Backyard bonfires burning off wood and uncollected waste have seen a spike in air pollution in south-east London, bucking trends seen in cities across the country.

Across the vast majority of the UK air quality has already started to improve following Boris Johnson’s announcement of a nation-wide lockdown on Monday.

However, in Bromley, air quality monitors have captured rapid jumps in levels of PM2.5 – tiny particles of airborne matter ranging from pollen and dust to man-made pollution – since Monday.

The culprit is believed to be residents in the outer London district conducting backyard fires – with reports the increase in bonfires has come partly from residents burning off recyclable waste as collection services are impacted by a lack of staff due to to the virus.

On Monday, levels of PM2.5 were 9.5 micrograms per metre cubed, according to an Orpington air quality monitoring station.

This has steadily increased through the week – up to 17 on Wednesday, 22 on Thursday, and 24.8 on Friday.

The European Union’s recommended threshold for levels of PM2.5 is 20 measured annually, while the World Health Organisation’s is just 10.  

While the increased levels are thought to have been purely driven by bonfires, additional pollution coming into the south-east corner of the country from across the channel – combined with pollutants not being dispersed in the calm, still air – contributed to the jumps.

The issue has prompted Bromley Town ward’s Tory councillors to appeal on Friday for residents to resist lighting backyard bonfires.

It comes after the authority suspended home recycling collection, as staff absences start to bite the service. 

In a statement put out by Bromley Town’s Conservative councillors, they confirmed up to 35 per cent of staff making up the authority’s bin collection workforce are self-isolating because they either have coronavirus symptoms or are living with vulnerable people.

“Please don’t start a bonfire, nuisance bonfires remain banned,” the ward members added in a post on their ward Facebook page.

According to independent air monitor Tim Webb, the anti-social impact of bonfires and the associated increase in pollution is among the most pressing issue with the development.

“The problem with bonfires is you’re talking about all types of pollutants going in the air from the combustion process,” he said.

“Once pollution rates go up, they take a very long time to go back down.”

“The problem is this is a source of pollution and these particles don’t stay trapped in your garden, they can travel – if your neighbours have got respiratory conditions, something like this could trigger an asthma attack.”