National Ambient Air Quality Standard

On February 7, 2024, the U.S. Environmental Protection Agency (EPA) released its Final Rule lowering the primary annual National Ambient Air Quality Standard (NAAQS) for fine particulate matter (PM 2.5) from the current level of 12 micrograms per cubic meter (μg/m3) to 9 μg/m3.  Once published, the Final Rule is certain

On January 6, 2023, the U.S. Environmental Protection Agency (EPA) released a pre-publication copy of a Proposed Rule, which will lower the annual National Ambient Air Quality Standard (NAAQS) for fine particulate matter (PM2.5). PM2.5 refers to PM with a diameter of 2.5 microns or less, which is about 3-5 percent