Understanding Air Pollutants
The EPA monitors six criteria air pollutants that can harm your health and the environment. Learn about each pollutant, its sources, and health effects.
Carbon Monoxide (CO)
EPA Standard: 9.0000 ppm
Carbon monoxide is a colorless, odorless gas emitted from combustion processes. At very high levels, which are possible indoors or in other enclosed environments, CO can be poisonous or even fatal.
Nitrogen Dioxide (NO₂)
EPA Standard: 53.0000 ppb
Nitrogen dioxide is a highly reactive gas that forms from emissions from cars, trucks, buses, power plants, and off-road equipment. NO₂ is also a precursor to ozone formation and particulate matter.
Ozone (O₃)
EPA Standard: 0.0700 ppm
Ground-level ozone is not emitted directly into the air but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. This is different from the protective ozone layer in the upper atmosphere.
PM10 (Coarse Particulate Matter)
EPA Standard: 150.0000 µg/m³
PM10 includes inhalable particles with diameters that are 10 micrometers and smaller. These particles are about 5 times smaller than the width of a human hair and include dust, pollen, and mold spores.
PM2.5 (Fine Particulate Matter)
EPA Standard: 12.0000 µg/m³
PM2.5 refers to atmospheric particulate matter with a diameter of less than 2.5 micrometers. These tiny particles are about 30 times smaller than the width of a human hair and can penetrate deep into your lungs and even enter your bloodstream.
Sulfur Dioxide (SO₂)
EPA Standard: 75.0000 ppb
Sulfur dioxide is a gas primarily emitted from fossil fuel combustion at power plants and other industrial facilities. It is also emitted from locomotives, ships, and other vehicles and equipment that burn fuel with a high sulfur content.
How Air Quality Affects Your Health
Air pollution affects people differently based on age, health conditions, and exposure levels. Children, elderly people, and those with respiratory or heart conditions are most at risk.
Who's Most at Risk?
- •Children and teenagers
- •Adults 65 years and older
- •People with heart or lung disease
- •People with asthma or allergies
- •Pregnant women
- •Outdoor workers and athletes
Common Health Effects
- •Coughing and throat irritation
- •Difficulty breathing deeply
- •Chest pain and wheezing
- •Increased asthma attacks
- •Increased risk of respiratory infections
- •Aggravated heart conditions
Stay Protected
Check your local air quality daily and follow health recommendations, especially on high pollution days. Consider using air purifiers indoors and limiting outdoor activities when AQI levels are elevated.
Check Your Local AQI →