Air Quality

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Air Quality Index and AQI Chart

Sun dimmed by wildfire smoke, June 6, 2023, W Groton, NY (TS)

Harmful particle pollution is one of our nation’s most common air pollutants. The U.S. AQI is EPA’s index for reporting air quality. AQI values at or below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is unhealthy: at first for certain sensitive groups of people, then for everyone as AQI values get higher.

The AQI is divided into six categories. Each category corresponds to a different level of health concern. Each category also has a specific color. The color makes it easy for people to quickly determine whether air quality is reaching unhealthy levels in their communities. Use the chart below to help reduce your exposure and protect your health. Visit AirNow.gov for Zip Code and city-level AQI forecast.

Note: The Sensitive (at-risk) group listed in this chart includes people with heart or lung disease, older adults, children and teens, minority populations and outdoor workers.

Good (0-50) (Green)

Air quality is good. It’s a great day to be outside.

Chart showing Air Quality Index (AQI) color categories

Moderate (51-100) (Yellow)

People usually sensitive to air pollution are at risk.

  • Air quality is acceptable. Consider making outdoor activities shorter and less intense. Watch for coughing or shortness of breath. These are signs to take it easier.
  • Everyone else: It's a good day to be active outside.

Unhealthy for Sensitive Groups (101-150) (Orange)

People in the sensitive group are at risk. This includes people with heart or lung disease, older adults, children and teens, minority populations and outdoor workers.

  • Sensitive group: Make outdoor activities shorter and less intense. Take more breaks. Keep medicine handy.
  • Everyone else is less likely to be affected.

Unhealthy (151-200) (Red)

Everyone is at risk.

  • Sensitive group: Avoid long or intense outdoor activities. Consider rescheduling or moving activities indoors.
  • Everyone else: Reduce long or intense outdoor activities. Choose less strenuous activities (like walking instead of running) so you don’t breathe as hard. Take more breaks.

Very Unhealthy (201-300) (Purple)

Health Alert: Everyone is at risk.

  • Sensitive groups: Avoid all physical activity outdoors. Reschedule or move activities indoors.
  • Everyone else: Avoid long or intense outdoor activities. Consider rescheduling or moving activities indoors.

Hazardous (301-500) (Maroon)

Health Warning: Everyone is at risk.

  • Everyone: Avoid all outdoor physical activities.
  • Sensitive groups: Keep activity levels low at home.

Fine Particles (PM 2.5) FAQs

Source: Excerpted from NYS DOH (revised June 2023). Full text is available on the source page.

Fine particulate matter (PM2.5 or PM2.5) is an air pollutant made up of tiny particles that presents a public health risk when levels in air are high. The New York State Departments of Health (DOH), Environmental Conservation (DEC), and Tompkins County Whole Health (TCWH) may issue a PM2.5 Health Advisory when outdoor air concentrations are expected to be unhealthy for sensitive groups.

What is Particulate Matter 2.5 (PM2.5)?

The term fine particles, or particulate matter 2.5 (PM2.5), refers to tiny particles or droplets in the air that are two and one half microns or less in width. The widths of the particles in the PM2.5 size range go from about thirty times smaller than that of a human hair to so small that several thousand of them could fit on the period at the end of this sentence.

How can PM2.5 affect my health?

Particles in the PM2.5 size range are able to travel deeply into the respiratory tract, reaching the lungs. Exposure to fine particles can cause short-term health effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath. Exposure to fine particles can affect heart and lung function worsening medical conditions such as heart disease and asthma, and increase the risk for heart attack.

Where does PM2.5 come from?

Outdoor sources of fine particles are primarily from vehicle exhausts and the burning of fuels such as wood (including wildfires), heating oil or coal. Fine particles also form from the reaction of gases or droplets in the atmosphere from sources such as power plants. Because fine particles can be carried long distances from their source, events such as wildfires or volcanic eruptions can raise fine particle concentrations hundreds of miles from the event.

Indoor sources of fine particles are tobacco smoke, cooking, burning candles or oil lamps, and operating fireplaces and fuel-burning space heaters (e.g., kerosene heaters).

Is there an air quality standard for PM2.5 in outdoor air?

Yes, the United States Environmental Protection Agency (EPA) established National Ambient Air Quality Standards for PM2.5 in 1997 and revised them in 2006 and 2012. National Ambient Air Standards are established to be protective of public health. The NYS Department of Environmental Conservation (DEC) provides PM2.5 monitoring data and PM2.5 forecasts on its AQI website. The DEC also maintains an Air Quality Hotline at 1-800-535-1345.

Are there ways to reduce my exposure to PM2.5?

People who may be especially sensitive to the effects of elevated levels of pollutants include the very young, older adults, and those with pre-existing respiratory problems such as asthma or heart disease.

Those who are especially sensitive to the effects of elevated levels of pollution should:

  • Avoid all physical activity outdoors.
  • Remain indoors and keep activity levels low.
  • Reschedule outdoor activities to a time when air quality is better or move activities indoors.

Everyone else should consider the following steps to reduce your exposure:

  • Avoid all physical activity outdoors.
  • Be active outdoors when air quality is better.

High quality masks, such as N95 and KN95 masks, can be worn outdoors to reduce the inhalation of fine particles from the air. Cloth masks and surgical masks are not effective at reducing inhalation of pollutants.

Additional Resources

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