the dependence of indoor pah concentrations on outdoor pahs and traffic volume in an urban...

IntroductionMethodsResults

Conclusions

The Dependence of Indoor PAH

Concentrations on Outdoor PAHs and

Traffic Volume in an Urban Residential

Environment

B. Rey de Castro, Sc.D.

WestatRockville, Maryland USA

March 25, 2010

[email protected] Indoor PAHs @ Gradient


Conclusions

Outline

1 Introduction

2 MethodsMonitoring SiteMeasurementsImputation of Missing Values

3 ResultsExploratory AnalysisTime Series Models

4 Conclusions



Conclusions

PAH Health Risks

PAHs among Mobile Source Air Toxics

Potential population at risk: 17.8 million residences

Toxicity: Cancer

18th Century scrotal cancer among chimney sweepsLung cancer from occupational exposures

Toxicity: Neurodevelopment

Low birthweightRespiratory deficitsChromosomal degradationDiminished cognition



Conclusions

Monitoring SiteMeasurementsImputation of Missing Values

Outline

1 Introduction



4 Conclusions



Conclusions


Monitoring Site



Conclusions


Baltimore Traffic Study Objectives

Sustained, continuous monitoring: 12 months

High temporal resolution: 10-minute intervals

Simultaneous monitoring of traffic & covarying factors

Control expected autocorrelation: time series analysis

Conclude long-term characteristics of PAH exposure



Conclusions


Measurements

PAHs

EcoChem PAS 2000Selective ionization of particle-bound PAHsAlternating indoor-outdoor 5-minute samplingCombined into 10-minute observations

Traffic

Pneumatic counter5-minute counts

Weather

Rooftop weather station (30-minute)NWS airport measurements (60-minute)

All data transformed to 10-minute observational interval



Conclusions


Imputation of Missing Values

Linear regression with reference data

Predictions substituted for missing values

Add pseudorandom variate to reduce bias

Yimpute = Ypredict + N(0, σ2)

N = 52,560

July 1, 2002 to June 30, 2003



Conclusions

Exploratory AnalysisTime Series Models

Outline

1 Introduction



4 Conclusions



Conclusions


Variability over Time



Conclusions


Workday vs. Non-Workday



Conclusions


Temperature & Dew Point



Conclusions


Mixing Height & Wind Speed



Conclusions


Models With Autocorrelation

Indoor PAHTraffic, outdoor PAHs, wind speed, wind direction,temperature, dew point, season, workdayARMA[3,3] autocorrelation

Yt,in = µin+

p∑i=1

βiXi ,t+MA(1 : 3)

AR(1 : 3)× AR(144)× AR(1008)+εt,in

Outdoor PAHTraffic, wind speed, wind direction, temperature, dewpoint, season, workdayARMA[1,1] autocorrelation

Yt,out = µout+

p∑i=1

βiXi ,t+MA(1)

AR(1)× AR(144)× AR(1008)+εt,out



Conclusions


Indoor Parameters: Treemap Visualization



Conclusions


Outdoor Parameters: Treemap Visualization



Conclusions


Wind Direction: Outdoor vs. Indoor

Indoor PAHs, SW–S–SE: 0.59 – 1.16 ng/m3Outdoor PAHs, WSW–S–NE: 0.95 – 9.78 ng/m3



Conclusions

Outline

1 Introduction



4 Conclusions



Conclusions

Conclusions

1 Indoor PAHs depend on both traffic volume & outdoorPAHs

2 Outdoor PAHs depend on traffic volume

3 Observed diminished effect of traffic volume in afternoon

4 Season (Spring & Summer 2003) was strongest predictorof indoor & outdoor PAHs

5 Contributions from wind direction differ between indoor &outdoor PAHs

6 Meteorology & workday had significant effects

7 Autocorrelation was significant



Conclusions

Acknowledgements

Patrick N. Breysse Timothy J. BuckleyJana N. Mihalic Alison S. Geyh

Lu Wang

EPA grant

On SlideShare: http://cli.gs/BTSpahIndoorGradient

B. Rey de Castro, Sc.D.410-929-3583



Conclusions

Summary: Quantitative

Indoor PAHs

0.57 ng/m3 per 100 vehicles every 10 minutes0.16 ng/m3 per ng/m3 outdoor PAHCombination of fresh and aged PAHs

Outdoor PAHs

3.17 ng/m3 per 100 vehicles every 10 minutes

Season (Spring & Summer 2003) was strongest predictor

Indoor PAHs: 9.27 – 9.99 ng/m3Outdoor PAHs: 9.26 – 9.78 ng/m3

Workday

Indoor PAHs: 1.64 ng/m3Outdoor PAHs: 3.01 ng/m3



Conclusions

Summary: Quantitative

MeteorologyIndoor PAHs

Wind speed: -0.38 ng/m3 per m/sTemperature: -2.48 ng/m3 per 5 CDew point: 1.87 ng/m3 per 5 C

Outdoor PAHs

Wind speed: -0.79 ng/m3 per m/sTemperature: -3.45 ng/m3 per 5 CDew point: 2.77 ng/m3 per 5 C


the dependence of indoor pah concentrations on outdoor pahs and traffic volume in an urban...

Technology

bound pahs

indoorindoor pahs

ngm3outdoor pahs

autocorrelationindoor

continuous monitoring

minute sampling

minute observational

trac volume