Asthma attacks are three times as common as previously thought, according to new figures which have sparked warnings about the impact of air pollution.

Data from the charity Asthma UK suggests that every three seconds somebody in the UK has an attack.

Its figures suggest 10 million such episodes annually, when previous figures suggest around three million attacks annually.

The charity surveyed more than 10,000 people with asthma, who reported having an attack on average twice a year.

Its experts said some of the rise could be attributed to the fact that previous attempts to estimate the total number of attacks only measured the amount of medication used, missing cases where patients struggled without an inhaler.

But they also raised concerns that growing numbers of children and adults were suffering from breathing results as a result of air pollution, and of poor NHS management of their condition.

Asthma attacks can be life-threatening, with three people on average dying every day from an attack.

The condition affects the airways, narrowing them and making it harder to breathe.

Triggers can include cold air, coughs and colds, and grass pollen.

Dr Andy Whittamore, clinical lead at Asthma UK, said: "It is shocking to think that every three seconds in the UK someone could be having an asthma attack, a terrifying experience than can cause distress and in some cases prove fatal.