Aoñsndxjknsa

SECTION 1 INTRODUCTION The document "Compilation of Air Pollutant Emissions Factors" (AP-42) has been published by the U.S. Environmental Protection Agency (EPA) since 1968. Supplements to AP-42 have been routinely published to add new emission source categories and to update existing emission factors. AP-42 is periodically updated by EPA to respond to new emission factor needs of EPA, State, andlocal air pollution control programs and industry. An emission factor relates the quantity (weight) of pollutants emitted to a unit of activity of the source. The uses for the emission factors reported in AP-42 include: 1. Estimates of area-wide emissions. 2. Estimates of emissions for a specific facility. 3. Evaluation of emissions relative to ambient air quality. The purpose of this report isto compile the existing background report and supplements into a single report, provide an update of the background information from test reports and other information to support preparation of a revised AP-42 section to replace existing Section 13.2.1, "Paved Roads," dated November 2006. The principal pollutant of interest in this report is “particulate matter” (PM), with special emphasis placedon “PM10” - particulate matter no greater than 10μmA (micrometers in aerodynamic diameter) and PM2.5. PM10 and PM2.5 form the basis for the current National Ambient Air Quality Standards (NAAQSs) for particulate matter. PM10 and PM2.5 thus represent the two size ranges of particulate matter that are of greatest regulatory interest. Nevertheless, formal establishment of PM10 and PM2.5 as thestandard basis is relatively recent, and many emission tests have referenced other particle size ranges. Other size ranges employed in this report are:

TSP Total Suspended Particulate, as measured by the standard high-volume (hi-vol) air sampler. TSP was the basis for the previous NAAQSs for particulate matter. TSP consists of a relatively coarse particle size fraction. While the particle capturecharacteristics of the hi-vol sampler are dependent upon approach wind velocity, the effective D50 (i.e., 50% of the particles are captured and 50% are not) varies roughly from 25 to 50 μmA. SP Suspended Particulate, which is used as a surrogate for TSP. Defined as PM no greater than 30 μmA. SP also may be denoted as “PM30.” IP Inhalable Particulate, defined as PM no greater than 15 μmA. Throughoutthe late 1970s and the early 1980s, it was clear that EPA intended to revise the NAAQSs to reflect a particle size range finer than TSP. What was not clear was the size fraction that would be eventually used, with values between 7 and 15 μmA frequently mentioned. Thus, many field studies were conducted using IP emission measurements because it was believed that IP would be the basis for the newNAAQS. IP may also be represented by “PM15.”

FP Fine Particulate, defined as PM no greater than 2.5μmA. FP also may be denoted as “PM2.5.” This background report consists of five sections. Section 1 provides an introduction to the report. Section 2 presents descriptions of the paved road source types and emissions from those sources as well as a brief history of the current AP-42 emission factors.Section 3 is a review of emissions data collection and analysis procedures; it describes the literature search, the screening of emission test reports, and the quality rating system for both emission data and emission factors. Section 4 details the development of paved road emission factors for the draft AP-42 section; it includes the review of specific data sets and the results of data analysis.Section 5 presents the AP-42 section for paved roads. SECTION 2 SOURCE DESCRIPTION Particulate emissions occur whenever vehicles travel over a paved surface, such as public and industrial roads and parking lots. These emissions may originate from material previously deposited on the travel surface, resuspension of material carried by the vehicle, deposits from undercarriages, engine exhaust...