Diesel Particulate Matter
Exposure Indicator
Estimates diesel exhaust emissions that communities breathe—a carcinogenic pollutant concentrated near ports, rail yards, and freeways.
What is diesel particulate matter?
Exhaust from trucks, buses, trains, ships, and other equipment with diesel engines contains a mixture of gases and solid particles. These solid particles are known as diesel particulate matter (diesel PM). Diesel PM contains hundreds of different chemicals, many of which are harmful to health. The highest levels of diesel PM are near ports, rail yards, and freeways. People are exposed to diesel PM from breathing air containing diesel exhaust.
Why is it included in CalEnviroScreen?
- People living and working in cities and industrial areas and near heavy truck or train traffic are most likely to come in contact with diesel PM.
- The very small particles of diesel PM can reach deep into the lung, where they can contribute to a range of health problems, including irritation to the eyes, throat, and nose; heart and lung disease; and lung cancer.
- Diesel engine exhaust has been classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC).
- Children and the elderly are especially vulnerable to the effects of diesel PM.
How is it measured?
- The California Air Resources Board (ARB) collects estimates of diesel PM emissions from many sources.
- The indicator uses CARB data on emissions (tons/year) from on-road, area, stationary (point), and ocean-going vessel sources, using 2021 or 2022 data depending on the source.
- Diesel emissions are available at a 1x1km grid statewide. The gridded emissions are converted to census tracts.
- Adjustments are made to account for diesel PM emissions from sources on the Mexico side of the US-Mexico border that impact communities in San Diego and Imperial counties.
