Weather experts have warned against a "deadly pollen bomb" that is due to hit Northern Ireland within the next 24 hours.
Widespread moderate air pollution is forecast for Wednesday right across Northern Ireland and it is expected to last through to Easter Sunday.
There is a potential for isolated areas of high air pollution to occur during this period.
These levels are occurring as a result of prevailing weather conditions, with light winds bringing air pollution from the continent and adding to the build-up of locally generated air pollutants.
During periods of high air pollution the symptoms of people with lung or heart disease may worsen.
Healthy people are unlikely to experience any ill effects.
“A deadly pollen bomb is due to hit this week, putting people with asthma at risk of a potentially life-threatening asthma attack," said Sonia Munde, head of Asthma U.K.
“Trees have been releasing their pollen for several weeks, but the warm spring weather is going to make these pollen levels spike.”
Hourly updates on levels of particulate matter (PM10 and PM2.5), sulphur dioxide, nitrogen dioxide, ozone and carbon monoxide are available on the Department’s website: www.airqualityni.co.uk and the Department’s freephone helpline: 0800 556 677, which also offers health advice to those who may be particularly sensitive to air pollution.
The following advice on health applies when air pollution is 'high' or 'very high':
While most people will not be affected by short term peaks in air pollution, some people - particularly vulnerable groups such as those with existing heart or lung conditions - may experience increased symptoms.
If you think you may be affected by air pollution levels, you should consider modifying your treatment as you usually do when symptoms increase and, consult your doctor if this is not effective.
You may also wish to reduce the time you spend outdoors or avoid busy, congested streets.
If you have noticed in the past that your breathing is affected during cold, calm conditions or on hot, sunny days, you should avoid strenuous outdoor activity on those days and ensure that you have access to your usual medication, such as asthma inhalers.
Children with asthma should be able to take part in games in the usual way, although they may need to increase their use of reliever medicines before participating.
There is no need for them to stay away from school.
If you suffer from a heart condition and notice a change in your symptoms, you should seek medical advice as you normally would.
(Source: The Department of Agriculture, Environment and Rural Affairs)