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

Clifford P. WeiselClifford P. WeiselEnvironmental and Occupational Health Environmental and Occupational Health

Sciences Institute, Piscataway, NJSciences Institute, Piscataway, NJ

With: J Zhang, BJ Turpin, MT Morandi, S With: J Zhang, BJ Turpin, MT Morandi, S Colome, Thomas H. Stock, & DM SpektorColome, Thomas H. Stock, & DM Spektor

Presented at:Presented at:

The 2004 MIT Endicott Air Toxics The 2004 MIT Endicott Air Toxics SymposiumSymposium

EXPOSURE CONSIDERATIONSEXPOSURE CONSIDERATIONS People spend more time indoors (home, People spend more time indoors (home,

work, school, recreation, etc.) than work, school, recreation, etc.) than outdoor, but also in transitoutdoor, but also in transit– Percent time can vary by location & seasonPercent time can vary by location & season

Air toxics Air toxics – have outdoor sources which can enter have outdoor sources which can enter

(though often modified) indoors(though often modified) indoors– can be produced from activities or generated can be produced from activities or generated

indoorsindoors– can be elevated in “special” micro- can be elevated in “special” micro-

environments (i.e. automobile cabins)environments (i.e. automobile cabins)

RIOPA STUDY HYPOTHESESRIOPA STUDY HYPOTHESES

1) At residences immediately adjacent to 1) At residences immediately adjacent to outdoor sources a measurable and outdoor sources a measurable and significant portion of the air toxic significant portion of the air toxic exposures will be attributable to ambient exposures will be attributable to ambient sourcessources

2) Residential air exchange rates and 2) Residential air exchange rates and ambient air measurements can predict ambient air measurements can predict the contribution from ambient sources to the contribution from ambient sources to indoor air & personal exposureindoor air & personal exposure

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

ATTRIBUTING AIR TOXIC ATTRIBUTING AIR TOXIC SOURCES – OUTDOOR/INDOORSOURCES – OUTDOOR/INDOOR

Examine scatter plots of personnel air, Examine scatter plots of personnel air, indoor air and outdoor air concentrations indoor air and outdoor air concentrations for each sampling setfor each sampling set

Model the indoor concentrations based Model the indoor concentrations based on outdoor concentrations, penetration on outdoor concentrations, penetration factors and air exchange ratesfactors and air exchange rates

Use statistical analyses to predict Use statistical analyses to predict personal concentration based on activity personal concentration based on activity data (future analyses)data (future analyses)

OUTDOOR SOURCE DOMINATEDOUTDOOR SOURCE DOMINATED

Methyl tert butyl ether(n=505)

0

10

20

30

40

50

0 10 20 30 40 50

Outdoor concentration (mg/m 3)

Ind

oo

r co

nce

ntr

atio

n (

mg

/m3)

1:1 line

Methyl tert butyl ether(n=504)

0

10

20

30

40

50

0 10 20 30 40 50

Outdoor concentration (mg/m 3)

Per

son

al c

on

cen

trat

ion

(m

g/m

3) 1:1 line

Methyl tert butyl ether(n=502)

0

10

20

30

40

50

0 10 20 30 40 50

Indoor concentration (mg/m 3)

Per

son

al c

on

cen

trat

ion

(m

g/m

3) 1:1 line

Scatter around 1:1 line for all three plots are fairly random – outdoor source dominate with little loss from outdoor

OUTDOOR SOURCE DOMINATEDOUTDOOR SOURCE DOMINATEDCompounds that fit this categoryCompounds that fit this category

Methyl Methyl terttert butyl ether (MTBE) butyl ether (MTBE)Methylene chlorideMethylene chloride

Carbon tetrachlorideCarbon tetrachlorideTrichloroethyleneTrichloroethylenePropionaldehydePropionaldehydeCrotonaldehydeCrotonaldehyde

These are not compound present in many These are not compound present in many consumer productsconsumer products

INDOOR SOURCE DOMINATEDINDOOR SOURCE DOMINATED

Formaldehyde(n=444)

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70

Outdoor concentration (µg/m 3)

Ind

oo

r co

ncen

trati

on

(µg

/m3)

1:1 line

Formaldehyde(n=599)

0

20

40

60

80

100

120

140

160

0 20 40 60 80 100 120 140 160

Outdoor concentration (µg/m 3)

Pers

on

al co

ncen

trati

on

(µg

/m3)

1:1 line

Formaldehyde(n=599)

0

20

40

60

80

100

120

140

160

0 20 40 60 80 100 120 140 160

Indoor concentration (µg/m 3)

Pers

on

al co

ncen

trati

on

(µg

/m3)

1:1 line

Elevated levels for both the indoor and personal concentration compared to the outdoor levels, while the personal and indoor scatter around the 1:1 line - indoor sources dominate

INDOOR SOURCE DOMINATEDINDOOR SOURCE DOMINATEDCompounds that fit this categoryCompounds that fit this category

Major Indoor ComponentMajor Indoor Component

ChloroformChloroform

αα-Pinene-Pinene

ββ-Pinene-Pinene

d-Limonened-Limonene

1,4-Dichlorobenzene1,4-Dichlorobenzene

FormaldehydeFormaldehyde

AcetaldehydeAcetaldehyde

Borders on 1:1 LineBorders on 1:1 Line

StyreneStyrene

AcetoneAcetone

BenzaldehydeBenzaldehyde

Some home show very strong indoor sources

MIXED SOURCESMIXED SOURCESm,p -Xylene

(n=505)

0

50

100

150

200

250

0 50 100 150 200 250

Outdoor concentration (mg/m 3)

Ind

oo

r co

nce

ntr

atio

n (

mg

/m3)

1:1 line

m,p -Xylene(n=504)

0

50

100

150

200

250

0 50 100 150 200 250

Outdoor concentration (mg/m 3)

Per

son

al c

on

cen

trat

ion

(m

g/m

3) 1:1 line

m,p -Xylene(n=502)

0

50

100

150

200

250

0 50 100 150 200 250

Indoor concentration (mg/m 3)

Per

son

al c

on

cen

trat

ion

(m

g/m

3) 1:1 line

m,p -Xylene(n=505)

0

10

20

30

40

50

0 10 20 30 40 50

Outdoor concentration (mg/m 3)

Ind

oo

r co

nce

ntr

atio

n (

mg

/m3) 1:1 line

m,p -Xylene(n=504)

0

10

20

30

40

50

0 10 20 30 40 50

Outdoor concentration (mg/m 3)

Per

son

al c

on

cen

trat

ion

(m

g/m

3) 1:1 line

m,p -Xylene(n=502)

0

10

20

30

40

50

0 10 20 30 40 50

Indoor concentration (mg/m 3)

Per

son

al c

on

cen

trat

ion

(m

g/m

3) 1:1 line

Elevated levels for both the indoor and personal concentration compared to the outdoor levels for some samples – indoor sources dominateother samples scatter around the 1:1 line – outdoor sources dominate

MIXED SOURCESMIXED SOURCESCompounds that fit this categoryCompounds that fit this category

BenzeneBenzene

TolueneToluene

TetrachloroethyleneTetrachloroethylene

m,pm,p Xylene Xylene

oo Xylene Xylene

Ethyl benzeneEthyl benzene

LOSSES DURING TRANSPORTLOSSES DURING TRANSPORT

PM 2.5

(n=292)

0

20

40

60

80

100

120

0 20 40 60 80 100 120

Outdoor concentration (µg/m 3)

Ind

oo

r co

ncen

trati

on

(µg

/m3)

1:1 line

PM 2.5

(n=256)

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100 120 140 160 180

Outdoor concentration (µg/m 3)

Pers

on

al co

ncen

trati

on

(µg

/m3)

1:1 line

PM 2.5

(n=246)

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100 120 140 160 180

Indoor concentration (µg/m 3)

Pers

on

al co

ncen

trati

on

(µg

/m3)

1:1 line

Lower indoor values indicative of losses during penetrationIndividual higher indoor values -- indoor sources dominatePersonal higher than indoor or outdoor -- indicative of an activity source.

LOSSES DURING TRANSPORTLOSSES DURING TRANSPORTCompounds that fit this categoryCompounds that fit this category

PMPM2.52.5

AcroleinAcrolein

SUMMARY OF SCATTER PLOTSSUMMARY OF SCATTER PLOTS Compounds can be classified into four groups Compounds can be classified into four groups

dependant on indoor-outdoor concentrationdependant on indoor-outdoor concentration– Majority of homes dominated by outdoor airMajority of homes dominated by outdoor air– Majority of homes dominated by indoor Majority of homes dominated by indoor

sourcessources– Significant portion of homes dominated by Significant portion of homes dominated by

outdoor air with others showing indoor outdoor air with others showing indoor sourcessources

– Losses of compounds when penetration Losses of compounds when penetration indoors occurs with indoor/personal indoors occurs with indoor/personal sources evidentsources evident

MODELING OUTDOOR MODELING OUTDOOR CONTRIBUTIONS TO INDOORSCONTRIBUTIONS TO INDOORS

Goal to evaluate the role of outdoor intrusion Goal to evaluate the role of outdoor intrusion on the indoor air concentrationon the indoor air concentration– Use indoor & outdoor levels and AERUse indoor & outdoor levels and AER– Account for penetration factors and loss termsAccount for penetration factors and loss terms

Mass balance modelMass balance model Random Component super-position Random Component super-position

statistical modelstatistical model

OUTDOOR CONTRIBUTIONS TO INDOOR AIR OUTDOOR CONTRIBUTIONS TO INDOOR AIR TOXIC CONCENTRATIONS USING A MASS TOXIC CONCENTRATIONS USING A MASS

BALANCE MODEL - FOR PMBALANCE MODEL - FOR PM

Category k 1/hr(95% CI)

S/V g/m3hr(95% CI)

% OutdoorContribution

PM2.5 (N)

Overall study(262) 1.04 (0.48, 1.59) 17.9 (7.6, 28.1) 53

California (100) 0.95 (0.53, 1.37) 13.5 (5.0, 19.9) 62

New Jersey (84) 1.07 (-0.34, 2.48) 22.9 (-7.6, 53.4) 50

Texas (78) 1.06 (-1.49, 3.61) 18.3 (-24.3, 61.0) 341.06 (-1.49, 3.61) 18.3 (-24.3, 61.0)

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 %

OUTDOOR CONTRIBUTIONS TO INDOOR AIR OUTDOOR CONTRIBUTIONS TO INDOOR AIR TOXIC CONCENTRATIONS USING A MASS TOXIC CONCENTRATIONS USING A MASS

BALANCE MODEL -FOR CARBONYLSBALANCE MODEL -FOR CARBONYLS

Category k 1/hr(95% CI)

S/V g/m3hr(95% CI)

% OutdoorContribution

Carbonyls (N)Formaldehyde (416) 14.8 (2.61, 27.1) 333 (70.3, 595) 1.3

Acetaldehyde (416) 0.65 (0.22, 1.08) 24.8 (13.9, 35.7) 17

Acetone (416) 0.065 (-.038, .17) 3.85 (1.88, 5.81) 56

Glyoxal (416) 0.75 (0.45, 1.04) 2.24 (1.51, 2.97) 32

Methylglyoxal (413) 0.10 (.068, 0.13) 0.59 (0.41, 0.77) 59

OUTDOOR CONTRIBUTIONS TO INDOOR AIR OUTDOOR CONTRIBUTIONS TO INDOOR AIR TOXIC CONCENTRATIONS USING A MASS TOXIC CONCENTRATIONS USING A MASS

BALANCE MODEL -FOR VOCSBALANCE MODEL -FOR VOCS

Category k 1/hr(95% CI)

S/V g/m3hr(95% CI)

% OutdoorContribution

VOCs (N)Methyl tert ButylEther (456)

0.180 (.045, .315) 4.34 (2.22, 6.45) 73

Benzene (456) 0.332 (.028, .635) 2.11 (.787, 3.43) 52

Toluene (456) 0.282 (.036, .528) 9.60 (4.88, 14.3) 34

Ethyl Benzene (457) 0.836 (-.412, 2.08) 3.08 (-.447, 6.61) 26

m,p Xylene (457) 0.589 (-.402, 1.58) 6.86 (-1.4, 15.1) 33

o Xylene (457) 76.37 (-229, 382) 188 (-562, 938) 36

1,4 Dichlorobenzene(457)

0.628 (-.777, 2.03) 84.9 (-30.7, 200) 12(457)

0.628 (-.777, 2.03) 84.9 (-30.7, 200) 12

SUMMARY OF MODELSSUMMARY OF MODELS PM showed loss during penetration PM showed loss during penetration

indoor with improvement in the estimate indoor with improvement in the estimate as individual home variability was as individual home variability was accounted foraccounted for

Carbonyls showed loss (water solubility Carbonyls showed loss (water solubility effects?) on some strong indoor sourceseffects?) on some strong indoor sources

Non-polar VOCs no losses during Non-polar VOCs no losses during penetration with ambient influence penetration with ambient influence consistent with scatter plot suggestionsconsistent with scatter plot suggestions

AFFECT OF PROXIMITY ON AFFECT OF PROXIMITY ON AMBIENT AIR CONCENTRATIONAMBIENT AIR CONCENTRATION

Mobile SourcesMobile Sources

Assign locations to all homes and source location Assign locations to all homes and source location using GIS techniquesusing GIS techniques

Calculate distances between home and closest Calculate distances between home and closest point to roadway and each point or area sourcepoint to roadway and each point or area source

Conduct statistical evaluation – linear regression Conduct statistical evaluation – linear regression analyses – after appropriate transformations. analyses – after appropriate transformations. – Distance and meteorology as independent variables.Distance and meteorology as independent variables.– Evaluate statistical appropriateness of associations and Evaluate statistical appropriateness of associations and

outliersoutliers

SUMMARY OF PROXIMITY SUMMARY OF PROXIMITY ANALYSESANALYSES

Mobile source compounds were inversely related Mobile source compounds were inversely related to distance to major highways & gas stations, wind to distance to major highways & gas stations, wind speed (some) – positive to atmospheric stabilityspeed (some) – positive to atmospheric stability– MTBE stronger to Gas StationsMTBE stronger to Gas Stations– Toluene had point source influenceToluene had point source influence– Carbonyls not related to distance only Carbonyls not related to distance only

meteorologymeteorology Tetrachloroethylene was inversely related to Tetrachloroethylene was inversely related to

distance to drycleaners, temperature, wind speed distance to drycleaners, temperature, wind speed - positive to atmospheric stability- positive to atmospheric stability

CONCLUSIONCONCLUSION

Ambient levels do not predict exposure to all Ambient levels do not predict exposure to all compoundscompounds

Indoor air can be modeled from outdoor Indoor air can be modeled from outdoor levels and AER to quantitatively evaluated levels and AER to quantitatively evaluated for outdoor air influencefor outdoor air influence

Proximity to sources can be statistically Proximity to sources can be statistically identified as affecting the ambient air around identified as affecting the ambient air around houses for a number of compoundshouses for a number of compounds

ACKNOWLEDGEMENTSACKNOWLEDGEMENTSFunding by Funding by (presentation not reviewed by agencies)(presentation not reviewed by agencies) Mickey Leland National Urban Air Toxics CenterMickey Leland National Urban Air Toxics Center Health Effects InstituteHealth Effects Institute NIEHS Center of Excellence ProgramNIEHS Center of Excellence Program US EPAUS EPA

Participants who allowed for life disruptionParticipants who allowed for life disruption

Sampling and Analyses TeamSampling and Analyses Team Leo Korn, Arthur Winer, Shahnaz Alimokhtari, Jaymin Kwon, Leo Korn, Arthur Winer, Shahnaz Alimokhtari, Jaymin Kwon,

Krishnan Mohan, Robert Harrington, Robert Giovanetti, William Krishnan Mohan, Robert Harrington, Robert Giovanetti, William Cui, Masoud Afshar, Silvia Maberti, Derek Shendell, Qing Yu Cui, Masoud Afshar, Silvia Maberti, Derek Shendell, Qing Yu Meng, Adam Reff, Andrea Polrdori, Robert Porcja, Yelena Meng, Adam Reff, Andrea Polrdori, Robert Porcja, Yelena Naumova, Jong Hoon Lee, Lin Zhang, Tina Fan, Jennifer Jones, L Naumova, Jong Hoon Lee, Lin Zhang, Tina Fan, Jennifer Jones, L Farrar, Yangrid Blossiers, and Marian FahreyFarrar, Yangrid Blossiers, and Marian Fahrey