Criteria pollutants are specific air pollutants that have been identified by the Environmental Protection Agency (EPA) as harmful to human health and the environment.
The term “criteria” refers to the standards or guidelines established for these pollutants to protect public health and the environment. The EPA has set National Ambient Air Quality Standards (NAAQS) for these pollutants to ensure that their levels remain within safe limits.
Criteria Pollutants
- Particulate Matter (PM)
- Types:
- PM2.5: Particles with a diameter of 2.5 micrometers or smaller. These can penetrate deep into the lungs and enter the bloodstream.
- PM10: Particles with a diameter of 10 micrometers or smaller. These can be inhaled and cause respiratory issues.
- Sources: Combustion of fossil fuels, industrial processes, vehicle emissions, construction activities.
- Health Effects: Respiratory and cardiovascular problems, aggravated asthma, lung cancer.
- Nitrogen Dioxide (NO2)
- Description: A reddish-brown gas with a pungent odor.
- Sources: Combustion of fossil fuels, industrial processes, and vehicle emissions.
- Health Effects: Respiratory problems, decreased lung function, and exacerbation of asthma.
- Sulfur Dioxide (SO2)
- Description: A colorless gas with a sharp, choking odor.
- Sources: Burning of fossil fuels, industrial processes, particularly in power plants and refineries.
- Health Effects: Respiratory issues, aggravation of asthma, and respiratory infections.
- Carbon Monoxide (CO)
- Description: A colorless, odorless gas.
- Sources: Incomplete combustion of fossil fuels, vehicle emissions, residential heating systems.
- Health Effects: Reduced oxygen delivery to the body’s organs and tissues, headaches, dizziness, and in severe cases, death.
- Ozone (O3)
- Description: A gas that occurs both in the stratosphere (ozone layer) and at ground level.
- Sources: Ground-level ozone is formed by chemical reactions between volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight.
- Health Effects: Respiratory problems, aggravation of asthma, and reduced lung function.
- Lead (Pb)
- Description: A heavy metal that can be found in particulate form in the air.
- Sources: Industrial processes, leaded gasoline (historically), and the use of lead-based paints.
- Health Effects: Neurological damage, developmental impairment in children, and cardiovascular effects in adults.
Examples and Impact
- Particulate Matter (PM2.5): In urban areas, high levels of PM2.5 can be due to traffic emissions and industrial activities. It has been linked to increased respiratory and cardiovascular diseases.
- Nitrogen Dioxide (NO2): In cities with heavy traffic, NO2 levels can be high due to vehicle emissions. Long-term exposure can lead to chronic respiratory problems.
- Sulfur Dioxide (SO2): In regions near coal-burning power plants, SO2 can be prevalent. This can cause respiratory issues and contribute to the formation of acid rain.
- Carbon Monoxide (CO): In densely populated urban areas, CO levels can rise due to vehicle emissions, particularly in congested traffic. High CO levels can lead to impaired oxygen delivery in the body.
- Ozone (O3): In sunny, polluted urban areas, ground-level ozone can reach unhealthy levels, particularly in summer. This can aggravate asthma and other respiratory conditions.
- Lead (Pb): Historically, leaded gasoline contributed to elevated lead levels in the atmosphere. Although less common now, lead from industrial sources can still be a concern, particularly in older areas with lead-based paint.
These criteria pollutants are monitored and regulated by environmental agencies to ensure that their concentrations remain within safe limits to protect human health and the environment.