Criteria Pollutants Vs. Hazardous Pollutants

With technology expanding in the United States and worldwide, air pollution is also growing. People are exposed to a number of chemicals, pesticides and other pollutants that can cause major health concerns and damage the environment. Government organizations related to health, safety and the environment have categorized air pollutants as criteria or hazardous. These pollutants differ in terms of how they are monitored, regulated and released into the environment.

Criteria Air Pollutants

• There are six criteria air pollutants identified in the United States through the Clean Air Act of 1970. They are lead, nitrogen dioxide, carbon monoxide, ozone, sulfur dioxide and particulate matter. Exposure to these substances can cause health effects, environmental effects and property damage. Health effects include heart or lung disease, respiratory damage or premature death. Environmental effects include smog, acid rain, radiation and ozone depletion.

Hazardous Air Pollutants

• There are 189 hazardous air pollutants identified by the Clean Air Act amendments of 1990. These pollutants may also be referred to as toxic air pollutants and increase the chances of developing critical health issues upon exposure such as cancer, damage to the immune system and reproductive birth defects. Some of these pollutants include asbestos, chlorine, formaldehyde, hydrochloric acid, methanol and phosphorus. The difference between criteria and hazardous air pollutants is that criteria pollutants are more common, more potent and were part of the original Clean Air Act list, and hazardous pollutants are an expansion of that list.

Air Quality Standards

• The Office of Air Quality Planning and Standards (OAQPS) collaborates with the Environmental Protection Agency (EPA) to enhance air quality and prevent contamination. The OAQPS has established the National Ambient Air Quality Standard (NAAQS), consisting of primary and secondary standards designed for each criteria pollutant. Primary standards focus on harmful health effects, and secondary standards focus on welfare effects such as vegetation and building damage. Air quality standards are measured for the six criteria pollutants, but not for hazardous pollutants. Hazardous pollutants are not monitored, but the EPA has developed regulations to limit their usage.

Emissions Data

• The National Emissions Inventory (NEI), developed by the EPA, is composed of information about the causes of criteria and hazardous air pollutant release. It includes annual estimates of emissions sources and the results of the EPA's national air pollutant inventory that is conducted every three years. Hazardous and criteria pollutants are tracked differently by the NEI. Hazardous pollutants are categorized by major emissions sources, other emissions sources (referred to as non-point), emissions deriving from on-road vehicles (such as cars) and emissions deriving from non-road vehicles (like planes or boats). Criteria pollutants are also tracked by categories of on-road and non-road vehicles; however, point and non-point sources are individually identified with detailed information for criteria pollutants and are more generalized for hazardous pollutants.

Monitoring Data

• The Air Quality System (AQS) database includes information about air pollutant motoring data derived from the EPA's 4,000 monitoring stations. These stations measure concentrations of pollutants in outdoor air daily or hourly. The AQS includes yearly summary values rather than individual estimates. Standards are measured by volume in parts per million (ppm), parts per billion (ppb), milligrams per cubic meter of air and micrograms per cubic centimeter of air. The AQS has been monitoring criteria pollutants since 1970, and most of the hazardous pollutant monitoring has taken place after 1995. This means the database contains far less information for hazardous pollutants than for criteria pollutants.