Grantee Research Project Results

Characterization of Urban Air Toxics Sources in Support of HAPs Emission Control Strategies

EPA Grant Number: R827927
Title: Characterization of Urban Air Toxics Sources in Support of HAPs Emission Control Strategies
Investigators:
Institution: Sri International
EPA Project Officer: Chung, Serena
Project Period: December 1, 1999 through November 30, 2002
Project Amount: $506,742
RFA: Urban Air Toxics (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air

Description:

This instrument will provide direct detection and identification of the most hazardous HAPs and HAP mixtures in urban air in real time, i.e. one to several minutes of averaging. The objectives in this combined laboratory and pilot field study are to establish a viable means of measuring the emission rates, and temporal and spatial distributions of urban air toxics and HAPs using an existing, ultra-sensitive, CEM. Because CEM is capable of directly measuring in real-time the concentration of specific HAPs and urban air toxics at levels far below present analytical instruments, the investigators will develop the capability to identify and characterize critical emission sources over a wide geographical area under a variety of ambient monitoring conditions. We will use this capability in a pilot field study to validate our approach to measurement and characterization of urban air toxics.

To extend the capabilities and detection limits of our instrument, the investigators will perform laboratory measurements of the REMPI spectra for a selected subset of the HAPs using the instrument. The table below lists 27 organic HAPs that have previously been detected using jet-REMPI at concentrations well below anticipated ambient urban levels. The investigators will expand this list to include numerous additional aliphatic, chlorinated, oxygenated, and aromatic hydrocarbons species.

Approach:

This instrument will provide direct detection and identification of the most hazardous HAPs and HAP mixtures in urban air in real time, i.e. one to several minutes of averaging. The objectives in this combined laboratory and pilot field study are to establish a viable means of measuring the emission rates, and temporal and spatial distributions of urban air toxics and HAPs using an existing, ultra-sensitive, CEM. Because CEM is capable of directly measuring in real-time the concentration of specific HAPs and urban air toxics at levels far below present analytical instruments, the investigators will develop the capability to identify and characterize critical emission sources over a wide geographical area under a variety of ambient monitoring conditions. We will use this capability in a pilot field study to validate our approach to measurement and characterization of urban air toxics.

To extend the capabilities and detection limits of our instrument, the investigators will perform laboratory measurements of the REMPI spectra for a selected subset of the HAPs using the instrument. The table below lists 27 organic HAPs that have previously been detected using jet-REMPI at concentrations well below anticipated ambient urban levels. The investigators will expand this list to include numerous additional aliphatic, chlorinated, oxygenated, and aromatic hydrocarbons species.

Benzene	Toluened	Phenol
o-Xylene	m-Xylene	p-Xylene
o-Xylene	m-Cresol	p-Cresol
Chlorobenzene	o-Chlorotoluene	m-Chlorotoluene
p-Chlorotoluene	Naphthalene	o-Dichlorobenzene
m-Dichlorobenzene	p-Dichlorobenzene	2,4-Dichlorotoluene
2,5-Dichlorotoluene	2,6-Dichlorotoluene	3,4-Dichlorotoluene
Dibenzofuran	Dibenzodioxin	2-Chlorodibenzodioxin
2,3-Dichlorodibenzodioxin	2,7-Dichlorodibenzodioxin	2,8-Dichlorodibenzodioxin

The specific compounds investigated will be selected based on their relative contribution to the human exposure models, their expected prevalence in polluted urban air, and their known or suspected toxicity. Based on our laboratory data, we will conduct a limited, pilot-scale, field study of HAPs emissions by transporting our instrument to a variety of urban and industrial sites in the San Francisco Bay Region. Results from parallel sampling and chemical analysis by traditional methods will be compared with the averages of our real-time data to benchmark our measurements. Knowledge obtained during this pilot field program will be essential to a future goal of designing ruggedized, portable, field instruments.

Expected Results:

Because of the unequalled temporal resolution and sensitivity of our instrument, this study will provide the only reliable, real-time, data set on the concentration and distribution of numerous HAPs in polluted urban air. Spatial and temporal mapping of HAPs levels as a function of meteorological, seasonal, and atmospheric conditions will establish a means to identify emissions trends, determine human exposure levels, and assess the increased risks associated with specific geographical areas or subpopulations. It will permit experiments to rapidly determine cause and effect relationships between HAPs emissions and the operational conditions of their sources.
An important result of this effort will be the design of a field deployable instrument based on our approach that can be used in a subsequent comprehensive field study of urban air toxics linked to epidemiological or health effects studies. These studies will provide the scientific basis for regional or national emissions control strategies and standards. Once these exposure levels are measured using the techniques established in this effort, they will contribute to a significant improvement in the ability to link exposure and risk associated with urban air toxics.

In addition to making HAPs concentration measurements, we will also study the temporal variation and interconversion of related chemical species with exposure to sunlight and other meteorological conditions. This will provide direct information on atmospheric transformations of emitted HAPs by photolytic processes. This aspect is often neglected in urban pollution studies, but is crucial to establishing the identity of those compounds actually causing toxic effects. Such transformation studies can be enhanced by correlating our real-time HAPs and transformed HAPs levels with short-term, local, variations in oxidizing potential as indicated by ambient ozone levels measured independently using off-the-shelf instrumentation.

Publications and Presentations:

Publications have been submitted on this project: View all 8 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 4 journal articles for this project

Supplemental Keywords:

VOC, PAH, PCB, PNA, dioxin, furan, environmental chemistry, physics, risk assessment, chemical transformation, epidemiology., RFA, Scientific Discipline, Air, Toxics, air toxics, Environmental Chemistry, HAPS, Chemistry, chemical mixtures, tropospheric ozone, 33/50, ambient air quality, emission control strategies, urban air toxics, urban air, stratospheric ozone, air pollutants, Toluene, hydrocarbon, Xylenes, hazardous air pollutants, benzene, chemical composition, urban air pollutants, Cresols/Cresylic acid (isomers and mixture), furans, acute toxicity, hydrocarbons, Benzene (including benzene from gasoline), Xylenes (isomers and mixture), atmospheric chemistry

Progress and Final Reports:

2000 Progress Report

2001 Progress Report

Final Report