In response to a court order, the US Environmental Protection Agency (EPA) finalized an update to its national air quality standards for harmful fine particle pollution (PM2.5), including soot, setting the annual health (primary) standard at 12 µg/m3. The outgoing annual standard is 15 µg/m3, which has been in place since 1997. (Earlier post.)
The ruling has no effect on the existing daily primary standard for fine particles (35 μg/m3) or the existing 24-hour health and environmental (primary and secondary) standards for coarse particles (PM10), which have been in place since 1987 and remain unchanged at a level of 150 μg/m3.
EPA is also retaining the existing secondary standards (environmental) for PM2.5 to address PM-related effects such as visibility impairment, ecological effects, damage to materials and climate impacts. This includes an annual standard of 15.0 μg/m3 and a 24-hour standard of 35 μg/m3. The agency is relying on the existing secondary 24-hour PM2.5 standard to protect against visibility impairment, and is not finalizing the separate standard to protect visibility the EPA proposed in June 2012.
EPA had proposed to set a separate secondary 24-hour standard to provide protection against PM-related visibility effects; however, after considering public comment on the proposal and further analyzing recent air quality monitoring data, the agency has concluded that the current secondary 24-hour PM2.5 standard of 35μg/m3 will provide visibility protection that is equal to, or greater than, 30 deciviews, the target level of protection the agency is setting today. (A deciview is a yardstick for measuring visibility.)
EPA expects that fewer than 10 counties, out of the more than 3,000 counties in the United States, will need to consider any local actions to reduce fine particle pollution in order to meet the new standard by 2020, as required by the Clean Air Act. The rest can rely on air quality improvements from federal rules already on the books to meet this new standard, the agency said.
Fine particle pollution can penetrate deep into the lungs and has been linked to a wide range of serious health effects, including premature death, heart attacks, and strokes, as well as acute bronchitis and aggravated asthma among children. A federal court ruling required EPA to update the standard based on best available science.
EPA said that the standard, which comes in at the lower end of the range proposed in June, is consistent with the advice from the agency’s independent science advisors, and is based on an extensive body of scientific evidence that includes thousands of studies—including many large studies which show negative health impacts at lower levels than previously understood.
It also follows extensive consultation with stakeholders, including the public, health organizations, and industry, and after considering more than 230,000 public comments.
By 2030, EPA expects that all standards that cut PM2.5 from diesel vehicles and equipment alone will prevent up to 40,000 premature deaths, 32,000 hospital admissions and 4.7 million days of work lost due to illness.
Because reductions in fine particle pollution have direct health benefits including decreased mortality rates, fewer incidents of heart attacks, strokes, and childhood asthma, the PM2.5 standards announced today have major economic benefits with comparatively low costs, the agency said. EPA estimates health benefits of the revised standard to range from $4 billion to over $9 billion per year, with estimated costs of implementation ranging from $53 million to $350 million.
While EPA cannot consider costs in selecting a standard under the Clean Air Act, those costs are estimated as part of the analysis undertaken for all significant regulations, as required by Executive Order 13563 issued by President Obama in January 2011.
The Clean Air Act requires EPA to review its air quality standards every five years to determine whether the standards should be revised. The law requires the agency to ensure the standards are “requisite to protect public health with an adequate margin of safety” and “requisite to protect the public welfare.” A federal court required EPA to issue final standard by 14 December, because the agency did not meet its five-year legal deadline for reviewing the standards.