Study finds bonfires emit more PM10s than engines

An 18-month study on a regeneration site in London for the Greater London Authority (GLA) seen by Contract Journal shows that bonfires and barbecues put more PM10s (the particulates limited by legislation) into the air than engines in plant machinery.

Pollution levels on Bonfire night hit six times the permitted daily average readings - a level not equalled during the demolition of a building adjacent to the monitoring station. Garden bonfires and barbecues produced emissions spikes of between two and six times the daily limit, which is thousands of times lower than cigarette smoke.

A diesel generator 5m from the measuring station did exceed the daily average limit (by 50%) but this level did not extend beyond the site boundary. And despite the visit of up to 70 trucks a day, the limit was never exceeded outside the site except in times of high ambient pollution levels.

"This shows there is no real correlation between diesel engines running on construction sites and the general air quality," said Colin Wood, chief executive of the Construction Plant-hire Association. "To ask plant hirers and contractors to spend millions of pounds retrofitting Diesel Particulate Filters to thousands of machines on the basis of this research is pure nonsense," added Wood.

The study attributes a rise in ultra-fine particulates (PM1 and below) down wind of the site to diesel emissions, but trucks producing similar emissions are not charged to enter the London Low Emission Zone. "To penalise plant on this basis is pure hypocrisy," said Wood.

He favours the use of rebated low sulphur diesel, similar to that in on-road trucks, for plant operating within the M25 (which will cut PM10 emissions by around 12.5%) and will ask the GLA to re-examine cheaper and simpler methods of reducing pollution.