Relationships of Indoor, Outdoor and Personal Air RIOPA Study

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Relationships of Indoor, Outdoor and Personal Air
(RIOPA) Study

• Clifford P. Weisel
• Environmental and Occupational Health Sciences
  Institute, Piscataway, NJ
• With J Zhang, BJ Turpin, MT Morandi, S Colome,
  Thomas H. Stock, DM Spektor
• Presented at
• The 2004 MIT Endicott Air Toxics Symposium

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EXPOSURE CONSIDERATIONS

• People spend more time indoors (home, work,
  school, recreation, etc.) than outdoor, but also
  in transit
• Percent time can vary by location season
• Air toxics
• have outdoor sources which can enter (though
  often modified) indoors
• can be produced from activities or generated
  indoors
• can be elevated in special micro- environments
  (i.e. automobile cabins)

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RIOPA STUDY HYPOTHESES

• 1) At residences immediately adjacent to outdoor
  sources a measurable and significant portion of
  the air toxic exposures will be attributable to
  ambient sources
• 2) Residential air exchange rates and ambient
  air measurements can predict the contribution
  from ambient sources to indoor air personal
  exposure

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STUDY DESIGN

• Sample 100 homes twice, 3 months apart in each of
  three urban centers
• Elizabeth, NJ Houston, TX Los Angeles, CA
• Target air toxics VOCs, Aldehydes, PM2.5 for
  mass, metals PAHs
• Personal, indoor outdoor air samples collected
  over 48 hours
• Personal samples from Adults who stay
  primarily at home children
• Air exchange measurements

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ATTRIBUTING AIR TOXIC SOURCES OUTDOOR/INDOOR

• Examine scatter plots of personnel air, indoor
  air and outdoor air concentrations for each
  sampling set
• Model the indoor concentrations based on outdoor
  concentrations, penetration factors and air
  exchange rates
• Use statistical analyses to predict personal
  concentration based on activity data (future
  analyses)

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OUTDOOR SOURCE DOMINATED
Scatter around 11 line for all three plots are
fairly random outdoor source dominate with
little loss from outdoor
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OUTDOOR SOURCE DOMINATEDCompounds that fit this
category

• Methyl tert butyl ether (MTBE)
• Methylene chloride
• Carbon tetrachloride
• Trichloroethylene
• Propionaldehyde
• Crotonaldehyde
• These are not compound present in many consumer
  products

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INDOOR SOURCE DOMINATED
Elevated levels for both the indoor and personal
concentration compared to the outdoor levels,
while the personal and indoor scatter around the
11 line - indoor sources dominate
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INDOOR SOURCE DOMINATEDCompounds that fit this
category

• Major Indoor Component
• Chloroform
• a-Pinene
• ß-Pinene
• d-Limonene
• 1,4-Dichlorobenzene
• Formaldehyde
• Acetaldehyde

• Borders on 11 Line
• Styrene
• Acetone
• Benzaldehyde

Some home show very strong indoor sources
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MIXED SOURCES
Elevated levels for both the indoor and personal
concentration compared to the outdoor levels for
some samples indoor sources dominate other
samples scatter around the 11 line outdoor
sources dominate
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MIXED SOURCESCompounds that fit this category

• Benzene
• Toluene
• Tetrachloroethylene
• m,p Xylene
• o Xylene
• Ethyl benzene

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LOSSES DURING TRANSPORT
Lower indoor values indicative of losses during
penetration Individual higher indoor values --
indoor sources dominate Personal higher than
indoor or outdoor -- indicative of an activity
source.
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LOSSES DURING TRANSPORTCompounds that fit this
category

• PM2.5
• Acrolein

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SUMMARY OF SCATTER PLOTS

• Compounds can be classified into four groups
  dependant on indoor-outdoor concentration
• Majority of homes dominated by outdoor air
• Majority of homes dominated by indoor sources
• Significant portion of homes dominated by outdoor
  air with others showing indoor sources
• Losses of compounds when penetration indoors
  occurs with indoor/personal sources evident

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MODELING OUTDOOR CONTRIBUTIONS TO INDOORS

• Goal to evaluate the role of outdoor intrusion on
  the indoor air concentration
• Use indoor outdoor levels and AER
• Account for penetration factors and loss terms
• Mass balance model
• Random Component super-position statistical model

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OUTDOOR CONTRIBUTIONS TO INDOOR AIR TOXIC
CONCENTRATIONS USING A MASS BALANCE MODEL - FOR PM
Loss rate (k) in hr-1 indoor source strength
(S/V) in µg m-3 hr-1, median outdoor
contributions to indoor air toxic concentrations
in
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OUTDOOR CONTRIBUTIONS TO INDOOR AIR TOXIC
CONCENTRATIONS USING A MASS BALANCE MODEL -FOR
CARBONYLS
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OUTDOOR CONTRIBUTIONS TO INDOOR AIR TOXIC
CONCENTRATIONS USING A MASS BALANCE MODEL -FOR
VOCS
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SUMMARY OF MODELS

• PM showed loss during penetration indoor with
  improvement in the estimate as individual home
  variability was accounted for
• Carbonyls showed loss (water solubility effects?)
  on some strong indoor sources
• Non-polar VOCs no losses during penetration with
  ambient influence consistent with scatter plot
  suggestions

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AFFECT OF PROXIMITY ON AMBIENT AIR
CONCENTRATIONMobile Sources

• Assign locations to all homes and source location
  using GIS techniques
• Calculate distances between home and closest
  point to roadway and each point or area source
• Conduct statistical evaluation linear
  regression analyses after appropriate
  transformations.
• Distance and meteorology as independent
  variables.
• Evaluate statistical appropriateness of
  associations and outliers

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SUMMARY OF PROXIMITY ANALYSES

• Mobile source compounds were inversely related to
  distance to major highways gas stations, wind
  speed (some) positive to atmospheric stability
• MTBE stronger to Gas Stations
• Toluene had point source influence
• Carbonyls not related to distance only
  meteorology
• Tetrachloroethylene was inversely related to
  distance to drycleaners, temperature, wind speed
  - positive to atmospheric stability

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CONCLUSION

• Ambient levels do not predict exposure to all
  compounds
• Indoor air can be modeled from outdoor levels and
  AER to quantitatively evaluated for outdoor air
  influence
• Proximity to sources can be statistically
  identified as affecting the ambient air around
  houses for a number of compounds

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ACKNOWLEDGEMENTS

• Funding by (presentation not reviewed by
  agencies)
• Mickey Leland National Urban Air Toxics Center
• Health Effects Institute
• NIEHS Center of Excellence Program
• US EPA
• Participants who allowed for life disruption
• Sampling and Analyses Team
• Leo Korn, Arthur Winer, Shahnaz Alimokhtari,
  Jaymin Kwon, Krishnan Mohan, Robert Harrington,
  Robert Giovanetti, William Cui, Masoud Afshar,
  Silvia Maberti, Derek Shendell, Qing Yu Meng,
  Adam Reff, Andrea Polrdori, Robert Porcja, Yelena
  Naumova, Jong Hoon Lee, Lin Zhang, Tina Fan,
  Jennifer Jones, L Farrar, Yangrid Blossiers, and
  Marian Fahrey