US EPA finalizes NAAQS for particulate matter

8 December 2020

The US Environmental Protection Agency (EPA) announced its final decision to retain the existing National Ambient Air Quality Standards (NAAQS) for particulate matter (PM) set in 2015 by the previous US administration.

These NAAQS standards for particulate matter include:

• Primary (health) standards for fine particles (PM_2.5):
  • An annual average standard of 12.0 μg/m³.
  • A 24-hour standard of 35 μg/m³.
• Primary (health) standard for coarse particles (PM₁₀)—A 24-hour standard of 150 μg/m³.
• Secondary (welfare) standards for particle pollution—EPA’s secondary standards for particle pollution are identical to the primary standards for PM_2.5 and PM₁₀, except for the secondary annual PM_2.5 standard which has a level of 15.0 μg/m³.

The US NAAQS standards for PM are relatively stringent compared to other jurisdictions. The European Union, for instance, has an annual PM_2.5 standard of 25 μg/m³, more than twice the US EPA standard of 12 μg/m³. The WHO air quality guideline for ambient PM_2.5 is 10 μg/m³—a value adopted as an ambient air quality standard in Australia, Canada, Iran, Switzerland, UK, and some other countries.

The EPA decision not to increase the stringency of existing PM standards was criticized by some public health advocates, such as the Natural Resources Defense Council (NRDC), and praised by some industry groups, such as the American Petroleum Institute (API).

The EPA is under legal obligation to review the NAAQS every five years to determine whether they should be retained or revised.

Source: US EPA