National Ambient Air Quality Standards (NAAQS): Difference between revisions

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The Clean Air Act is the primary federal law governing air pollution in the United States, passed first 1970.<ref>[https://web.archive.org/web/20250618033034/https://www.epa.gov/clean-air-act-overview/evolution-clean-air-act Evolution of the Clean Air Act.] November 12, 2024.</ref> It gives the [[U.S. Environmental Protection Agency (EPA)|EPA]] authority to set limits on harmful pollutants, including [[Particulate matter and coal dust|particulate matter]] like coal dust, and to enforce these standards nationwide. Because they are harmful to our health, airborne particles are regulated as part of the Clean Air Act.
The [https://www.epa.gov/laws-regulations/summary-clean-air-act Clean Air Act] is the primary federal law governing air pollution in the U.S.<ref>[https://web.archive.org/web/20250618033034/https://www.epa.gov/clean-air-act-overview/evolution-clean-air-act Evolution of the Clean Air Act.] November 12, 2024.</ref> 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 and Coal Dust|particulate matter]] like [[Particulate Matter and Coal Dust|coal dust]].  


== National Ambient Air Quality Standards ==
The [[U.S. Environmental Protection Agency (EPA)|EPA]] has identified six "criteria pollutants" that must not exceed concentration thresholds known as the [https://www.epa.gov/criteria-air-pollutants/naaqs-table National Ambient Air Quality Standards (NAAQS)], pronounced as "the nacks". The criteria pollutants are [[Particulate Matter and Coal Dust|fine particulate matter (PM<sub>2.5</sub>)]] and [[Particulate Matter and Coal Dust|coarse particulate matter (PM<sub>10</sub>)]], also known as [[Particulate Matter and Coal Dust|dust]], as well as ozone (O<sub>3</sub>), lead (Pb), carbon monoxide (CO), sulfur dioxide (SO<sub>2</sub>), and nitrogen dioxide (NO<sub>2</sub>).  
The [[Regulatory Agencies#U.S. Environmental Protection Agency (EPA)|U.S. Environmental Protection Agency (EPA)]] controls six criteria pollutants that must not exceed concentration thresholds known as the [https://www.epa.gov/criteria-air-pollutants/naaqs-table National Ambient Air Quality Standards (NAAQS)], often pronounced as "the nacks". The six criteria air pollutants (CAP) for which limits are set in the NAAQS are ozone (O3), [[Particulate matter and coal dust|atmospheric particulate matter (PM2.5/PM10)]], lead (Pb), carbon monoxide (CO), sulfur oxides (SOx), and nitrogen oxides (NOx).<ref>[https://web.archive.org/web/20200229013911/https://www.des.nh.gov/organization/commissioner/pip/factsheets/ard/documents/ard-41.pdf EPA Criteria Air Pollutants]. ''New Hampshire Department of Environmental Sciences.'' 2019. </ref> These are typically emitted from many sources in industry, mining, transportation, electricity generation and agriculture. In many cases they are the products of the combustion of fossil fuels or industrial processes. Exceeding these thresholds can trigger regulatory action, including stricter permitting requirements and enforcement measures


=== Particulate Matter under NAAQS ===
To determine NAAQS compliance, atmospheric concentrations of criteria pollutants must be measured using designated [[General Air Monitoring|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, emission reductions plans, enforcement measures, and public health advisories.  
The [[Particulate matter and coal dust|PM<sub>10</sub>]] NAAQS is a 24-hour average mass concentration of 150 μg/m<sup>3</sup>, not to be exceeded more than three times over three years.<ref name=":0">U.S. EPA, [https://www.epa.gov/criteria-air-pollutants/naaqs-table NAAQS Table].</ref> There are two [[Particulate matter and coal dust|PM<sub>2.5</sub>]] NAAQS: a 24-hour average mass concentration of 35 μg/m<sup>3</sup> and a recently revised annual average mass concentration of 9 μg/m<sup>3</sup>.<ref name=":0" /> The NAAQS are set to protect public health, including the health of more sensitive individuals such those with asthma as well as children and elders. That said, there is no known safe level of exposure to [[Particulate matter and coal dust|PM<sub>2.5</sub>]], with documented health impacts below the NAAQS.<ref>Makar et al., [https://journals.lww.com/epidem/abstract/2017/09000/estimating_the_causal_effect_of_low_levels_of_fine.1.aspx Estimating the Causal Effect of Low Levels of Fine Particulate Matter on Hospitalization], ''Epidemiology'', 28, 5, 627–634, 2017.</ref>


== Monitoring and Compliance ==
=== Particulate Matter ===
Compliance with the Clean Air Act is determined through a combination of air quality monitoring, emissions reporting, and regulatory inspections.


* '''Monitoring:''' To determine NAAQS compliance, [[Particulate matter and coal dust|PM<sub>2.5</sub>]] and [[Particulate matter and coal dust|PM<sub>10</sub>]] must be measured using designated [[Air monitoring#Regulatory Air Monitoring|regulatory air monitors]] by an agency with the authority to do so, which in Virginia is the [[Regulatory Agencies#Virginia Department of Environmental Quality (VA DEQ)|Department of Environmental Quality (VA DEQ)]].
* The [[Particulate Matter and Coal Dust|PM<sub>10</sub>]] NAAQS is a 24-hour average mass concentration of 150 μg/m<sup>3</sup>, not to be exceeded more than three times over three years.<ref name=":0">U.S. EPA, [https://www.epa.gov/criteria-air-pollutants/naaqs-table NAAQS Table].</ref>
* There are two [[Particulate Matter and Coal Dust|PM<sub>2.5</sub>]] NAAQS: a 24-hour average mass concentration of 35 μg/m<sup>3</sup> and a recently revised annual average mass concentration of 9 μg/m<sup>3</sup>.<ref name=":0" />
The NAAQS are set to protect public health, including the health of more sensitive individuals such those with asthma as well as children and elders. That said, there is no known safe level of exposure to [[Particulate Matter and Coal Dust|PM<sub>2.5</sub>]], with documented health impacts below the NAAQS.<ref>Makar et al., [https://journals.lww.com/epidem/abstract/2017/09000/estimating_the_causal_effect_of_low_levels_of_fine.1.aspx Estimating the Causal Effect of Low Levels of Fine Particulate Matter on Hospitalization], ''Epidemiology'', 28, 5, 627–634, 2017.</ref>


* '''Permitting and Reporting:''' Facilities must obtain air [[Terminal Permits|permits]] that set specific emissions limits and require regular reporting of emissions data.
=== Limitations ===
 
== Documents ==
* '''Inspections and Enforcement:''' Agencies like the EPA or state departments (e.g., Virginia DEQ) conduct inspections and reviews. Violations can result in penalties or mandatory corrective actions.
 
=== NAAQS Compliance ===
Air quality is continuously monitored through a network of state and federal stations. If an area exceeds the standards, it may be designated as a “nonattainment area.” This designation triggers a series of regulatory steps aimed at reducing pollution, including:
* Emissions reduction plans
* Industry-specific control measures
* Public health advisories
Coal handling facilities and mining operations are often required to implement dust control technologies such as water sprays, windbreaks, and enclosures to minimize their contribution to PM levels.


== References ==
== References ==

Latest revision as of 08:01, 28 January 2026

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, emission reductions plans, enforcement measures, and public health advisories.

Particulate Matter

  • 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]
  • 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 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

Documents

References

  1. ↑ Evolution of the Clean Air Act. November 12, 2024.
  2. ↑ 2.0 2.1 U.S. EPA, NAAQS Table.
  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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