Frequent Questions
This section provides information for counseling patients about ozone, asthma, and respiratory symptoms.
- Is ambient ozone exposure a risk factor for triggering asthma attacks in people with asthma?
- Should I recommend that my patients with asthma reduce their ozone exposure on days when air quality is unhealthy?
- How can an individual reduce his/her exposure to ozone?
- Should I advise my patients with asthma to alter medication usage on specific days or during longer periods when air quality is unhealthy?
- Are there any clinical effects of long-term exposure to ozone in healthy individuals?
- Should I advise my healthy patients without asthma to reduce exposure when air quality is unhealthy even if they do not experience any acute symptoms?
- What symptoms can short-term ozone exposure produce?
- How quickly should ozone-induced respiratory symptoms resolve in individuals without asthma?
- Where can my patients find information about the health effects of ozone exposure?
- How can a patient find out what times of day are typically more polluted for a given location?
- How can a patient find out when air quality is predicted to be unhealthy?
1. Is ambient
ozone exposure a risk factor for triggering asthma attacks in people with asthma?
Yes. Respiratory symptoms consistent with worsening asthma, medication
usage, and emergency room visits may be increased during or following
days when ozone levels are unhealthy. As with most triggers, some individuals
are more severely affected than others.
2. Should I recommend that my
patients with asthma reduce their ozone exposure on days when air quality
is unhealthy?
In general, yes. Those whose asthma is known to be more affected by
ozone exposure will benefit the most from exposure reductions, while
others may experience little or no benefit.
3. How
can an individual reduce his/her exposure to ozone?
Exposure can be reduced by reducing the time spent outdoors or reducing
the level or duration of outdoor activity during the times of day
that ozone levels tend to be highest in your area. These times of
poorest air quality are typically in the afternoon and early evening
for most locations, but this can vary by location.
4. Should I advise my patients with asthma
to alter medication usage on specific days or during longer
periods when air quality is unhealthy?
There is no information available to specifically address this question
for ozone exposure. Beta-agonist use will likely temporarily reduce
airway obstruction due to ozone exposure. However, it may also allow
continued activity, which may increase overall exposure. There are
no data available on the effects of inhaled steroid usage on asthma
status following ozone exposure.
5. Are
there any clinical effects of long-term exposure to ozone in healthy
individuals?
The answer to this is not known. Daily experimental ozone exposure
does affect the post-natal development of the respiratory tract in
nonhuman primates. Some epidemiological studies suggest that young
adults raised in areas of higher air pollution have a greater degree
of airway obstruction than similar adults raised in areas of lower
air pollution. Also, there is some evidence that long-term ozone exposure
may increase the risk of developing new asthma, particularly in males.
On the other hand, long-term ozone exposure does not appear to account
for a large part of the asthma or other respiratory disease in the
population living in some cities of the United States with high ozone
levels.
6. Should I advise my healthy
patients without asthma to reduce exposure when air quality is unhealthy even
if they do not experience any acute symptoms?
There are data suggesting that frequent exposure to ozone over many
years may increase the risk of developing respiratory disease; however,
these data are not conclusive. A simple approach would be to reduce
exposure when it can be done with little cost or inconvenience. Whether
a more vigorous approach to reducing such exposures is warranted or
whether exposure reduction is unnecessary remains to be clarified.
7. What
symptoms can short-term ozone exposure produce?
Cough, pain, burning or discomfort in the chest on taking a deep breath;
and shortness of breath may be experienced during and after exposure.
In addition individuals with asthma may experience symptoms of airway
obstruction such as wheezing and shortness of breath.
8. How quickly should ozone-induced
respiratory symptoms resolve in individuals without asthma?
They should begin to improve immediately upon cessation or reduction
of exposure and should have disappeared completely within 24 to 48
hours after the exposure ends.
9. Where can my patients find information about
the health effects of ozone exposure?
Information about the health effects of ozone may be found on the
AIRNow Web site in the Publications
section (http://airnow.gov/index.cfm?action=static.publications)
and the Your Health section (http://airnow.gov/index.cfm?action=static.health).
Copies of these publications may be ordered, free of charge, from
the National Service Center for Environmental Publications (NSCEP)
(http://www.epa.gov/ncepihom/)
Web site.
Your publication requests can also be mailed, called or faxed directly
to:
U.S. Environmental Protection Agency
National Center for Environmental Publications (NSCEP)
P.O. Box 42419
Cincinnati, OH 42419
1-800-490-9198
(513) 489-8695 (fax)
Please use the EPA Document Number, which is usually bolded or highlighted,
when ordering from NSCEP.
10. How can a patient find out
what times of day are typically more polluted for a given location?
On the Local Forecasts and Conditions page of the AIRNow Web site
(http://cfpub.epa.gov/airnow/index.cfm?action=airnow.local),
there is a clickable map of the United States. Clicking on a state
will lead to contact information for the state or local air quality
agency that issues air quality forecasts. These agencies will be able
to provide information about local diurnal ozone patterns.
11. How can a patient find out when air quality
is predicted to be unhealthy?
Air quality forecasts can be found with weather forecasts, either
in local newspapers, or on TV or the radio. Forecasts may also be
found on national news media such as The Weather Channel
and in USA Today. At about 4:15 PM Eastern time, next day
forecasts are available on the AIRNow Web site (http://www.airnow.gov).
![]() |
![]() |
|