A POTENTIALLY dangerous cloud of air pollution is expected to blow across Britain today, and has resulted in parts of north Hampshire being issued with a health alert.

The Department for Environment, Food and Rural Affairs (Defra) has placed a moderate warning on both Whitchurch and Overton, while Basingstoke is within the low category of the air pollution index band.

Experts said the smog could cause fatal asthma attacks and have warned the elderly and those with health problems to be cautious.

Defra said the air pollution is blowing in from Europe and mixing with home-grown smog to create the problem.

Officials warned this could trigger health difficulties for those with respiratory illnesses and the elderly, although it does not pose a health threat for the general population.

A Defra spokeswoman said: “Winds bringing in pollution from the continent, combined with locally generated pollution and still weather conditions has led to some high pollution measurements across the UK.

“Levels are expected to return to low by Friday.”

Basingstoke is on level three out of 10 on the air pollution index band, whilst Whitchurch and Overton are at four.

A moderate warning means that adults and children with lung problems, and adults with heart problems, who experience symptoms, should consider reducing strenuous physical activity, particularly outdoors.

Kay Boycott, chief executive of Asthma UK, said: “Two thirds of people with asthma find that air pollution makes their asthma worse, putting them at an increased risk of a potentially fatal asthma attack.

“When air pollution is high it’s vital people with respiratory conditions including asthma check air pollution forecasts, carry their reliever inhaler with them at all times, and ensure that they are taking their preventer inhaler every day because this will help build resilience to asthma triggers like air pollution.”