Ozone monitoring in York allowed sufferers of respiratory problems to be warned quickly of risks after the city recorded high levels, councillors will be told this week.

Asthmatics were told to avoid strenuous exercise and carry inhalers as an August heatwave put York on pollution alert.

The monitoring system operating in Dunnington meant high ozone readings were registered immediately, letting council officers publicise dangers. Asthmatics and others with breathing problems could also predict how long precautions against health threats would need to be taken.

The council's air quality strategy officer, Elizabeth Ingle, will tell members: "One of the key points to be raised from the air pollution incident was that once the episode had started officers were for the first time able to accurately predict high levels of pollution on the following days.

"This allowed enough time for those who are most vulnerable to the effects of air pollution to be warned in advance and gave them time to take any necessary precautions."

Ozone is created by the action of sunlight on pollutants in the atmosphere.

It can cause problems for people with respiratory problems such as asthma, emphysema and chronic bronchitis.

Monitoring is not compulsory, with many local authorities not recording ozone levels in the same way as York.

Levels recorded in early August were similar to those in Hull and Leeds, although different weather conditions experienced throughout the region, including thunderstorms and winds created differences.

The findings will be reported to members of the environmental services committee on Wednesday.

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