Diesel Particulate Matter

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 these 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 this indicator 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. These include irritation to the eyes, throat and nose, heart and lung disease, and lung cancer.
Children and the elderly are especially vulnerable to the effects of diesel PM.

How is diesel particulate matter measured in CalEnviroScreen 4.0?

The California Air Resources Board (ARB) collects estimates of diesel PM emissions from many sources.
The indicator uses CARB data on emissions from on-road (trucks and buses) and off-road (ships and trains, for example) sources.
Diesel emissions are available at a 1x1km grid statewide. The gridded emissions are converted to census tracts.
Adjustments to diesel PM emissions from idling trucks in Mexico at the U.S. border crossings were also accounted for.

A complete description of the Diesel PM indicator can be found in the CalEnviroScreen 4.0 report.