Published: 06:00, 04 February 2020
| Updated: 11:49, 05 February 2020
Air pollution in six areas of Kent exceeds toxic air guidelines set out by the World Health Organisation - putting the lives of nearly one million residents at risk.
Dartford, Medway, Gravesham, Maidstone, Tonbridge and Malling, and Swale have all made it onto a list of 30 council areas in the south east where people are being exposed to "dangerous levels of particles", known as PM2.5.
WHO guidelines say air pollution levels should not succeed 10 micrograms per metre.
Of the 30 councils highlighted, Dartford had the second highest level of toxic air recorded at 11.6, while Medway was fourth on the list with 11.5 and Gravesham fifth at 11.2.
Maidstone and Tonbridge and Malling both had 10.1 and Swale had 10.03.
Adding up the population in each area amounts to 936,000 people in the county at risk of health problems, such as blood clots that could lead to heart attacks, according to the British Heart Foundation.
Campaigners say the data published by the charity shows the urgent need for the government to set legally binding air pollution targets.
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Green Party campaigner Stuart Jeffery, who is based in Maidstone, said the figures were not a surprise given the growing evidence that pollution levels are one of the biggest problems facing the country.
"Tens of thousands of people are dying early each year and we have got 30 towns across the south east that are breaching World Health Organisation guidelines," he said.
"This report focuses on a single particulate matter 2.5, which is the smallest size of particles and they come from diesel engines, petrol engines so forth.
"They are very, very toxic, they can pass freely in and out of the bloodstream, they can go into the brain.
"They can basically affect any part any part of the body in terms of how they cause damage so they are particularly toxic, they're invisible and they don't smell at all so we don't know they're there."
It was earlier revealed people living in some of Kent's worst affected areas for pollution have an increased risk of death equivalent to smoking more than 140 cigarettes a year.
High pollution levels prompted residents to call for a high tech air and noise barrier to guard against toxic air coming from the Dartford Crossing.
Jacob West, BHF's director of healthcare innovation, said: "We can't see them, but every day, we all breathe in tiny toxic particles which damage our heart and circulatory health. They are an invisible killer.
"We must not become complacent and accept that dirty air is a part of normal life.
"Politicians have a unique opportunity to limit the damaging effects of pollution and improve the quality of our air, and they must seize it.
"Everyone can play their part in demanding a healthier environment for all.
"We are urging people to write to their MP to demand a change to the law.
"The more pressure we put on decision makers, the better our chances of cleaning up our air."
The UK currently subscribes to EU limits on levels of PM2.5, which are not as strict as those set out by the WHO, and progress towards reducing levels of major air pollutants has been mixed since the previous government's Clean Air Strategy was published in January 2019.
More than a year on, the BHF says that the nation's health cannot wait.
It wants the government to adopt the WHO's strict air pollution limits into UK law by 2030.
The Environment Bill, which returned to parliament last week, is a golden opportunity to set this in motion, the charity adds.
It promises the setting of legally binding air pollution targets, but some important commitments are missing, including pledges to adopt the stricter WHO guideline limits.
Jacob West, director of healthcare innovation at the BHF, said: "This government has a once-in-a-generation opportunity to take brave political action in cleaning up our toxic air.
"Tackling a public health emergency on this scale requires serious and sustained commitment.
"This could mean changes that might not be easy or convenient for organisations or individuals, but they will prove crucial to protecting people's health.
"You only have to look at past Clean Air Acts or more recently the smoking ban for examples of bold legislation that has improved the air we all breathe.
"The uncomfortable truth is that UK heart and circulatory deaths attributed to air pollution could exceed 160,000 over the next decade unless we take radical steps now."