AQ Monitoring Results: Crockett: Particulate Matter (PM10) at John Swett

This page last reviewed September 27, 2010

Background

Particulate matter is a major air pollutant consisting of tiny solid or liquid particles of soot, dust, smoke, fumes, or mists. The particulate matter with a size of 10 microns or smaller (about 0.0004 inches or less) is normally referred to as PM10. The size of PM10 allows the pollutant to reach deep in the lungs, where they may be deposited to result in adverse health effects.

Both national and state standards have been established for PM10. The standards are levels above which PM10 is known to cause adverse health in humans. The current standards are:

Averaging Time California Standards National Standards
24-hour 50 ug/m3 150 ug/m3
Annual Mean (Arithmetic Mean) 20 ug/m3 (Arithmetic Mean) 50 ug/m3

Currently over 99% of all Californians are breathing air that violates the state PM10 standards.

Particulate matter can be directly emitted or can be formed in the atmosphere when gaseous pollutants such as sulfur dioxide (SO2) and nitrogen dioxide (NO2) undergo chemical reactions in the atmosphere. Major sources of PM10 in California include:

  • motor vehicles (5%)
  • area wide sources: windblown dust from open lands, dust from construction, landfills and agriculture, wood burning stoves and fireplaces, wildfires and brush/waste burning (total 89%)
  • industrial sources (6%)

From year 1990 to 2000, overall PM10 emissions increased as the population went up. The diesel particulate matter, which imposes the most significant risk to human health, has dropped 40% from 1990 to 2000 due to stringent emission standards and the introduction of cleaner diesel fuel.

Ambient Monitoring Results

Ambient levels of PM10 are routinely monitored at approximately 150 sites in the California ambient air quality measurement network. The statewide average concentration of PM10 during 1998-2000 was 29 ug/m3 (micrograms per cubic meter). Relative to the statewide average, the Contra Costa County region was 34% lower for the same time period, averaging 19 ug/m3.

The ambient monitoring results at John Swett are provided here:

  • A graph comparing the monthly summaries of PM10 in the community with historical statewide and regional levels
  • A table of summary statistics
  • Raw data in Excel format

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