A link between heart disease and air pollution is being investigated in a new study published in the British Medical Journal. The amount of fumes in our urban cities could be causing a risk of heart attack, says the study.

Heart disease and air pollution have been studied before, according its writers but this is the first to investigate it on an hour by hour basis.

They quantified hourly risk of heart disease by comparing hospital data on myocardial infarction (heart attack) admissions with the hourly levels - PM10, ozone, CO, NO2, and SO2 - as recorded by monitoring stations across the UK's Air Quality and Data Statistics Database.

The rise and fall of UK's emissions appeared to raise the number of heart attack victims, according to the study published yesterday:

"This large-scale study shows conclusively that your risk of having a heart attack goes up temporarily, for around six hours, after breathing in higher levels of vehicle exhaust," said Dr Jeremy Pearson, of the British Heart Foundation, in a written statement. The British Heart Foundation who co-funded the study,

79,000 heart attacks occured in the course of the study, which took data from between 2003-2006. Their data further suggests that a period when traffic was highest, and levels of pollutants greatest caused numbers of heart attacks.