Air pollution: All London homes exceed toxic pollution limits, data reveals
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But the full scale of the problem has remained unclear given the lack of detailed data.
Now researchers at the Central Office of Public Interest (COPI) have found it could be much worse than previously thought.
Scientists launched a website called addresspollution.org to monitor local pollutants levels.
The national pollution checker was created using data from Imperial College London, collected from 20,000 monitoring sites in over 320 UK council areas.
It shows the levels of three toxic pollutants - PM2.5, PM10 and NO2, at any UK address and gives them a percentage ranking, from zero to 100.
And the tool found that all 3,590,253 addresses across the city’s 33 boroughs exceed WHO limits for all three key pollutants.
On average, the five most polluted boroughs are the City of London, Westminster, Kensington and Chelsea, Hammersmith and Fulham and Islington, while the five least polluted on average are Havering, Bexley, Sutton, Croydon and Bromley.
However, Enfield, Southwark, Ealing, Brent and Lambeth are the five boroughs with the highest number of properties which are above the 80th percentile for air pollution.
While the five lowest for this marker are Kensington and Chelsea, Kingston-upon-Thames, Sutton, Bromley and the City of London.
Campaigner Rosamund Kissi-Debrah, whose nine-year-old daughter, Ella, died of a fatal asthma attack brought on by air pollution in 2013 said: "This data shows yet again that the government is failing the British public.
"Now people can really see the filthy air they’re breathing at their home, school or work address, and it is no wonder that the NHS waiting lists are ever growing.
"Everyone needs to know what they’re breathing, and now with this new public service they can."
COPI founder Humphrey Milles, who created the website, said: "Air pollution affects all of us.
"It’s a group one cause of cancer, just like asbestos.
"With this new accurate data now publicly available, it would be shameful for the property industry to not start acting transparently.
"Lives depend on it."
Professor Sir Stephen Holgate, air quality expert at the Royal College of Physicians, said: "Air pollution is an invisible killer - as you can’t see it it’s easy for people to forget and ignore.
"It’s essential that the public are given air pollution data for where they are thinking of buying or renting.
He added: “In many cases like that of little Ella, it can be a matter of life or death."
The researchers looked at pollution levels recorded in every major town and city across the UK to see how urban areas fared and identify pollution hotspots.
They found 21.5 million UK addresses breach the World Health Organisation limits of three toxic pollutants.
Nearly all homes - 97 per cent, were over at least one of the organisation’s toxic air limits.
While cities suffer most, addresses in greener parts of the country like Kent, Bath and some coastal towns have some of the worst levels.
For example, Buckingham Palace in central London falls within the 98th national percentile, with some of the highest air pollution levels in the UK.
Balmoral Castle on the other hand, falls into the lowest percentile - zero, with some of the cleanest air anyone can expect to breathe, the researchers say.
Health implications for living at a given address are also provided on the website depending on whether it receives a low, medium, significant, high or very high rating.
The researchers are pushing for air pollution rating to be published by estate agents, property websites, surveyors and conveyancers.
Mr Milles said: "Everyone has a right to know what they’re breathing before they buy or rent and of course, we have our own part to play in this too.
"Air pollution isn’t insurmountable and we can all do something about it.”
To find out more or check your address, visit: https://addresspollution.org/