Documents
Resources
Learning Center
Upload
Plans & pricing Sign in
Sign Out

Ventilation Considerations in Areas with Elevated Ozone Levels

VIEWS: 2 PAGES: 38

									EVIDENCE FOR AMBIENT OZONE’S
IMPACT ON BUILDING OCCUPANT
           HEALTH
2008 National Air Filtration Association, Technical Seminar
                       Memphis TN,
                        April 17, 2008




                    Michael G. Apte
               Indoor Environment Department
            Lawrence Berkeley National Laboratory
      Acknowledgements

 U.S. Environmental Protection Agency

National Institute for Occupational Safety
                 and Health

       US Department of Energy
                What is BASE?
Building Assessment Survey and Evaluation Study
• Cross-sectional study designed to define key
  characteristics of indoor air quality (IAQ) in 100 public
  and commercial office buildings across the
  continental U.S.
• To fill a major data gap regarding indoor air quality in
  office buildings
      What Were the Goals of
        the BASE Study?
• Collect baseline data characterizing public and
  commercial office buildings
• Examine relationships among parameters and
  between parameters and occupants’ perceptions
  and symptoms
• Establish information on important indoor air
  parameters for policy decisions and guidance
  development
• Assist in standardizing methodology and protocols
  for investigations
• Enable the scientific and professional communities
4
  to advance knowledge and improve practices
      BASE Study Design
• Designed through a series of workshops of 50 national
  experts
• Country divided into 10 climatic regions
• Region identified for study in either winter or summer
    Geographic Range

• 25 States
• 37 Cities
  – 52 Summer buildings
  – 48 Winter buildings
• Variation
  – South Dakota: -18 oF (-28 oC)
  – Arizona: 108 oF (42 oC)
  Conducting the BASE Study
• Cities of 100,000 or greater population
  identified in each region
• City randomly selected for study
• Office Building
   –Atleast 50 employees >20 hrs./week
   –No highly publicized IAQ problems


• Test space
   –At   least 50 employees >20 hrs./week (needed >25 for
   questionnaire)
   –Served by no more than 2 air handling units
   –No more than three floors
   –Environmental sampling at three randomly selected indoor
   sites and one outdoor site close to outdoor air intake
BASE Study Schedule
     BASE Study Core Parameters
ENVIRONMENTAL         BUILDING        HVAC            OCCUPANT
MEASURES              CHARACTERISTICS CHARACTERISTICS QUESTIONNAIRE

• Temperature         • Use                  • Specifications       • Work Place
• Relative Humidity   • Occupancy            • Filtration             Characteristics
• Carbon Dioxide      • Physical Location    • Air Cleaning
• Carbon Monoxide     • Ventilation Equip.   • Humidification       • Health and
• Sound               • Construction         • Maintenance            Well-Being
• Light               • Outdoor Sources      • Inspection Sched.
• Particles           • Smoking Policy       • Supply Air Flow      • Work Place
• VOCs                • Water Damage         • Outdoor Air Intake     Environmental
• Formaldehyde        • Fire Damage          • % Outdoor Air          Conditions
• Biologicals         • Renovation           • Supply Air Temp.
• Radon               • Pest Control         • Supply Air RH        • Job
                      • Cleaning Practices   • Exhaust Air Flow       Characteristics
    Ownership of BASE Buildings
              (n=100)
    • Private & Commercial: 41
    • Academic:             15
    • Government:           44
      – Local:     15
      – County:     9
      – State:     13
      – Federal:    7

8
 Building Representativeness

• Using DOE Survey as a basis for
  comparison, the BASE buildings
   – represent the largest 11% of US office
     buildings and
   – represent the office buildings where
     73% of US office workers work
         Building Related Symptoms
          from BASE Survey (BRS)
       Health effects which are linked to time
        spent in a building but to no specific
                    known cause
                Building Related                           Examples
                   Symptom                        – headache, fatigue
                                                  – dry eyes, sore throat, nose/sinus
                                                    congestion
Occurs for at least 4       Occurs at least 1-3   – tight chest, sneeze, shortness of
      weeks                  times per week         breath, cough, wheeze


              Improves when away
            from work environment
             BRS in Analyses
• Lower Respiratory
  – Tight chest, shortness of breath, cough, wheeze
  – LR: ≥1 of the above symptoms
• Mucous Membrane
  – Dry eyes, sore throat, nose/sinus, sneeze
  – MM: ≥ 1 of the above symptoms
• Fatigue/Tiredness - Concentration Difficulty
• Dry Skin
• Headache
                   Symptom Prevalence (%)




               0
                   5
                         10
                                15
                                      20
                                            25
        LR


  C
   ou
     gh



        U
         R

D
 ry
      Ey
         es


   FT
     C
          N

 D
  ry
       Sk
          in
H
 ea
   da
     c   he
                                                 BASE Study BRS Prevalence
             Sensitive Individulals
• Analysis Variable “Sensitive”
• One or more of the following from Occupant Survey
• Previously doctor diagnosed
  –   Asthma
  –   Allergies/Hayfever (mold,dust, pollen)
  –   Eczema
  –   Migraine
• Self diagnosed sensitivity
  – tobacco smoke
                    Statistical Tools
• Multivariate Logistic Regression (MLR)
   – “Is one population experiencing more illness than another
     population?”
   – Output: Odds Ratio (OR)
       • 1 = no increased risk between populations
       • OR>1  increased risk OR<1  decreased risk
   – Models adjusted for multiple personal, building characteristic
     and environmental variables
   – Used GEE (General Estimating Equation) to adjust for across-
     building effects
   – Interpret statistical analyses with caution
       •   BASE study a cross-sectional design
       •   Does not prove causality
       •   Must show physical plausibility
       •   Must be reproduced
            Hypotheses I
• Indoor air contaminant exposures are
  responsible in-part for BRS
• Increases in per-person ventilation rates
  reduce prevalence of BRS
Factors Governing Indoor Pollutant
    Concentrations and Health
                                         Chemistry
Source         Sources
                              Transformation
Control       Transport &
                     Health Effects
               Dispersion

                                   Pollutant
                   Removal       Concentrations


Ventilation                         Exposure


                                      Effects
                     CO2 Metric
   [dCO2] = Indoor [CO2] – Outdoor [CO2]
   Steady-State dCO2 ~ per-person ventilation
   rate BASE Data           dCO (ppm)        2
               Mean                         250
               Maximum                      610
               Number of Buildings:               100

Office Building Ventilation
•ASHRAE Standard 62-1999* … 10 Ls-1 person-1
•Approximate steady state indoor [CO2] of 870 ppm
 assuming outdoor [CO2] ~ 350 ppm (i.e., dCO2 ~ 520 ppm)
*appropriate   value for 1990s BASE Study
           MLR Results: Dose-Response
                                                      1   10
•   Adjusteda analyses of trend                                MM

    used to identify dose-                                     Dry Eyes
    response relationships
    between dCO2 and                                           Sore Thrt.

    symptoms                                                   Stuffy
     • Four elevated CO2                                       Nose/Sinus

       concentration ranges vs.
                                                               LResp
       control
• Statistically significant (p<                                Short Brth.


  0.05) dose-response                                          Tight
                                                               Chest
  relationships with
  increasing dCO2                                              Cough


                                                               Wheeze
    aAdjustedfor age, gender, presence of carpet in
    workspace, smoking status, thermal exposure,
    RH, and 1,2,4-TMB and SENSITIVEe.
        Principal Components Analysis (PCA)
                                 Office Machines                    Source-based
Outdoor Air                                                        exposure metrics
                           VOC
                           concentrations                         PC1 (photocopiers)
                               in
          o-xylene
                                                                  PC2 (motor vehicles)
      m & p-xylenes
       ethylbenzene
                             buildings                    PCA
          benzene
       ethyl acetate                           dodecane           PC3 (tobacco smoke)
           toluene                             n-decane
                                               deltaCO
       butyl acetate
           styrene
                       1,4-dichlorobenzene      octane            PC4 (paint)
                              a-pinene
  1,2,4-trimethylbenzene
                         tetrachloroethene
        naphthalene
                           formaldehyde
        d-limonene
                       1,1,1-trichloroethane


                                      Building Materials
Smoking                                                         A few independent
     Numerous, highly                                           principal components
     correlated VOCs                                            related to the VOC
                                                                sources
                            BRS Risk Factors
• Air Conditioners
   – 1.3<OR<3.0 (Seppänen and Fisk 2002)
• Mechanical Ventilation
   – Moderate evidence (Seppänen and Fisk 2002)
• Low Ventilation Rates
   – <10 L/s per person
   – 1.1<OR<6
   (Seppänen et al. 1999, Apte et al. 2000, Erdmann and Apte 2004)

• HVAC Filters
   – Headache
        • Old filter ~ Intensity of headache (Clausen et al. 2002)
   – Performance
        • Old filters associated with Performance
        • New filter and  vent. rate  Performance
        • Old filter and  vent. rate  Performance
        (Wargocki et al. 2004)
            Hypotheses II
• Hypothesis 1. Increasing levels of outdoor
  ozone leads to higher prevalence of BRS
  among occupants within a building.
• Hypothesis 2. Air filters are a sink for ozone
  and as contaminant sources that can increase
  occupant BRS. Some air filter materials in the
  presence of elevated ozone concentrations
  may increase occupants’ risk of BRS.
           BASE Study Ozone
Ozone and BASE
  – Outdoor ozone
    collected from EPA
    ambient sites
  – Only one BASE
    building 8-h ozone >
    NAAQS of 157 g m-3
    during the study time
    period
  – Late afternoon ozone
    mean: 67.6 g m-3 (~34
    ppb)
             Crudest Relationships
      Annual Arithmetic Mean (AM) Ozone
Prevalence Mucous Membrane       Prevalence Lower Respiratory




Prevalence Sore Throat           Prevalence Wheeze




 Arithmetic Mean [Ozone] (ppb)    Annual AM [Ozone] (ppb)
                                                                 Multivariate BRS Risk
                                                          per 10 g m-3 Late Work Day Ozone
                                                    1.1
                      per 10 g m-3 Ambient Ozone
Odds Ratio (95% CI)




                                                    1.0




                                                                OR per 10 g m-3 outdoor ozone
                                                    0.9

                                                           LR         gh   UR              es      CN            ki
                                                                                                                    n        he
                                                                    ou                   ey     FT             S          ac
                                                                C                   ry                    ry            ad
       Solid circles statistically significant at 95% confidence level
                                                                                D                       D          He
          VOC-Ozone Correlations
Unsaturated C=O
                      Compound                     r   n Saturated   C=O   Sampling method
compounds are         Formaldehyde              0.18+ 99    N         Y    DNPH
often products        Acetaldehyde              0.28* 85    N         Y    DNPH
                      Pentanal                 0.40* 40     N         Y    Multisorbent
oxidation             Hexanal                  0.38* 40     N         Y    Multisorbent
                      Nonanal                  0.60** 40    N         Y    Multisorbent
                      Ethanol                   0.49+ 13    Y         N    Canister
                      1-Butanol                 0.38* 40    Y         N    Multisorbent
                      2-Ethylhexanol             0.25 40    Y         N    Multisorbent
                      Phenol                     0.26 40    N         N    Multisorbent
                      2-Butoxyethanol           0.32* 40    Y         N    Multisorbent
                      Ethyl Acetate              0.12 69    N         Y    Multisorbent
                      Texanol 1&3               0.32* 40    N         Y    Multisorbent
BTEX compounds        TXIB                       0.19 40    N         Y    Multisorbent
track nitric oxide    n-Undecane                 0.11 86    Y         N    Canister
                      Benzene                  -0.29* 69    N         N    Multisorbent
that reacts with      o-Xylene                  -0.12 69    N         N    Multisorbent
ozone                 Ethylbenzene              -0.19 69    N         N    Multisorbent
                      Naphthalene                0.13 69    N         N    Multisorbent
                      d-Limonene                 0.11 99    N         N    Canister
                      Chloromethane             0.24* 86    Y         N    Canister
                     +: p < 0.10, *: p < 0.05, **: p< 0.0001
     Hypothesis 1: Discussion
• Interpret with caution - association does not prove
  causality
• BRS most strongly associated with late workday
  ambient ozone averages
• Reducing entrained ozone
   – to BASE lowest ozone level (4.9 μg m-3)
   – assuming causality
   – could reduce upper respiratory, dry eyes, neurological and
     headache BRS by 45%, 35%, 35% and 33%, respectively
• Known products of indoor ozone chemistry
   – Formaldehyde, acetaldehyde, pentanal, hexanal and
     nonanal
   – showed fairly large positive correlations with ozone
   – these compounds are known sensory irritants and some are
     known carcinogens
            Filters in BASE Buildings
  • Most common types of single filter materials
     – fiberglass
     – polyester
     – synthetic
  • Most common blends of filter materials
     – cotton-polyester
     – cotton-synthetic
  • Final Model
     – polyester/synthetic filter material vs. fiberglass filter -
       34 Buildings
                                                  Any
               Any                            Fiberglass,                      Only Poly/
    No                  No Poly/                                        Only Synthetic
           Fiberglass                           no P/S
Fiberglass              Synthetic Any Poly/              Any Poly/   Fiberglass Filter
              Filter                             Filter
                                                                                  ç

   Filter                 Filter Synthetic               Synthetic      Filter
              (41)                  Filter       (29)                            (16)
   (50)                   (44)                             Filter       (26)
                                    (47)                   (47)
             Model Adjustments
  Risk factors                  Other Covariates
CPSF Buil dings                 Female
Ozone > 67.6 mg/m3              At least one sensitivity
Filter covariates               Age ³ 40
MERV > 7                        Current smoker
Filter Shape: Flat or Pleated   dCO 2 (ppm/100)
Filter Fit: Good                Heati ng degree-days (C-days)/100
Filter Condition: Good          Cooli ng degree-days (C-days)/100
Panel filter replacement freq   ThermExp (C-hours > 20 C)
  Semi-quarterly or more        RH < 20%
  Qrtrly. or Semi-annually      Season: Winter
  Annually or less              1,2,4-TMB (ppb)
    Results: Full Model Adjusted for
              Confounding
            Occupants in Fiberglass            Occupants in Poly/Syn
       a.           Blds.                b.           Blds.
          BRS               OR              BRS       OR      95% CI
          LR               1.00             LR       1.45 0.56-3.77
          Cough            1.00             Cough    2.97 0.83-10.61
          UR               1.00             UR       1.15 0.53-2.49
Low O3    Dry Eyes         1.00             Dry Eyes 2.07 0.88-4.87
          FT/CN            1.00             FT/CN    1.93 1.01-3.71
          Dry Skin         1.00             Dry Skin 0.79 0.25-2.45
          Headache         1.00             Headache 1.16 0.65-2.06


        c. BRS        OR      95% CI     d. BRS        OR     95% CI
           LR         1.47   0.58-3.71      LR         5.90 1.73-20.08
           Cough      1.33   0.56-3.16      Cough      2.67 1.00-7.10
           UR         1.10   0.65-1.88      UR         2.63 1.36-5.08
High O3    Dry Eyes   1.37   0.79-2.36      Dry Eyes   2.26 1.17-4.38
           FT/CN      1.54   1.02-2.35      FT/CN      2.76 1.60-4.76
           Dry Skin   1.15   0.50-2.62      Dry Skin   0.37 0.14-1.02
           Headache   1.15   0.69-1.91      Headache   2.54 1.25-5.15
                          Joint Risk
             Ozone >67.6 g m-3 and Poly/Syn Filters
                                 UCL=20
                      8.0                                                                  a.
                                                                                                 Occupants in Fiberglass

                                                                                                BRS
                                                                                                         Blds.
                                                                                                                 OR
                                                                                                                              b.
                                                                                                                                     Occupants in Poly/Syn

                                                                                                                                   BRS
                                                                                                                                            Blds.
                                                                                                                                            OR      95% CI
                                                                                                LR              1.00               LR      1.45 0.56-3.77
                                                                                                Cough           1.00               Cough   2.97 0.83-10.61
                                                                                                UR              1.00               UR      1.15 0.53-2.49



                      7.0
                                                                                  Low O3        Dry Eyes        1.00               Dry Eyes2.07 0.88-4.87
                                                                                                FT/CN           1.00               FT/CN   1.93 1.01-3.71
                                                                                                Dry Skin        1.00               Dry Skin0.79 0.25-2.45
                                                                                                Headache        1.00               Headache1.16 0.65-2.06


                                                                                          c. BRS           OR      95% CI     d. BRS          OR     95% CI
Odds Ratio (95% CI)




                                                                                             LR            1.47   0.58-3.71      LR           5.90 1.73-20.08




                      6.0
                                                                                             Cough         1.33   0.56-3.16      Cough        2.67 1.00-7.10
                                                                                             UR            1.10   0.65-1.88      UR           2.63 1.36-5.08
                                                                                  High O3    Dry Eyes      1.37   0.79-2.36      Dry Eyes     2.26 1.17-4.38
                                                                                             FT/CN         1.54   1.02-2.35      FT/CN        2.76 1.60-4.76
                                                                                             Dry Skin      1.15   0.50-2.62      Dry Skin     0.37 0.14-1.02
                                                                                             Headache      1.15   0.69-1.91      Headache     2.54 1.25-5.15




                      5.0

                      4.0

                      3.0

                      2.0

                      1.0

                      0.0

                            LR       gh    UR            es        /C
                                                                      N            ki
                                                                                      n                                he
                                   ou                  Ey        T               S                                  ac
                                  C               ry           F            ry                                    ad
                                                D
        Solid circles statistically significant at 95% confidence level
                                                                          D                       He
                      Risk from Ozone >67.6 g m-3 in Poly/Syn
                                   Filter Buildings
                                 UCL=13.4
                      8.0
                                                                                               Occupants in Fiberglass             Occupants in Poly/Syn
                                                                                         a.            Blds.                b.            Blds.
                                                                                              BRS              OR                BRS      OR      95% CI



                      7.0
                                                                                              LR              1.00               LR      1.45 0.56-3.77
                                                                                              Cough           1.00               Cough   2.97 0.83-10.61
                                                                                              UR              1.00               UR      1.15 0.53-2.49
                                                                                Low O3        Dry Eyes        1.00               Dry Eyes2.07 0.88-4.87
                                                                                              FT/CN           1.00               FT/CN   1.93 1.01-3.71
                                                                                              Dry Skin        1.00               Dry Skin0.79 0.25-2.45
                                                                                              Headache        1.00               Headache1.16 0.65-2.06
Odds Ratio (95% CI)




                      6.0
                                                                                        c. BRS           OR      95% CI     d. BRS          OR     95% CI
                                                                                           LR            1.47   0.58-3.71      LR           5.90 1.73-20.08
                                                                                           Cough         1.33   0.56-3.16      Cough        2.67 1.00-7.10
                                                                                           UR            1.10   0.65-1.88      UR           2.63 1.36-5.08
                                                                                High O3    Dry Eyes      1.37   0.79-2.36      Dry Eyes     2.26 1.17-4.38
                                                                                           FT/CN         1.54   1.02-2.35      FT/CN        2.76 1.60-4.76
                                                                                           Dry Skin      1.15   0.50-2.62      Dry Skin     0.37 0.14-1.02
                                                                                           Headache      1.15   0.69-1.91      Headache     2.54 1.25-5.15




                      5.0

                      4.0

                      3.0

                      2.0

                      1.0

                      0.0

                            LR         gh   UR            es       CN             ki
                                                                                     n                                  he
                                    ou                  Ey       T/             S                                    ac
                                  C                ry          F           ry                                      ad
                                                 D                       D                          He
       Solid circles statistically significant at 95% confidence level
                        Risk from Poly/Syn relative to Fiberglass
                               Filters: Ozone >67.6 g m-3
                                 UCL=8.3
                      8.0
                                                                                                             Occupants in Fiberglass             Occupants in Poly/Syn
                                                                                                       a.            Blds.                b.            Blds.
                                                                                                            BRS              OR                BRS      OR      95% CI



                      7.0
                                                                                                            LR              1.00               LR      1.45 0.56-3.77
                                                                                                            Cough           1.00               Cough   2.97 0.83-10.61
                                                                                                            UR              1.00               UR      1.15 0.53-2.49
                                                                                              Low O3        Dry Eyes        1.00               Dry Eyes2.07 0.88-4.87
                                                                                                            FT/CN           1.00               FT/CN   1.93 1.01-3.71
                                                                                                            Dry Skin        1.00               Dry Skin0.79 0.25-2.45
                                                                                                            Headache        1.00               Headache1.16 0.65-2.06
Odds Ratio (95% CI)




                      6.0
                                                                                                      c. BRS           OR      95% CI     d. BRS          OR     95% CI
                                                                                                         LR            1.47   0.58-3.71      LR           5.90 1.73-20.08
                                                                                                         Cough         1.33   0.56-3.16      Cough        2.67 1.00-7.10
                                                                                                         UR            1.10   0.65-1.88      UR           2.63 1.36-5.08
                                                                                              High O3    Dry Eyes      1.37   0.79-2.36      Dry Eyes     2.26 1.17-4.38
                                                                                                         FT/CN         1.54   1.02-2.35      FT/CN        2.76 1.60-4.76
                                                                                                         Dry Skin      1.15   0.50-2.62      Dry Skin     0.37 0.14-1.02
                                                                                                         Headache      1.15   0.69-1.91      Headache     2.54 1.25-5.15



                      5.0

                      4.0

                      3.0

                      2.0

                      1.0

                      0.0

                            LR       gh                UR              es         CN              ki
                                                                                                     n                                    he
                                   ou                                Ey         T/              S                                      ac
                                  C                            ry           F            ry                                          ad
                                                             D                         D                               He
       Solid circles statistically significant at 95% confidence level
        Hypothesis 2: Discussion
• BRS - Polyester/synthetic filter materials highly,
  significantly associated >> with higher ozone
   – physico-chemical mechanisms unknown
• Results are statistical associations
• Replication needed in addition studies
• Suggests that ozone mitigation and proper filter
  selection
   – Reduce BRS 30% to 60% in buildings
• Possible mitigation strategies
   – Reduce ambient ozone -> Clean Air Act
   – Outside air cleaning for HVAC systems
   – Appropriate HVAC filter selection -> research needed
    Discussion: Outside Air Cleaning
• ASHRAE 62.1-2007 requires ozone air filtration
    -   [O3] exceeds 160 ppb
• Current public review of new trigger level related to recent
  lowering of ozone criteria level
    - 80 ppb
• Expands number of US counties from <100 to >300
• Activated carbon air filtration shown effective
• Activated carbon lifetime long for O3 removal
• Low ∆P carbon impregnated air filters available
• Research needed to characterize lifetime and
  effectiveness of low ∆P filters
• Important role of industry in this process
• Potential increase in market for activated carbon
  impregnated filters
                  Conclusions
BRS is ventilation (dCO2) dependent
Ambient ozone is associated with increased BRS
Ozone-initiated chemistry a likely cause of symptoms
Ozone interactions with HVAC system materials is a
likely factor in causation of BRS
More research needed to confirm causation
                    Further Research

   Filter Studies                     Field Studies
   Surface chemistry                  Intervention studies
   Materials physics and              Cross-sectional studies
   chemistry
            Challenge Question

What will air filtration look like in 20 years?
DOE: Net Zero energy buildings
Cost of energy
Climate change
Poorer outdoor air quality
More awareness of indoor air quality and health/productivity
effects

								
To top