Air Quality Guide for Ozone
Ground-level ozone is one of our nation's most common air pollutants. Use the chart below to help reduce your
exposure and protect your health. For your local air quality, visit www.airnow.gov
Air Quality
Index
Who Needs to
be Concerned?
What Should I Do?
Good
(0-50)
It's a great day to be active outside.
Moderate
(51-100)
Some people who may be un-
usually sensitive to ozone.
Unusually sensitive people: Consider reducing prolonged
or heavy outdoor exertion. Watch for symptoms such as
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)
Sensitive groups include
people with lung disease
such as asthma, older adults,
children and teenagers, and
people who are active out-
doors.
Sensitive groups: Reduce prolonged or heavy outdoor exer-
tion. Take more breaks, do less intense activities. Watch for
symptoms such as coughing or shortness of breath. Sched-
ule outdoor activities in the morning when ozone is lower.
People with asthma should follow their asthma action
plans and keep quick- relief medicine handy.
Unhealthy
(151-200)
Everyone
Sensitive groups: Avoid prolonged or heavy outdoor exer-
tion. Schedule outdoor activities in the morning when ozone
is lower. Consider moving activities indoors. People with
asthma, keep quick-relief medicine handy.
Everyone else: Reduce prolonged or heavy outdoor exer-
tion. Take more breaks, do less intense activities. Schedule
outdoor activities in the morning when ozone is lower.
Very Unhealthy
(201-300)
Everyone
Sensitive groups: Avoid all physical activity outdoors. Move
activities indoors or reschedule to a time when air quality
is better. People with asthma, keep quick-relief medicine
handy.
Everyone else: Avoid prolonged or heavy outdoor exertion.
Schedule outdoor activities in the morning when ozone is
lower. Consider moving activities indoors.
Hazardous
(301-500)
Everyone
Everyone: Avoid all physical activity outdoors.
Note: If you don't have an air conditioner, staying inside with the windows closed may be dangerous in extremely hot
weather. In these cases, seek alternative shelter.
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Key Facts to Know About Ozone:
Ozone in the air we breathe can cause serious health problems, including breathing difficulty, asthma attacks,
lung damage, and early death.
Ozone forms in the sun, usually on hot summer days. Ozone is worse in the afternoon and early evening, so plan
outdoor activities for the morning.
You can reduce your exposure to ozone and still get exercise! Use the Air Quality Index (AQI) at www.airnow.gov to
plan your activity.
What is ozone?
Ozone is a colorless gas that can be good or bad,
depending on where it is. Ozone in the stratosphere
is good because it shields the earth from the sun's
ultraviolet rays. Ozone at ground level, where we breathe,
is bad because it can harm human health.
Ozone forms when two types of pollutants (VOCs and
NOx) react in sunlight.These pollutants come from
sources such as vehicles, industries, power plants, and
products such as solvents and paints.
Why is ozone a problem?
Ozone can cause a number of health problems, including
coughing, breathing difficulty, and lung damage.
Exposure to ozone can make the lungs more susceptible
to infection, aggravate lung diseases, increase the
frequency of asthma attacks, and increase the risk of early
death from heart or lung disease.
Do I need to be concerned?
Even healthy adults can experience ozone's harmful
effects, but some people may be at greater risk. They
include:
People with lung disease such as asthma
Children, including teenagers, because their lungs
are still developing and they breathe more air per
pound of body weight than adults
• Older adults
People who are active outdoors, including outdoor
workers
United States
Environmental Protection
Agency
How can I protect myself?
Use the Air Quality Index (AQI) to plan outdoor activities.
To keep the AQI handy, sign up for EnviroFlash emails, get
the free AirNow app, or install the free widget on your
website. Find all of these tools at www.airnow.gov.
Stay healthy: exercise, eat a balanced diet, and keep
asthma under control with your asthma action plan.
When you see that the AQI is unhealthy, take simple steps
to reduce your exposure:
Choose a less-strenuous activity
Take more breaks during outdoor activity
Reschedule activities to the morning or to
another day
Move your activity inside where ozone levels are
usually lower
Can I help reduce ozone?
Yes! Here are a few tips.
Turn off lights you are not using
Drive less: carpool, use public transportation, bike
or walk
Keep your engine tuned, and don't let your
engine idle
When refueling: stop when the pump shuts off,
avoid spilling fuel, and tighten your gas cap
Inflate tires to the recommended pressure
Use low-VOC paint and cleaning products, and seal
and store them so they can't evaporate
Watch for Air Quality Action Days in your area
Office of Air Quality and Radiation
EPA-456/F-15-006
www.airnow.gov
August 2015
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