(This page last updated on October 22, 2014)

Emission Inventory Source Category
Miscellaneous Processes / Road Dust / Paved Entrained Road Dust

Emission Inventory Codes (EIC) CES Codes  Description
 640-635-5400-0000 83618  Freeways
 640-637-5400-0000 83626  Major Streets
 640-639-5400-0000 83634  Collector Streets
 640-641-5400-0000 83642  Local Streets
 640-643-5400-0000 89656  Rural Streets
 640-636-5400-0000 47456  Unspecified Paved Roads

Method Summary: This category includes 2008 estimates of fugitive dust particulate matter entrained by vehicular travel on paved roads. Road dust emissions are estimated for freeways and expressways, major streets and highways, collector streets, local streets, rural streets and unspecified paved roads. Vehicle exhaust, brake wear, and tire wear are computed separately as part of the mobile source emission inventory.

Activity Data Source: County-specific vehicle miles traveled (VMT) on paved roads are from the Air Resources Board's on-road emission inventory model, EMFAC2011-SG and air districts. Caltrans'  Highway Performance Monitoring System (HPMS) data are used to estimate the fraction of travel on freeways, major, collector and local streets in each county. VMT for unspecified paved roads are provided by counties or air districts.

Emission Factor Source: The emission factor and emission factor equation used are from EPA's AP-42 document, Section 13.2.1 (Jan. 2011). California specific roadway silt loading inputs were measured by Midwest Research Institute, University of California, Davis, and University of California, Riverside, from 1995-1997. A default average vehicle fleet weight value of 2.4 tons is used statewide. Western Regional Climate Center data were used to adjust emissions for annual days of rainfall.

Temporal Data: Temporal data is the same as is used for the on-road motor vehicle exhaust emissions because it tracks overall vehicular activity. Daily activity has peaks at 7:00 a.m. and 4:00 p.m., with less activity at other hours. Weekly activity dips slightly on the weekends.  Monthly activity for each county/air basin/district is based on monthly and annual days of rainfall, with decreases during the winter months.

Changes in Method and Emissions Estimates
: This update uses a revised emission factor equation from U.S EPA’s January 2011 update to AP-42 13.2.1. The revised emission factor equation eliminates the “C” factor (which previously double-counted tire wear, brake wear and exhaust emissions with the mobile inventory), uses an updated particle size profile and incorporates a rainfall adjustment. Activity data were updated, new temporal profiles were developed, and the growth surrogate was revised. 

Date of Last Update: April 2014

Growth Parameter: Emissions for all roads except unspecified roads are grown based on changes in VMT.  No growth is assumed for unspecified roads.

Statewide Emissions Summary
(2008 — Annual Average Tons / Day, Uncontrolled)

640-635-5400-0000 0.00 0.00 0.00 0.00 29.89
640-637-5400-0000 0.00 0.00 0.00 0.00 41.24
640-639-5400-0000 0.00 0.00 0.00 0.00 9.57
640-641-5400-0000 0.00 0.00 0.00 0.00 55.76
640-643-5400-0000 0.00 0.00 0.00 0.00 25.30
640-636-5400-0000 0.00 0.00 0.00 0.00  7.26
Total 0.00 0.00 0.00 0.00 169.03

                   Area Source Top Page             Search ARB Programs / Topics