A health warning has been issued in Brighton and Hove today after air pollution levels soared.

The safety limit for ozone, known as summer smog, has been passed every day since the heatwave began nine days ago.

Background pollution was more than double the safety level on Saturday and Monday and continued high yesterday.

Levels are expected to remain high until fresher weather arrives.

Ozone, caused when vehicle emissions react with sunlight on windless days, combine with other chemicals and can trigger coughing fits, shortness of breath and sore throats.

People with respiratory conditions were advised to keep inhalers close to hand and consult a doctor if symptoms persist.

Sotiris Vardoulakis, development officer of the Sussex Air Quality Steering Group, said: "We have a relatively high ozone concentration."

Ozone levels are typically low at night and build up during the day.

Rural and suburban areas tend to have higher concentrations than city centres.

Background levels at the Foredown monitoring station, Hove, have passed 120 parts per billion twice during the heatwave.

The Government's objective to protect health is 50 parts per billion.

Similar elevated levels have been recorded at rural monitoring stations across Sussex.

Roadside measurements in Brighton and Hove have been lower but still passed the 50 parts per billion mark on each day of the heatwave.

Sussex is noted for high levels of summer smog because of air pollution in South-East England and its proximity to continental Europe.

The amount of ozone has passed health limits at 76 of 80 stations in the Government's national air quality monitoring network.