PM2.5 refers to particles in the air that are two and one half microns or less in width. Especially dangerous to human health because they bypass many of our body’s defenses.
PM10 refers to particles with a diameter of 10 micrometers (µm) or less. Because PM10 is a larger particle than PM2.5, it’s less likely to cross from the lungs into the bloodstream.
Ozone can be particularly dangerous and abundant on hot days in an urban area. Exposure to ozone can make it very difficult to breathe and cause coughing and shortness of breath.
Nitrogen dioxide is produced from combustion processes. Its presence is closely linked to the formation or presence of other air pollutants.
Sulfur dioxide is a a colorless, bad-smelling, toxic gas. It can contribute to respiratory illness by making breathing more difficult.
- Moderate (<101)
- Unhealthy (sensitive groups) (<151)
- Unhealthy (<201)
- Very unhealty (<301)
- Hazardous (301+)