The Chartered Society of Physiotherapy (CSP) claims that diesel engines are a serious threat to health across Britain because they are pumping out PM10 - a chemical that can cause breathing problems.
The CSP studied levels of PM10 at various monitoring points around the country and found that the pollutant consists of tiny solid or liquid particles of soot, dust, smoke, fumes and aerosols which could cause coughing, wheezing and shortness of breath.
World Health Organisation (WHO) experts believe there is no safe limit for exposure to PM10.
But the CSP said its analysis revealed there were high levels across Britain, with an average of 23.3 micrograms per cubic metre of air (micrograms/m3).