Health impacts (2024)

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Page Last modified 23 Nov 2023

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Up to 30% of Europe's urban population is exposed to ozoneconcentrations above the threshold levels set by the EU to protecthealth.

The main health effects ofshort-term (a few hours) exposure to ozone include irritation of throatand eyes, coughing, wheezing, inflammation of lungs and difficulties inbreathing.

These effects may occur in people with respiratory diseases,children and the elderly when the ozone concentration reaches a levelhigher than 180 µg/m³ (EU information threshold).Above 240 µg/m³ (EU alert threshold), health effectswill be increasingly severe and may be experienced by most individuals.See also: How can I protect my health?

Ozone at high concentrations leads to health problems, because itattacks the lining of our lungs. This can cause lung inflammation(irritation) even after only a few hours of exposure. Our airwaysrespond to the exposure by covering the affected areas with fluid andby contracting the lung muscles. Breathing becomes more difficult andlung capacity decreases.

The lungs will usually recover within a few days after exposure toelevated concentrations of ozone. However, if ozone exposure isexperienced over a longer period of time or on a number of repeatedoccasions within a year, chronic damage to lung tissue may occur. Thismeans that the lung function may be affected and the lining may losesome of its ability to serve as a protective barrier against microbes,harmful chemicals and allergens.

Also, recent research studies suggest that long-term exposure toozone may be associated with lung cancer. This possibility is expectedto be further explored.

Table. Health effects associated with exposureto ozone. (Adapted from WHO2004)

Asthma

Ozone can aggravate asthma and may also worsen other respiratoryillnesses such as pneumonia and bronchitis. Evidence shows that whenozone concentrations are high, asthmatics have more attacks than usualand need more medication.

There is little evidence, however, to support the suggestion thatthe long-term upward trend in ozone pollution is the reason for thegrowing number of asthmatics. Asthma is now the most common respiratorydisease among western European children, afflicting 7 % of childrenaged between 4 and 10.

Children’s health

Children are particularly sensitive to air pollution, because theybreathe more air per kilogram of body weight and have smaller lungsthan adults. Also, children – especially newborn babies – arevulnerable because their metabolism and lung defence mechanisms are notfully developed.

Evidence indicates that long-term ozone exposure reduces thedevelopment of the lung function in children. This may contribute to ashorter life expectancy, because decreased lung function is one of thestrongest predictors of increased mortality in adults.

There is also evidence that high exposure to ozone increases theoccurrence of lung infections (e.g. pneumonia and coughing) inchildren.

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