential-diagnosis   methodologies

inadmissible in light of the medical communitys daily use of  the

same methodologies in diagnosing patients.50

          Of  course,  [a] differential diagnosis that  fails  to

take  serious account of other potential causes may be so lacking

that  it  cannot  provide  a reliable basis  for  an  opinion  on

causation.51   But  here  that is not the  case.   Here,  doctors

experienced   with   carbon  monoxide  exposure   performed   the

differential   diagnosis,   which   included   making    physical

examinations,  taking  medical history,  and  reviewing  clinical

tests.   In  addition, the diagnosis was bolstered by a  temporal

relationship  between  the  symptoms  and  the  possible   carbon

monoxide   exposure   and   the  discrepancy   between   Cynthias

performance  and  verbal  IQs corresponding  almost  uniquely  to

carbon  monoxide  poisoning.   An  experts  causation  conclusion

should  not  be  excluded because she has  not  ruled  out  every

possible  alternative;  rather,  existing  possible  alternatives

should  affect  the  weight  that  the  jury  gives  the  experts

testimony.52  The Lambs experts theories are sufficiently reliable

for  admissibility under Coon.  At most, Johns Heating is arguing

lack of certainty, but a lack of certainty does not preclude  the

useful application of a scientifically valid method.

          Finally, Johns Heating contends that the Lambs did  not

provide  any  record evidence that they were  exposed  to  carbon

monoxide.  According to Johns Heating, there was not an  adequate

basis either for the experts to opine that the Lambs were exposed

to carbon monoxide or for the jury to make the same finding.

          Although  the Lambs did not produce any direct evidence

that  they were ever exposed to carbon monoxide, such as  ambient

air  measurements  of  carbon monoxide in  their  home  or  blood

samples indicating elevated carboxyhemoglobin levels taken  while

the  allegedly defective furnace was operating, they did  provide

circumstantial  evidence.   For  instance,  they   provided   the

testimonial  evidence  of  Cloudy and Clark  that  an  improperly

          operating furnace with corroded components could introduce carbon

monoxide into a home.  And they provided pictures documenting the

corroded  condition  of  their  furnace.   Thus,  there  was   an

evidentiary  footing from which both the Lambs  experts  and  the

jury  could  build  a logical framework of facts  indicating  the

Lambs were exposed to carbon monoxide.

          2.   The superior court did not commit reversible error by
               failing to hold an evidentiary hearing under the Coon standards
               before admitting the Lambs experts testimony.
               
          Johns Heating asserts that the trial court should  have

conducted  a  more thorough evidentiary inquiry before  admitting

the  Lambs  experts scientific testimony.  Johns  Heating  argues

that the trial court effectively abandoned its gatekeeper role by

failing  to probe the validity and scientific bases of the  Lambs

evidence  when it was challenged in a pretrial motion.  We  note,

however,  that Johns Heating merely filed a motion in  limine  to

preclude the Lambs experts testimony.  Because Johns Heating  did

not  ask  the  superior  court  for an  evidentiary  hearing,  it

effectively waived its right to one.53

          In  addition,  we  conclude that  such  a  hearing  was

unnecessary in this case.  Although a trial court should  conduct

an   evidentiary  hearing  and  perhaps  even  select   its   own

independent  expert witness or appoint an expert advisor  when  a

proper  challenge is brought to the admissibility  of  scientific

evidence or testimony,54 the trial court did not commit error  by

failing  to   conduct  a  hearing here.  Neither  the  scientific

methodology  nor the evidentiary foundation was significantly  in

question in this case.

          In  sum,  the  Lambs experts theories are  sufficiently

reliable   for   admissibility  under  Coon  and  have   adequate

evidentiary  foundation.  Also, the trial court was not  required

to  hold  a  Coon admissibility hearing sua sponte.  Accordingly,

the  trial  court did not abuse its discretion by  admitting  the

testimony of the Lambs medical experts.

     C.   The Superior Court Properly Treated the Lambs Claim as a
          Professional Negligence Claim; It Committed Harmless Error by
     Excluding the Testimony of Qualified Experts on the Standard-of-
          Care Issue.
          
          Johns  Heating  argues that the trial  court  erred  by

deeming  this  a professional negligence case.  This  raises  two

issues.  The first is whether the actions of Galloway, the  Johns

Heating  employee who responded to the Lambs request for service,

should  be held to a standard of care attributable to that  of  a

skilled  furnace  repairperson acting under  like  circumstances.

The  second  issue is whether expert testimony  was  required  to

establish  the  relevant standard of care.   Johns  Heating  also

argues that the superior court abused its discretion by excluding

all  testimony on the standard of care except that of Pat  Clark,

one of the Lambs expert witnesses.

          1.   Because the level of skill and knowledge required of a
               competent furnace repairperson is specific to the skill of
               furnace service and repair, the Lambs claim is one for
               professional negligence.
               
          Johns Heating argues that this case does not fall under

the  rubric  of professional negligence.  We disagree.   A  claim

that a provider of skilled services committed negligence states a

claim of professional negligence.55

          It  is  a  general rule of law that,  when  a
          person holds himself out to the public in any
          particular employment, work, or trade,  there
          is  an implied engagement with those who  may
          employ him that he and his employees in  that
          trade  or  business possess  that  reasonable
          degree  of  knowledge  and  skill  which   is
          ordinarily possessed by others engaged in the
          same  business or trade; and that he and they
          will  perform the services which  he  may  be
          engaged to do, diligently and faithfully, and
          with   that  skill  and  prudence  ordinarily
          possessed  and observed by others engaged  in
          the same or like employment.[56]
          
Courts  have  applied  the professional  negligence  standard  to

trades persons including machinists, electricians, and plumbers.57

Furnace repair is a similar trade.  Thus, the superior court  did

not err by treating this case as one for professional negligence.

          In addition, Johns Heatings argument that this is not a

          professional negligence action is inconsistent with its proffered

Jury Instruction 13.  Modeled after the jury instruction at issue

in Pepsi Cola Bottling Company v. Superior Burner Service,58  Jury

Instruction 13 sets out the standard for professional negligence:

               The  defendant held itself  out  to  the
          public   generally  as  a  qualified  heating
          service  company.  The defendant was required
          to  exercise that degree of skill in handling
          the  job  for  which  it was  called  by  the
          plaintiffs   which   a  reasonably   prudent,
          skilled and qualified heating service company
          would  exercise under the circumstances.   If
          the  defendant failed to use that  degree  of
          care and skill in performing the task, it was
          negligent toward the plaintiffs.[59]
          
          Johns Heatings argument that this language does not set

out  a  professional  standard of care is not  well  taken.   The

instruction explicitly calls for a standard of care that  depends

upon  the  relevant  skill and care that  a  reasonably  prudent,

skilled  and  qualified  heating service company  would  exercise

under  the circumstances, not the skill or care that a reasonably

prudent person would exercise, as would be the case if this was a

claim for ordinary negligence.

          2.   The superior court did not err by limiting the jurys
               consideration of the standard-of-care issue to the evidence
               presented by expert witnesses.
               
          Johns  Heating argues that [i]t is difficult to imagine

less need for expert testimony concerning [the] standard of care.

While  it  is  true  that expert testimony  is  not  required  to

establish  the  standard  of care in all  cases  of  professional

negligence,60  the  trial court did not abuse its  discretion  by

limiting the evidence on the standard of care to the testimony of

the expert witnesses.

          The  trial  court  was  correct  in  ruling  that  only

witnesses with specialized knowledge of the furnace repair  trade

were  competent to testify directly to the standard of care.   We

note  that  under  Alaska Evidence Rule  702,  whenever  a  party

intends  to  offer evidence concerning any scientific, technical,

or other specialized knowledge, the party must establish that the

          witness who will offer this evidence possesses the knowledge,

skill,  experience, training, or education to offer  an  informed

opinion  on the subject.61  We believe that the proper procedures

for  a  furnace  repairperson to follow on  a  service  call  are

sufficiently  technical  that  only  a  person  with  specialized

training,  knowledge,  or experience in the  subject  of  furnace

repair  could  properly  opine on the  matter.   Moreover,  Johns

Heating  points to no other evidence entered into the  record  by

either party that would have assisted the jury in determining the

standard  of  care.62   Accordingly, the  trial  court  correctly

limited  the  jurys consideration of this issue to  the  evidence

provided  by witnesses with specialized knowledge and  experience

in the field of furnace service and repair.

          3.   Jury Instruction 14 improperly excluded relevant expert
               testimonial evidence.
               
          Johns   Heating  argues  that  the  court  abused   its

discretion  by  excluding all testimony on the standard  of  care

except  the  testimony of Pat Clark, the Lambs expert witness  on

furnaces and heating systems.  The superior court instructed  the

jury  to  consider  only  Pat Clarks testimony  in  deciding  the

standard of care:

               In order for you to decide whether there
          was  negligence in this case, you shall first
          decide  what  level of knowledge,  skill  and
          care  other reputable furnace repairmen would
          have  used under similar circumstances.   You
          shall make this decision only on the basis of
          the  opinion offered by Pat Clark, a  furnace
          repairman  who has testified as an expert  on
          the standard of care.[63]
          
          Alaska   Rule   of   Evidence   702(a)   controls   the

admissibility  of  expert  testimony.64   Evidence  Rule   702(a)

explicitly  allows a person with relevant skill,  experience,  or

training  that  forms  the  basis for  specialized  or  technical

knowledge to assist the trier of fact in assessing an issue.   In

Colt  Industries Operating Corp., Quincy Compressor  Division  v.

Frank W. Murphy Manufacturer, Inc.,65 we held that the trial court

abused   its   broad  discretion  by  precluding  the  plaintiffs

          mechanical engineering expert from testifying about an alleged

design  defect in a particular type of switch gauge  because  the

mechanical  device  at  issue  was not  specifically  within  the

witnesss  expertise.66  In Colt Industries,  we  emphasized  that

Evidence  Rule  702  requires simply  that  the  witness  special

knowledge  must  assist  the  trier of  fact  to  understand  the

evidence or to determine a fact in issue.67  We also specifically

rejected  a  reading  of  Evidence Rule 702  that  would  require

expertise in precisely the area upon which the expert proposes to

comment.68

          Here,  both  Cloudy  and  Butler possessed  specialized

knowledge  as  to the heating service business.   Both  men  were

professionals in the heating services business in Kodiak:  Cloudy

had fifteen to twenty years of experience in the heating business

as  well as relevant carbon monoxide training; Butler had twenty-

five  years  of heating service experience in the Kodiak  area.69

The  exclusion of their testimony by Jury Instruction  14  denied

Johns  Heating  a  witness to rebut Clarks assertions  about  the

appropriate  standard of care for a heating service professional.

In  addition,  the exclusion prevented the jury from  considering

relevant testimony from Cloudy that may have been helpful.  Since

there  was  no  rational  distinction to  be  drawn  between  the

relevant training and experience of Clark, Cloudy, and Butler, it

was  an  abuse of discretion for the trial court to instruct  the

jury to ignore the testimony of Cloudy and Butler on the standard-

of-care issue.

          The  superior  courts exclusion of Cloudy  and  Butlers

testimony,  although  erroneous,  was  harmless.   Johns  Heating

summarizes  Butlers  testimony as simply  that  he  believed  Mr.

Galloways  actions were appropriate.  Our examination of  Butlers

testimony does not reveal anything more helpful to Johns Heatings

position.  Since a conclusory statement by an employer  that  his

employees actions were appropriate does not help to substantively

determine  the  applicable standard of care,70 the  trial  courts

          exclusion of this testimony was harmless.   And since our

examination of the record reveals that Cloudys testimony was more

damaging to Johns Heating than it was helpful,71 we determine that

the  courts  instruction to look only to Pat Clarks testimony  on

the standard of care was also harmless.  Accordingly, we will not

disturb the trial courts judgment on the basis of Instruction 14.

     D.   The Trial Court Correctly Refused to Attribute Michael Lambs
          Cessation of Work Solely to His Back Injury.
          
          Johns  Heating also makes two arguments that  challenge

the trial courts legal treatment of Michaels back injury.  First,

Johns Heating asserts that the superior court should have granted

partial summary judgment that Michaels employment with the  Coast

Guard  ended because of his back injury, not his possible  carbon

monoxide   poisoning.   Johns  Heating  notes  the  inconsistency

between   Michaels   position  in  his  Coast  Guard   disability

retirement  proceeding  that his back was the sole cause  of  his

inability  to  work   and his position in this  litigation   that

neurological  deficiencies  from  chronic  exposure   to   carbon

monoxide prevented him from working.

          Although  the  argument made by Johns  Heating  is  not

devoid  of merit, the threshold for opposing summary judgment  is

very  low.72   It is true that the credibility of Michaels  claim

that his employment ended due to neurological deficiencies caused

by  carbon  monoxide  exposure  is  weakened  by  (1)  his  prior

inconsistent  statement, (2) the statements of his  doctors  that

Michael was unable to work due to his neurological deficiency and

(3)  his  interrogatory  answer that he was  too  embarrassed  to

mention  his mental dysfunction.  But the cause of his disability

retirement  is  a  material question  for  the  jury  to  decide.

Accordingly,  we hold that the trial court properly denied  Johns

Heating summary judgment on this issue.

          Second,   Johns   Heating  argues  that  quasi-estoppel

precludes  Michaels claim that his back injury was not  the  sole

cause  of his disability retirement.  Quasi-estoppel precludes  a

party  from  taking  a  position inconsistent  with  one  .  .  .

          previously taken where circumstances render assertion of a second

position  unconscionable.73   We have  recognized  five  relevant

criteria for evaluating a quasi-estoppel claim:

          Among  the  many  considerations  which   may
          indicate  that  an inconsistent  position  is
          unconscionable  and  the doctrine  of  quasi-
          estoppel  should be applied are  whether  the
          party asserting the inconsistent position has
          gained   an   advantage  or   produced   some
          disadvantage through the first position;  the
          magnitude   of  the  inconsistency;   whether
          changed  circumstances tend  to  justify  the
          inconsistency; whether the inconsistency  was
          relied  on by the party claiming estoppel  to
          his   detriment;   and  whether   the   first
          assertion was made with full knowledge of the
          facts.[74]
          
           Our  analysis of the factors leads us to conclude that

quasi-estoppel is inapplicable here.  Michaels doctors  testified

that  he  was  unable  to  work  as  a  firefighter  due  to  his

neurocognitive  disability.  Even Johns Heatings medical  experts

appeared  to  agree.  Michael gained nothing  from  his  original

position  because  he  would have been  eligible  for  disability

retirement  benefits  for either his back or  his  neurocognitive

disability.  With regards to reliance, Johns Heating has conceded

that  the only reliance by Johns Heating on Lambs representations

that  his  back  rendered him incapable to work, [sic]  is  Johns

Heating  tax  dollars which fund that disability retirement.   In

addition,  Michael testified that he did not have full  knowledge

of  the effects of his exposure to carbon monoxide until after he

applied for disability retirement.  His doctors related testimony

noted  that  people with brain injuries often  do  not  recognize

their  injury  and  frequently suffer from denial.   Under  these

conditions,  failing  to argue that his neurocognitive  condition

played  a  part  in  his disability retirement  does  not  render

unconscionable his later argument that it did.  The  trial  court

did not err by allowing Michael to present his claim.

     E.   The Trial Court Erred by Awarding the Lambs Prejudgment
          Interest on the Future Damages Portion of the Jury Award.
          
          Johns  Heating  challenges the trial  courts  award  of

          prejudgment interest on the portion of the jurys  award

attributable  to  future  damages.   Johns  Heating  argues  that

awarding  prejudgment interest on future damages amounted  to  an

impermissible double recovery.

          A  jury  award  for  future damages  is  discounted  to

present  value as of the date of the verdict to reflect the  fact

that  the  damages are made part of a recovery before they  would

otherwise  accrue.   In  this way, the financial  impact  of  the

passage  of  time [is] incorporated into the jurys damage  award,

[and]  any  award  of prejudgment interest on this  amount  would

therefore constitute a double recovery.75  For example, in City of

Whittier v. Whittier Fuel & Marine Corp.,76 we reversed the trial

courts  award of prejudgment interest on future profits that  had

not  yet  accrued  at the time of judgment.77  More  recently  in

Navistar  International Transportation Corp.  v.  Pleasant,78  we

affirmed a trial courts refusal to award prejudgment interest  on

future damages reduced to present value as of the time of trial.79

          Here,  the  court properly instructed the jury  on  the

issue of reducing the Lambs future damages to their present value

in Jury Instruction 22, which provided in part:

          Any  award that you make for future  economic
          loss  must  be equal to the amount  of  money
          that the plaintiff would need to invest today
          so  that  the  total of the  amount  invested
          today  plus future investment earnings equals
          the  amount of the future economic loss  when
          it will occur in the future.
          
(Emphasis in original.)  Given this instruction to set the future

damages  award  as  of  today   the  date  of  the  verdict    no

prejudgment  interest should have been awarded on future  damages

for  the  time between the date the complaint was served and  the

date the verdict was rendered.

          The  superior  court,  however, signed  the  plaintiffs

submitted   final   judgment   order   that   contained   damages

calculations including prejudgment interest awarded on the future

damages portion of the jury verdict.80

          Because  the  award of prejudgment interest  on  future

damages  caused  a  double recovery, the  trial  court  erred  in

accepting  the  plaintiffs form of judgment.   We  remand  for  a

recalculation  without  awarding  prejudgment  interest  on   the

portion of the jury verdict attributed to future damages.

     F.   Enhanced  Prejudgment Interest Was  Warranted  in  this

          Case.

          Johns  Heating  argues that the trial  court  erred  by

awarding an enhanced rate of prejudgment interest on the  damages

award.   Johns  Heating cites Brinkerhoff v. Swearingen  Aviation

Corp.81  as  authority for the proposition that joint  offers  of

judgment   present   apportionment   issues   that   make    them

inappropriate for the penalty provision of Civil Rule 68.82   But

Brinkerhoff involved an offer made to joint offerees by a  single

offeror.    The   offer   in   that   case   was   unapportioned.

Apportionment  difficulties  are  intrinsic  to  cases  involving

unapportioned joint offers because the offerees must agree as  to

how  proceeds  are  to be divided (or how the responsibility  for

payment should be divided when the offerees are defendants).   In

Taylor  Construction Services, Inc. v. URS Co.,83  Chief  Justice

Rabinowitz, writing for an equally divided court, identified  two

factors that should be analyzed in deciding whether a joint offer

should trigger Rule 68 penalties in the context of an offer  made

by joint offerors to a single offeree.84  First, if the offer was

inclusive  of all the relationships among the parties  and  their

conflicting claims,85 and second, if no apportionment  difficulty

existed,86 the unaccepted offer could trigger Rule 68 penalties.87

We adopt the Taylor dispositional opinions approach today.

           Applying  the  Taylor  factors, we conclude  that  the

unapportioned joint offer in the instant case was a valid Rule 68

offer  of  judgment.   First,  there  is  no  question  that  the

unapportioned  offer  was inclusive of all of  the  relationships

among the parties and their conflicting claims.  That is, had the

offer  been  accepted, all claims between the parties would  have

been  resolved.   Second, no apportionment  difficulties  existed

since the offeree, Johns Heating, was a single entity.

          The judgment finally rendered against Johns Heating  in

favor  of the Lambs was not more favorable to Johns Heating  than

the offer.  Under these circumstances, the superior court did not

err in applying Civil Rule 68s penalty provisions.

     G.   The Superior Court Did Not Abuse Its Discretion by Giving a
          Jury Instruction on Comparative Negligence.
          
          On  cross-appeal, the Lambs challenge the trial  courts

jury instruction on comparative negligence.  The Lambs argue that

no evidence supported the jury finding of comparative negligence.

The Lambs also argue that the instruction given was ambiguous and

unclear.  We reject both arguments.

          1.   The legal preclusion of comparative negligence in medical
               malpractice cases does not extend to the relationship between
               homeowners and furnace repairpeople.
               
           The  Lambs  argue  that  the trial  court  abused  its

discretion by instructing the jury on comparative negligence when

there  was  no  evidence  to  support a  finding  of  comparative

negligence.  The Lambs primarily argue that they were entitled to

rely  absolutely on Galloways alleged assurances of  safety.   To

support  this notion, the Lambs cite a number of cases precluding

comparative negligence instructions when patients relied  on  the

advice of their physicians.

          This  theory fails for two reasons.  First,  a  factual

dispute  existed  regarding whether Galloway had  notice  of  the

allegedly dangerous condition of the furnace and whether he  ever

assured  Cynthia  Lamb  that there was nothing  to  worry  about.

Thus,  the  jury  had  to decide whether the  furnace  was  in  a

defective condition and whether Galloway should have noticed  its

defective  condition.  Second, the physician-patient  cases  that

preclude  a  finding  of  comparative  negligence  to  reduce   a

plaintiff-patients award against his or her doctor do  not  apply

in  the  context  of a repairperson and a homeowner.   A  furnace

repairperson  is  not  a  doctor; the  asymmetry  of  information

crucial  to  the  doctrine  that  there  can  be  no  comparative

negligence by a medical patient  does not exist between a furnace

repairperson  and a homeowner.  Accordingly, the  superior  court

did not abuse its discretion by giving the comparative negligence

instruction.

          2.   The jury instruction on comparative negligence was not
               ambiguous or unclear.
               
          The  Lambs  also  assert that the jury  instruction  on

comparative  negligence was ambiguous and unclear  and  that  any

findings  under it were not supported by evidence.  The  relevant

instruction, Jury Instruction 30, provides:

               I will now define negligence for you, as
          it may apply to the Lambs conduct.  The Lambs
          were comparatively negligent if:
               1)   the  furnace  was  in  a  dangerous
          condition;
               2) either Mike or Cynthia Lamb knew that
          the furnace was in a dangerous condition;
               3)  either  Mike  or  Cynthia  used  the
          furnace; and
               4) the use of the furnace legally caused
          damage   to  the  person  who  knew  of   the
          dangerous condition.[88]
          
The  Lambs  contend that a lack of connecting ands   between  the

three  elements of the four-element instruction probably confused

the  jury.   This contention is frivolous.  The  construction  in

which  only the last element of a list is joined by an and  is  a

standard construction of English prose.  In this form, the and is

read  in  between all the elements of the list, although it  only

appears  prior  to the last element.  Since a lack of  connecting

ands   comprises the Lambs only contention that Jury  Instruction

30 was ambiguous, we reject this argument.

     H.   The Superior Court Correctly Allowed the Jury to Consider
          Evidence of Michaels Disability Retirement Because the Collateral
          Source Rule Did Not Apply.
          
          A.   The Lambs appeal the superior courts admission of evidence

regarding  Michaels Coast Guard disability retirement, contending

that  admission  of  the evidence violated the collateral  source

rule.  We disagree.

          The  collateral source rule serves two roles in Alaska.

First, it prohibits the reduction of a plaintiffs damages when he

[or she] has received compensation from another source.89  Second,

it  precludes  the introduction of evidence of other compensation

on  the theory that such evidence would affect the jurys judgment

unfavorably  to  the  plaintiff on the issues  of  liability  and

damages.90  But evidence of benefits provided to the plaintiff by

an  independent party may be admissible if offered for a  purpose

other than the diminution of the plaintiffs damages.91

          We  are skeptical of the rules applicability in a  case

where  the benefits were ostensibly obtained as the result of  an

entirely  separate injury, as is the case here.  But we need  not

decide  this issue, because Michael sought and obtained  a  Coast

Guard disability retirement on the basis of a bad back.  When  he

later   claimed  that  his  neurological  condition  caused   his

inability  to work, Johns Heating was entitled to defend  on  the

ground  that this claim was inconsistent with the earlier  claim.

While this evidence was harmful to Michael, it was presented  for

reasons  independent of damage reduction.92  The trial court  did

not  violate the collateral source rule by admitting evidence  of

Michaels disability retirement.

     I.   The  Lambs Waived Their Challenge to the Jurys  Special
          Verdict that Found that Michael Lamb Did Not Suffer Any Past
          Economic Damages Because They Failed To Present that Argument
          Before the Jury Was Discharged.
          
          The  Lambs  also argue that the jury had no evidentiary

basis  on which to deny Michael past economic damages.  The Lambs

contend  that  the only evidence on the matter was their  experts

testimony  and that the experts testimony was that Michaels  past

economic  damages  amounted  to  $167,270.   The  Lambs  argument

amounts to one that the jurys verdict was inconsistent because it

compensated   Michael  for  past  non-economic  damages,   future

economic damages, and future non-economic damages, but failed  to

award Michael anything for past economic damages.93

          An  inconsistent verdict argument must be raised before

          the jury is dismissed.94  The Lambs did not present this issue to

the  superior  court  before the jury was dismissed.   The  Lambs

therefore  waived  the  argument  that  the  jurys  verdict   was

inconsistent and cannot bring it for the first time here.95

V.   CONCLUSION

          Because  there was a genuine issue of material fact  as

to  whether  the Lambs had sufficient information  to  constitute

inquiry notice under the discovery rule, we must VACATE the grant

of  summary  judgment  on the statute of  limitations  issue  and

REMAND  for  further proceedings on this issue.  Because  it  was

error to award prejudgment interest on the portion of the damages

attributable  to future damages, we REVERSE that portion  of  the

judgment.   On remand, if the superior court finds  in  favor  of

Johns  Heating  on  the statute of limitations  issue,  the  jury

verdict  and  award  in  the Lambs favor  shall  be  vacated  and

judgment  entered  in favor of Johns Heating.   If  the  superior

court  finds  in favor of the Lambs on the statute of limitations

issue,  the jury verdict and award shall stand, but the  superior

court  shall recalculate the prejudgment interest at the standard

rate  without awarding interest on the future damages portion  of

the jury award.  In all other respects, we AFFIRM the judgment of

the superior court.

                    OPINION - SUPREME COURT

                    APPROVAL FOR PUBLICATION

JOHNS HEATING SERVICE,

               Appellant/Cross-Appellee,
                                             DATE:  5/3/02
     v.
                                             CASE:  S-9042/9052
MICHAEL A. LAMB and CYNTHIA E. JOHNSON-LAMB,

               Appellees/Cross-Appellants.
_________________________________________________________________

Proofed by:  /s/ R.Tromble          /s/ R.McFarland/Blair Marlowe

Approved by:  /s/ Walter L. Carpeneti
               Justice

CONCURRING OPINION(S):  NO
     Justices:

DISSENTING OPINION(S):  Yes NO
     Justices:   Eastaugh

COSTS  AND  ATTORNEY'S FEES: Each side to bear its own costs  and

fees.

SPECIAL  INSTRUCTIONS: Hold for receipt of dissent  approved  for

publication.

RETAIN JURISDICTION:


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Op. No. 5572, May 10, 2002.

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_______________________________
     1     We  reviewed previous litigation brought by the  Lambs
against other defendants regarding this house in Brigdon v. Lamb,
929 P.2d 1274 (Alaska 1997).

     2     We  will refer to long-term, low-level carbon monoxide
exposure   with  the  shorthand  terms  chronic  carbon  monoxide
exposure or chronic exposure.

     3     United  Airlines, Inc. v. Good Taste, Inc.,  982  P.2d
1259,  1262  (Alaska 1999) (citing West v. City of St. Paul,  936
P.2d 136, 138 (Alaska 1997)).

     4    Id.

     5    Id.

     6    State v. Coon, 974 P.2d 386, 398 (Alaska 1999).

     7     Power Constructors, Inc. v. Taylor & Hintze, 960  P.2d
20, 29 (Alaska 1998).

     8    Id.

     9    Guin v. Ha, 591 P.2d 1281, 1284 n.6 (Alaska 1979).

     10    AS 09.10.070(a).

     11    Gudenau & Co. v. Sweeney Ins., Inc., 736 P.2d 763, 767
(Alaska 1987).

     12    Palmer v. Borg-Warner Corp., 818 P.2d 632, 634 (Alaska
1990);  Mine  Safety  Appliances v. Stiles,  756  P.2d  288,  292
(Alaska  1988) (citing Russell v. Municipality of Anchorage,  743
P.2d 372, 375-76 & n.11 (Alaska 1987)).

     13     Palmer, 818 P.2d at 634; see Mine Safety, 756 P.2d at
292 (citing Russell, 743 P.2d at 375-76 & n.11).

     14    The date on which the statute of limitations begins to
run  is  usually  the date on which the plaintiff incurs  injury.
Russell,  743 P.2d at 375 (quoting Gudenau, 736 P.2d at  766-67).
Injury often occurs simultaneously with the corresponding act  of
negligence  that  causes it.  However, when  the  injury  is  not
apparent  at  the time of the negligent act, the  discovery  rule
applies. Pedersen v. Zielski, 822 P.2d 903, 906-07 (Alaska 1991).

     15    Pedersen, 822 P.2d at 907.

     16     Mine Safety, 756 P.2d at 291 (internal editing  marks
and citations omitted).

     17     Waage v. Cutter Biological Div. of Miles Lab.,  Inc.,
926  P.2d 1145, 1148 (Alaska 1996) (quoting Cameron v. State, 822
P.2d  1362,  1366  (Alaska  1991));  see  also  Sopko  v.  Dowell
Schlumberger, Inc., 21 P.3d 1265, 1271 (Alaska 2001).

     18    Cameron, 822 P.2d at 1367.

     19    Id.

     20    Id.

     21     Cameron,  822  P.2d at 1366.  The  earliest  possible
inquiry-notice date of accrual was October 15, 1991  the date  of
the  allegedly  negligent act of Galloway.  The  latest  possible
actual-notice date was January 31, 1993  the date Cloudy informed
the  Lambs  that their furnace was probably malfunctioning  in  a
dangerous fashion.

     22    Id. at 1367.

     23    Id.

     24    We note that this case presents a new variation on the
application  of  the discovery rule, in that here the  plaintiffs
were  arguably  aware  of  the negligent  act  and  its  possible
consequences and were therefore required to inquire in  a  timely
manner into whether they were being injured.  Previously, we have
addressed  situations in which either the injury  and  its  cause
were  unknown,  or the injury was known, but its cause  was  not.
Pedersen  v.  Zielski, 822 P.2d 903, 907 (Alaska 1991).   But  in
Pedersen we made clear that the discovery rule is broad enough to
cover  other undiscovered and reasonably undiscoverable  elements
of the cause of action.  Id.

     25     At  his deposition, Michael Lamb was asked,  Did  you
discuss  with  Cynthia why you needed to have a  heating  service
person  come  out  and look at your furnace?  He responded,  Yes,
because  I  was  sitting up there getting really  bad  headaches.
This  exchange  was  provided to the superior  court  during  the
briefing  on  Johns Heatings motion for summary judgment  on  the
statute of limitations issue.

     26    994 P.2d 365 (Alaska 1999).

     27    Id. at 368.

     28     See Pedersen v. Zielski, 833 P.3d 903, 907 n.4 &  908
(Alaska  1991)  (Questions  concerning  the  application  of  the
discovery  rule that are genuine issues of material fact  .  .  .
must  be resolved at an evidentiary hearing.) See also Decker  v.
Fink,  422  A.2d  389,  394 (Md. Spec. App.  1980)  ([T]he  judge
becomes   the   factfinder  for  purposes  of   determining   the
applicability of the statute of limitations . . . .); Shillady v.
Elliot  Community  Hosp.,  320 A.2d 637,  639  (N.H.  1974)  (The
discovery   rule   .   .  .  [is]  based  on  certain   equitable
considerations[, which] . . . require that the interests  of  the
opposing parties be identified, evaluated and weighed in arriving
at  a proper application of the statute.  The interpretation  and
application  of a statute of limitations is traditionally  within
the  province  of  the court . . . .  This determination  by  the
court  should  be  made  ordinarily at a preliminary  hearing  in
advance  of  trial . . . .); Lopez v. Swyer, 300  A.2d  563,  567
(N.J. 1973).

     29    [T]he party opposing summary judgment need not produce
all of its evidence but instead must only show the existence of a
genuine  factual dispute.  Meyer, 994 P.2d at 367  (citing  Totem
Marine Tug & Barge, Inc. v. Alyeska Pipeline Serv. Co., 584  P.2d
15, 25 (Alaska 1978)).

     30    974 P.2d 386 (Alaska 1999).

     31     We  assume  without deciding that Coon  applies  here
because  both  of  the  parties argued, and  the  superior  court
apparently  decided,  this issue under the  standard  adopted  in
Coon.

     32    293 F. 1013 (D.C. Cir. 1923).

     33    509 U.S. 579 (1993).

     34    Coon, 974 P.2d at 395.

     35    Id. at 396-97.

     36    Id. at 393.

     37    Id.

     38    Id. at 398.

     39    Id. at 399.

     40    Id. at 395.

     41     Id.  (quoting  Daubert v. Merrell Dow  Pharm.,  Inc.,
(Daubert IV), 43 F.3d 1311, 1316 (9th Cir. 1995)).

     42     Id.  (quoting Jay P. Kesan, An Autopsy of  Scientific
Evidence  in  a  Post-Daubert World,  84  Geo.  L.J.  1985,  2003
(1996)).

     43     Differential diagnosis, or differential etiology,  is
the  determination of which of two or more diseases with  similar
symptoms  is  the one from which the patient is suffering,  by  a
systematic  comparison and contrasting of the clinical  findings.
Kannankeril  v. Terminix Intl, Inc., 128 F.3d 802, 807  (3d  Cir.
1997) (quoting Stedmans Medical Dictionary 428 (25th ed. 1990)).

     44    Coon, 974 P.2d at 398.

     45     Moore v. Ashland Chem., Inc., 151 F.3d 269, 279  (5th
Cir.  1998); Daubert v. Merrell-Dow Pharm., Inc., 43  F.3d  1311,
1319 & n.11 (9th Cir. 1995) (on remand).

     46    Westberry v. Ab, 178 F.3d 257, 264 (4th Cir. 1999).

     47     Westberry,  178 F.3d at 262; Baker v.  Dalkon  Shield
Claimants  Trust,  156 F.3d 248, 252-53 (1st Cir.  1998);  In  re
Paoli R.R. Yard PCB Litigation, 35 F.3d 717, 758 (3d Cir. 1994).

     48    Baker, 156 F.3d at 252-53; Zuckowicz v. United States,
140  F.3d 381, 385-87 (2d Cir. 1998); Heller v. Shaw Indus.,  167
F.3d  146, 154, 156-57 (3d Cir. 1999); Kennedy v. Collagen Corp.,
161  F.3d 1226, 1228-30 (9th Cir. 1998); Ambrosini v. Labarraque,
101  F.3d  129, 140-41 (D.C. Cir. 1996).  Only the Fifth  Circuit
differs.   In Moore v. Ashland Chemical, Inc., 151 F.3d 269  (5th
Cir.  1998), the court concluded that the district court did  not
abuse  its  discretion in excluding expert testimony on causation
using   differential  diagnosis  because  the  expert   had   not
previously treated a patient with the same chemical exposure  and
had  no scientific support for the general theory that any  level
of  exposure to the chemical would cause the diagnosed condition.
Id.  at 277-79.  The situation here is not comparable because the
Lambs  experts  all  have  experience  treating  carbon  monoxide
exposure  and because acute carbon monoxide exposure is known  to
cause brain damage.

     49    In re Paoli R.R. Yard PCB Litigation, 35 F.3d at 758.

     50    Benedi v. McNeil-P.P.C., Inc., 66 F.3d 1378, 1384 (4th
Cir. 1995).

     51    Westberry, 178 F.3d at 265.

     52    Heller, 167 F.3d at 157; Westberry, 178 F.3d at 265.

     53     Matter of C.L.T., 597 P.2d 518, 522 (Alaska 1979) (By
consenting  to  certain procedures or by  failing  to  object  to
others,  a  party  may  waive  those rights  which  are  arguably
encompassed within due process guarantees.).

     54    State v. Coon, 974 P.2d 386, 396 (Alaska 1999).

     55    W. Page Keeton et al., Prosser and Keeton on the Law of
Torts   32, at 185-86 (5th ed. 1984); see, e.g., State, Dept   of
Natural Res. v. Transamerica Premier Ins. Co., 856 P.2d 766,  772
(Alaska 1993) (stating that [a] design professional has a duty in
tort  to exercise reasonable care, or the ordinary skill  of  the
profession ) (quoting Moloso v. State, 644 P.2d 205, 217  (Alaska
1982)).

     56     Pusey  v.  Webb,  47 A. 701, 702 (Del.  Super.  1900)
(applying the professional negligence standard to a blacksmith).

     57    Person v. Cauldwell-Wingate Co., 187 F.2d 832 (2d Cir.
1951); Arkansas Machine & Boiler Works v. Moorhead, 205 S.W.  980
(Ark.  1918); Stafford v. Gowing, 18 N.W.2d 156 (Ia. 1945).   See
also  Jerry  L.  Moore, Liability of Artisans and  Tradesmen  for
Negligence,  in  Professional Negligence 309, 310-11  (Thomas  G.
Roady, Jr. & William R. Andersen eds., 1960).

     58    427 P.2d 833, 841 (Alaska 1967).

     59    Jury Instruction 13 (emphasis added).

     60    Johnson & Higgins of Alaska Inc. v. Blomfield, 907 P.2d
1371,  1374  (Alaska 1995) (While expert testimony  is  generally
required  in  medical  malpractice cases, it  is  not  a  general
requirement of all professional negligence actions, especially in
non-technical  situations  where negligence  is  evident  to  lay
people.  )  (quoting Kendall v. State, 692 P.2d 953, 955  (Alaska
1984)).

     61    Ballard v. State, 955 P.2d 931, 941 (Alaska App. 1998)
(internal quotation marks omitted) (quoting Alaska R. Evid. 702).

     62      Johns  Heating  does  argue  that  the  trial  court
improperly excluded from the jurys consideration the testimony of
John  Butler.   We address that argument below.  See  infra  Part
IV.C.3.

     63    Jury Instruction 14.

     64    Alaska Rule of Evidence 702(a) provides:

               If   scientific,  technical,  or   other
          specialized knowledge will assist  the  trier
          of  fact  to  understand the evidence  or  to
          determine   a  fact  in  issue,   a   witness
          qualified  as an expert by knowledge,  skill,
          experience,   training,  or  education,   may
          testify thereto in the form of an opinion  or
          otherwise.
          
     65     822 P.2d 925 (Alaska 1991) (superseded by statute  on
other grounds).

     66    Id. at 932.

     67    Id. (quoting Norris v. Gatts, 738 P.2d 344, 350 (Alaska
1987)).

     68    Id.

     69    By comparison, Clark had twenty-seven years of heating
service experience.

     70    See generally Kraus v. Newton, 542 A.2d 1163, 1167-68 &
n.4 (Conn. App. 1988) (affirming trial courts instruction to jury
that the employers statement that every employee should use great
care  in  the  performance of his duties was not the standard  of
care  that  plaintiff was required to use but was an  appropriate
factor  to  consider  in  determining  whether  plaintiff   acted
reasonably).

     71    For example, Cloudy testified as follows:

          Q:   Do  you  as a furnace repairman  concern
               yourself  with the possible  release  of
               carbon monoxide into a home . . .
          A:   Yes, you do.
          Q:   . . . from a furnace?
          A:   You sure do.
          Q:   Is  that  an important consideration  to
               you?
          A:   More so all the time.
               
     72     Meyer  v.  State,  Dept  of  Revenue,  Child  Support
Enforcement  Div., ex rel. N.G.T., 994 P.2d 365,  367-68  (Alaska
1999), discussed supra at 11.

     73     Jamison v. Consolidated Util., Inc., 576 P.2d 97, 102
(Alaska 1978).

     74    Id. at 102-03.

     75    Sebring v. Colver, 649 P.2d 932, 936 (Alaska 1982).

     76    577 P.2d 216 (Alaska 1978).

     77    Id. at 226.

     78    887 P.2d 951 (Alaska 1994).

     79    Id. at 959-60.

     80     The jury awarded Michael Lamb $45,000 in past damages
and  $765,000 in future damages.  A forty-five percent  reduction
to  account for Michaels comparative negligence yields $24,750 in
past  damages  and  $420,750 in future damages.   The  plaintiffs
calculated prejudgment interest on the full award of $445,500  at
an  annual  interest rate of 15.5% for the 1,680-day period  from
the  date  the complaint was filed until the date of the verdict,
which  resulted  in a prejudgment interest award of  $317,830.68.
The  correct calculation, applying prejudgment interest  to  only
the   past   damages  award,  yields  $17,657.26  in  prejudgment
interest.   Thus,  the  total  judgment  for  Michael  should  be
$463,157.26,  not  the  $763,330.68  awarded.   The   prejudgment
interest award to Cynthia is similarly miscalculated.

     81     663  P.2d 937, 943 (Alaska 1983).  In Brinkerhoff  we
stated  that [a]lthough problems of apportionment may not  always
be  present, such difficulties are prevalent enough to warrant  a
general  exclusion of joint offers from the penal cost provisions
of Rule 68.  Id.

     82    Former Alaska R. Civ. P. 68(b), which applies to cases
filed before August 7, 1997, provides, in relevant part:

          If the judgment finally rendered by the court
          is not more favorable to the offeree than the
          offer, the prejudgment interest accrued up to
          the  date  of  judgment is entered  shall  be
          adjusted as follows:
          
          . . . .
          
               (2)   if   the  offeree  is  the   party
          defending  against  the claim,  the  interest
          rate   will   be  increased  by  the   amount
          specified in AS 09.30.065.
          
     83    758 P.2d 99 (Alaska 1988).

     84    Id. at 102.

     85     This phrase means that [t]he settlement offer clearly
indicated all claims between the parties would be resolved if the
offer were accepted.  Id.

     86    Id. (internal quotation marks omitted).

     87    Id.

     88    Jury Instruction 30.

     89     Tolan  v. ERA Helicopters, Inc., 699 P.2d 1265,  1267
(Alaska 1985).

     90    Id.

     91    Id. at 1268.

     92    See id.

     93     See, e.g., McCubbins v. State, Dept of Natural  Res.,
Div.  of  Parks  and Recreation, 984 P.2d 501, 506 (Alaska  1999)
([T]he jurys verdict awarding damages for future medical expenses
but  not  for  diminished  earning capacity  was  inconsistent.);
Fancyboy  v.  Alaska Village Elec. Co-op., Inc., 984  P.2d  1128,
1135   (Alaska  1999)  (affirming  superior  courts  refusal   to
reinstate  as  inconsistent a jury verdict which found  that  the
defendants  negligence was the cause of the  plaintiffs  injuries
but  which  failed  to  make any award for  medical  expenses  or
non-economic damages).

     94    Nelson v. Progressive Corp., 976 P.2d 859, 863 (Alaska
1999) ([A] litigant waives his right to challenge the consistency
of  a  jurys verdict if he fails to raise the issue and move  for
resubmission prior to the jurys discharge.).

     95    Id.