A COCKTAIL of pollutants including dust from the Sahara Desert contributed poor air quality in Bradford and across England yesterday.

According to data by Defra's UK Air Information Resource, pollution levels were "very high" (on a 10 out of 10 scale for air quality) in the Yorkshire and Humber at 10am Thursday, but the levels dropped to "high" during the day (eight out of 10).

Due to the poor air quality, the general population was advised to reduce physical exertion.

Pollution levels measured higher in coastal regions and London while at 11.30am Thursday Bradford levels were only moderate, but local measurements at 9am were "poor".

"This pollution has been in the forecast and measurements for the last two or three days," said Jim McQuaid, pollution scientist at Leeds University who works on the Born in Bradford Bib Breathes project. "The nice weather and low winds are not helping us.

"The air is stagnant and just sits there and festers. The air is slowly drifting from Europe and southern England.

"A lot of pollution is driven by the weather and can be affected by changes in wind speed or direction.

"Last week we had quite a major Sahara dust episode and this kind of pollution can travel a long way "There is particulate material from the continent that has spent quite a long time in the atmosphere.

"It mixes with exhaust from cars and lorries, road dust and smoke from burning such as moorland fires.

"It's a cocktail and is quite a complex mixture, said Mr McQuaid: "This can be quite serious if you have asthma or breathing difficulties."

As part of the Bib Breathes project, eight sensors have been installed at schools around Bradford, including one at Beckfoot Allerton Primary School which had the highest measurements yesterday.

The sensor noted the air quality has been poor throughout the day, but at 9am this morning it was "very poor".

Mr McQuaid said: "This is why there are arguments for a Clean Air Zone (CAZ) because the quality of air impacts the lives of schoolchildren, whose growing lungs are most vulnerable to air pollution.

"The air quality is meant to be bad until Sunday, added Mr McQuaid. "Currently West Yorkshire is forecast to get hit with 9/10 on Sunday, but if the weather changes dramatically, the winds pick or it rains then this episode might be over quite quickly."