What are the 6 criteria air pollutants?

6 criteria air pollutants: A benchmark for better air quality

These criteria are meant to help evaluate evaluate indoor air quality, outdoor air pollution, and overall air quality — and eventually act to reduce particle pollution

The criteria refers to specific contaminants that serve as key indicators for air quality — and are therefore regulated by agencies. Although these specific contaminants are regulated as part of clean air standards across the globe, the term “criteria air pollutants” refers specifically to US programs under the Clean Air Act (1970).

In the US, the identified pollutants serve as a base for one of the country’s primary regulatory programs under the US Clean Air Act, namely, the National Ambient Air Quality Standards (NAAQS).

The EPA organizes NAAQS into two types of standards, established for each of the criteria air pollutants:

1. Primary, referring to human health
2. Secondary, referring to welfare (e.g., environment, livestock, and property)

After the United States’ mandates were made public, several countries soon followed, striving to align on global air quality standards.

The 6 criteria air pollutants

EPA determined the most crucial air pollutants to evaluate, monitor, and mitigate to improve air quality.

Since 1978, the list has remained essentially unchanged in the US. And the same pollutants appear as part of similar lists of standards across other regions, namely the EU.

Here’s an overview of the six emissions causing the worst particle pollution to add to your company’s watch list:

1.Carbon monoxide

Carbon monoxide (CO) is primarily emitted by vehicles and gasoline-burning equipment, such as generators. Carbon monoxide can also be released as part of various industrial processes, including food, chemical, and metal manufacturing.

When inhaled at elevated levels, CO can reduce the amount of oxygen in the blood, which can lead to dizziness and even death. More commonly, CO causes complications for people with heart conditions, including reducing oxygen to the heart, and chest pain.

2. Lead

Common sources of this criteria air pollutant include ore and metal processing, waste incinerators, and lead-acid battery manufacturing.

Historically, one of the largest sources of lead in the air was the burning of leaded gasoline by vehicles. Lead is a probable human carcinogen and exposure can also lead to developmental effects in children, including lowered IQ.

3. Nitrogen dioxide

Nitrogen dioxide, (NO_2), like CO, is emitted by vehicles as well as electrical generating equipment and non-road engines that burn gasoline.

NO₂ exposure can cause a host of health effects, especially for people with respiratory diseases, such as asthma. Inhaling even small quantities can lead to wheezing, coughing, difficulty breathing, or overall reduced lung function, which is severe enough to require hospitalization. Extended exposure can even lead to the development of asthma in healthy individuals.

4. Ground-level ozone

Ground-level ozone (O₃) isn’t directly emitted by human processes. However, it’s produced by the interaction of nitrogen oxides and volatile organic compounds (VOCs), which are common industrial emissions.

Exposure to ozone can cause difficulty breathing and damage to the airways. As with other pollutants, O₃ can aggravate asthma and other lung diseases when inhaled.

5. Particulate matter

Particulate matter (PM) refers to a broad set of pollutants generally grouped based on the size of the emitted particles.

These groups include particles smaller than 2.5 micrometers (PM2.5) and those between 10 and 2.5 micrometers (PM10). Sources of these particles vary but often include farming operations, combustion sources, construction, and various industrial processes.

According to the EPA, PM exposure can lead to a host of dangerous health effects including heart attacks and irregular heartbeat, increased respiratory symptoms and aggravated asthma, as well as premature death in people with heart or lung disease.

6. Sulfur dioxide

Sulfur dioxide, abbreviated as SO₂, this criteria air pollutant is primarily emitted by electrical generation sources that burn sulfur-containing fuels as well as metal processing and smelting facilities.

Exposure to SO₂ can lead to difficulty breathing, wheezing, and shortness of breath. Even short-term exposures can be associated with hospitalizations for respiratory-related symptoms.

Regulatory activity around criteria air pollutants

While the set of criteria air pollutants stays relatively the same, regulatory activity around them is ever evolving. Much of the regulatory activity revolves around the designation of areas as either “attainment” or “nonattainment” for the NAAQS for each of the six pollutants. This is due to their potentially wide-ranging effects on communities, the environment, and regulated industries.

Agencies tasked with issuing air permits in nonattainment areas — that is, areas where the ambient air quality is worse than the health-based primary standards, the welfare-based secondary standards, or both — are required under the CAA to impose tougher controls on sources than those in attainment.

Prioritizing criteria air pollutants in your company

While reducing emissions from criteria air pollutants is only one way companies are charged with helping to improve air quality, it’s a significant one.

Keeping track of the emissions at your facilities as well as the attainment status at your sites can go a long way in meeting obligations to keep you well prepared for when it comes time to renewing your air permit.