Ozone and Health

Ground-level ozone (ozone) is the main ingredient in smog. Breathing in unhealthy levels of ozone can increase the risk of health problems like coughing, breathing difficulty, and lung damage. Unhealthy levels can also reduce visibility and cause the air to appear hazy.

Ozone pollution forms in sunlight, usually on hot summer days, when volatile organic compounds and nitrogen oxides react in sunlight. These pollutants come from sources such as vehicles, industries, power plants, gasoline equipment, and products such as solvents and paints.

When Outdoor Air is Unhealthy

  • Spend more time indoors. This is especially important for at-risk groups (“sensitive groups”) such as children and teenagers, older adults, people with lung disease like asthma, and those who exercise or work outdoors.
  • When it's too hot inside, cool off with air conditioning. Find a place to get cool.
  • People who must work or exercise outdoors should do so in the morning when levels are usually lower and take frequent breaks.
  • Schools, child and adult care facilities, employers and activities programs should plan for more indoor activities or schedule outdoor activities in the morning when ozone levels are lower.
  • People with health symptoms should contact their health care provider.
  • Get the latest air quality conditions by visiting DEC's air quality forecast website or airnow.gov.

Follow Air Quality Alerts

New York State alerts the public when ozone levels are expected to be unhealthy. An Air Quality Alert is issued the day before or the same day for the region of the state that is affected. These alerts are often broadcast on the news or weather stations.

When it's hot, try to spend at least a few hours in air conditioning. Find a place to get cool. People with respiratory conditions should follow their health care provider's treatment plan and keep quick-relief medicine handy.

AQI Basics for Ozone Pollution
Air Quality Index Who is at risk? What to do?
Green: 0 to 50 Good Air quality is good. It's a great day to be outside.
Yellow: 51 to 100 Moderate People unusually sensitive to air pollution. Air quality is acceptable. Consider making outdoor activities shorter and less intense. If you are coughing or have shortness of breath take it easier.
Everyone else: It's a good day to be active outside.
Orange: 101 to 150 Unhealthy for Sensitive Groups

Sensitive (at-risk) group: people with lung disease such as asthma, older adults, children and teenagers, and people who work or are active outdoors.

Sensitive group: Make outdoor activities shorter and less intense. Take more breaks. Watch for symptoms such as coughing or shortness of breath. Plan outdoor activities in the morning when ozone is lower.
Everyone else: Consider making outdoor activities shorter and less intense.

 
Red: 151 to 200 Unhealthy Everyone

Sensitive group: Avoid long or intense outdoor activities. Schedule outdoor activities in the morning when ozone is likely to be lower.
Everyone else: Reduce long or intense outdoor activity. Take more breaks, do less intense activities. Schedule outdoor activities in the morning when ozone is lower.
Purple: 201 to 300 Very Unhealthy Everyone: Health Alert Sensitive groups: Avoid all physical activity outdoors. Reschedule or move activities indoors.
Everyone else: Avoid long or intense outdoor activities. Plan outdoor activities in the morning when ozone is lower.
Maroon: 301-500 Hazardous Everyone: Health Warning Everyone: Avoid all outdoor physical activities.
Sensitive groups: Avoid physical activities outdoors .

When it's hot, try to spend at least a few hours in air conditioning. Find a place to get cool. People with respiratory condition should follow their health care provider's treatment plan and keep quick-relief medicine handy.

Recommendations for Workers

  • Long schedules and the physical demands of outdoor work can affect health when air quality is unhealthy. If you must be outdoors, try to adjust schedules so that work or exercise take place in the morning when ozone levels are usually lower.
  • Take frequent breaks and talk to your employer about adjusting your work until air quality improves. Follow advice from NIOSH.

Recommendations for Schools and Child Care Providers

  • Continue to monitor air quality at DEC's air quality forecast website or airnow.gov.
  • Consider implementing an Air Quality Flag Program where your organization raises a flag for the day when the air is unhealthy. On these days you can use this information to adjust outdoor activities.
  • New York State recommends that schools and child care providers suspend outdoor activities and field trips when air quality is unhealthy.
  • When air quality is good, you can resume normal activities.

More About Health Risks

Ozone levels are most likely to be unhealthy in the afternoon through early evening on hot, sunny days, especially during episodes of stagnant air. Daily ozone levels can be influenced by local weather events, regional weather patterns and the presence of chemicals in the air that react to form ozone.

The New York State Departments of Health and Environmental Conservation (DEC) alert the public when ozone levels in outdoor air are expected to be unhealthy. An air quality health advisory is issued for the next day or on the same day for a specific region when ozone concentrations at one or more monitoring stations in that region are predicted to be elevated. Each summer weekday morning, DEC staff review morning ozone monitoring data and weather conditions to determine if an air quality health advisory is warranted . There could be a few days each year when the monitoring data, meteorology and computer modeling fail to correctly predict the need for an advisory.

Breathing in unhealthy levels of ozone can cause eye, nose, and throat irritation, respiratory symptoms and a decrease in lung function. Symptoms can occur in healthy people while exercising or doing strenuous work when ozone levels are high. People with lung diseases such as asthma, older adults, children and teenagers are also at risk when ozone levels are high. Respiratory symptoms include shortness of breath, chest pain and coughing, and may occur in both adults and children. In community studies, days with high, outdoor ozone levels tend to have higher hospitalizations for respiratory conditions and increased daily mortality rates. More limited evidence suggests that short-term exposure to high ozone levels might also aggravate cardiac symptoms in people with pre-existing heart disease or high blood pressure.

Health studies with laboratory animals suggest that long-term exposure to high ozone levels may be associated with permanent changes in airway structure and reduced lung function. However, current information about permanent health effects from long-term exposure in humans is inconclusive. Some human studies reported evidence of permanently reduced lung function development associated with long-term childhood exposure to elevated ozone levels, while others have not. An increased risk of developing asthma was found among children who likely experienced long-term elevated ozone exposure because they participated in athletic programs in areas with high average ozone levels.

The United States Environmental Protection Agency (EPA) established the National Ambient Air Quality Standard for ozone. The standard is currently set at 0.070 parts per million averaged over 8 hours.

More Information

Air Quality

Related Information

Questions