National Ambient Air Quality Standards (NAAQS)

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Why this Information Is Important: National Ambient Air Quality Standards (NAAQS) set legal limits for air pollutants like PM2.5 and PM10 (dust). To prove a violation of these standards, measurements must come from official regulatory air monitors run by the Virginia Department of Environmental Quality (VA DEQ). However, no such monitors have ever been placed in Southeast Newport News or Lambert's Point. Because coal dust contains toxic metals and health experts agree there is no safe level of PM2.5, people can still be harmed even when PM2.5 and PM10 levels meet the NAAQS. Understand why the lack of regulatory air monitoring prevents enforcement and why more air monitoring and stronger protections are needed.

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Overview

The Clean Air Act is the primary federal law governing air pollution in the U.S.[1] The Clean Air Act gives the U.S. Environmental Protection Agency (EPA) authority to set and enforce limits on atmospheric levels of harmful air pollutants, including particulate matter like coal dust.

The EPA has identified six "criteria pollutants" that must not exceed concentration thresholds known as the National Ambient Air Quality Standards (NAAQS), pronounced as "the nacks." The criteria pollutants are fine particulate matter (PM2.5) and coarse particulate matter (PM10), also known as dust, as well as ozone (O3), lead (Pb), carbon monoxide (CO), sulfur dioxide (SO2), and nitrogen dioxide (NO2).

To determine NAAQS compliance, atmospheric concentrations of criteria pollutants must be measured using designated regulatory air monitors by an agency with the authority to do so, which in Virginia is the Virginia Department of Environmental Quality (VA DEQ). When locations exceed the NAAQS for any of the criteria pollutants, regulatory action is triggered, including stricter permitting requirements for nearby industries, emission reductions plans, enforcement measures, and public health advisories.

Particulate Matter

PM10: The PM10 NAAQS is a 24-hour average mass concentration of 150 μg/m3, not to be exceeded more than three times over three years.[2]
PM2.5: There are two PM2.5 NAAQS: a 24-hour average mass concentration of 35 μg/m3 and a recently revised annual average mass concentration of 9 μg/m3.[2]

The NAAQS are set to protect public health, including the health of more sensitive individuals such as those with asthma as well as children and elders. That said, there is no known safe level of exposure to PM2.5, with documented health impacts below the NAAQS.[3]

Limitations

Where Are Monitors Located?: The location of these regulatory air monitors is critical. However, the VA DEQ has never operated such monitors in Southeast Newport News or Lambert's Point. The VA DEQ currently measures PM10 at just two locations in Hampton Roads: one monitor at NASA Langley Research Center in Hampton and one monitor at the NOAA Storage Facility in Norfolk. Both monitors are too far away from the coal export terminals to routinely record evidence of airborne coal dust. In 2015, the Southeast CARE Coalition collected 1000 signatures and petitioned the VA DEQ to install regulatory air monitors in Southeast Newport News, but the VA DEQ ignored the petition.
Are the NAAQS Protective?: First, coal dust typically contains high levels of toxic metals, including mercury (Hg), lead (Pb), arsenic (Ar), cadmium (Cd), as well as crystalline silica. These substances are harmful when inhaled or ingested and are known to cause cancer, fetal defects, and neurological damage, even at very low doses. Coal dust also contains high levels of transition metals, including iron (Fe), manganese (Mn), and copper (Cu) that can induce oxidative stress in our bodies. Because coal dust has high concentrations of metals, there is reason to believe it causes harm at exposures below PM10 NAAQS, with there being no safe level of PM2.5 composed of any material.
Second, wind-blown coal dust includes many particles that are larger than PM10, with PM10 defined as the total amount of particles with a diameter equal to or less than 10 micrometers. This means the vast majority of the mass of coal dust particles that deposit into Southeast Newport News and Lambert's Point are not actually considered an air pollutant under the NAAQS.

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Sources

  1. ↑ Evolution of the Clean Air Act, November 12, 2024.
  2. ↑ 2.0 2.1 NAAQS Table, U.S. EPA, Undated.
  3. ↑ Makar et al., Estimating the Causal Effect of Low Levels of Fine Particulate Matter on Hospitalization, Epidemiology, 28, 5, 627–634, 2017.
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