Southeast London is among the most polluted areas in the UK, with residents exposed to levels above the safe limit recommended by the World Health Organisation (WHO), figures reveal.

Health campaigners say "toxic" air quality in the UK is a national emergency and the Government must impose stricter limits on fine particles in the air (PM2.5), which come mainly from the burning of oil, gas and diesel.

The calls have been heightened after a coroner, while ruling that air pollution was a cause of the death nine-year-old Ella Adoo-Kissi-Debrah in Lewisham, said there was "no safe level" of PM2.5, adding WHO guidelines should be seen "as minimum requirements".

Figures show that both Lewisham and Greenwich topped the table according to the latest set of projections from 2019.

Data from the Department for Environment Food and Rural Affairs show that in both boroughs, the concentration of PM2.5 pollution particles in was 11.9 micrograms per cubic metre in 2019 – below the UK limit of 25, but above the WHO guideline limit of 10.

Read more: Lewisham council statement after Ella Adoo-Kissi-Debrah inquest verdict

Though for both boroughs, this represented a decrease from 12.4 micrograms of PM2.5 pollution particles recorded in 2018.

Dartford in north Kent followed close behind, with the average concentration of PM2.5 particles recorded as 11.7 micrograms per cubic metre in 2019 – a decrease from 12.1 micrograms in 2018.

Bexley recorded an average PM2.5 concentration of 11.4 micrograms per cubic metre in 2019, down from 11.8 micrograms in 2018.

A coroner recently ruled that air pollution contributed to the death of Lewisham girl, Ella Adoo-Kissi-Debrah

A coroner recently ruled that air pollution contributed to the death of Lewisham girl, Ella Adoo-Kissi-Debrah

According to the figures, Bromley ranked as the cleanest air in southeast London, with an average PM2.5 particle concentration of 10.6 micrograms, down from 11 micrograms in 2018. Though despite being having the cleanest recorded air in the region – it still measures above the WHO guideline limit of 10 micrograms.

PM2.5 are tiny particles, measuring about 3% of the diameter of a human air, which can lodge in the lungs and even pass into bloodstream, potentially causing damage to blood vessels and organs.

They come mostly from traffic fumes, but also through industrial emissions, wood burners and livestock manure. A small proportion come from natural sources in the form of dust or sea salt particles.

Read more: Ella Kissi-Debrah - Lewisham death prompts air quality calls

Levels of the PM2.5 particles in England have fallen since 2011, when national records began, from 12.1 micrograms per cubic metre to 9.6 in 2019.

Defra’s readings for PM2.5 are calculated using air quality measurements along with numbers and locations of people in each local authority to provide average annual levels of exposure.

The British Heart Foundation, which is campaigning for stricter limits on PM2.5 as part of the Government's Environment Bill which returns to Parliament this year, says the country faces “a public health emergency”.

John Maingay, director of policy and influencing at the charity, said: "Our toxic air is a public health emergency, and now is the time to take robust action to support everyone’s health as we look to recover from the pandemic."

He added: “We are pleased that the Environment Bill, which will set more stringent air quality limits, will soon be returning to complete its passage through Parliament.

"However, this must go further and ensure WHO limits are adopted into law, and met by 2030.

“Stricter, health-based air quality guidelines are urgently needed to protect the health of the nation and clean up toxic air for good.”