Scientists raise alarm after air pollution link to dementia found ‘likely’

Experts advising the UK government have urged tougher limits after a landmark report found polluted air causes damage to blood vessels in the brain.

Studies have contributed to a growing body of evidence that suggests a link.

Scientific advisers to the UK government have urged ministers to set tougher limits on air pollution after a landmark report found it probably contributes to causing dementia.

The Committee on the Medical Effects of Air Pollutants (Comeap), an independent panel of experts, reviewed 70 previous studies and concluded it was “likely that air pollution can contribute to a decline in mental ability and dementia in older people”.

The experts believe that polluted air causes damage to the blood vessels in the brain. In turn this can cause vascular dementia, which is estimated to affect about 150,000 people in Britain. A further 700,000 people have other forms of dementia, such as Alzheimer’s, where links to air pollution are less clear.

Scientists argue that inaction on air pollution now will cost people the ability to live independent, healthy lives in years to come.

Professor Frank Kelly, the Comeap chairman, said the government should “absolutely” adopt stricter targets on the most dangerous type of air pollution, known as PM2.5, based on guidance by the World Health Organisation.

PM2.5 is formed of airborne particles with a diameter less than 2.5 micrometres, about a twentieth of the breadth of a human hair. The WHO has called for an average annual exposure not above 5 micrograms per cubic metre, but the government has proposed 10 micrograms per cubic metre for England by 2040. The Environment Act requires a target to be set by the end of October.

Professor Nick Fox, director of the Dementia Research Centre at UCL and one of the authors of the new report, said: “Inaction now will cost people the ability to live independent, healthy lives in years to come … The evidence is very strong that exposure to air pollutants is likely to increase your risk of dementia, possibly decades later.”

The Clean Air for All campaign, launched by The Times in 2019, has called for limits based on WHO recommendations. At present, regulations set a limit five times higher, at 25 micrograms.

Sir Andrew Goddard, president of the Royal College of Physicians, said that the type of studies on which the new report is based cannot prove a causative relationship between air pollution and dementia. But he added that they contributed to a growing body of evidence suggesting a link.

Steps that would reduce airborne particles with a diameter less than 2.5 micrometres include the elimination of fossil-fuel power stations. Picture: Getty Images

He has called for a PM2.5 target of 10 micrograms per cubic metre to be met by 2030, and for 5 micrograms by 2040. “It’s based on the government’s own projection that they could probably get down to 11 by 2030,” Goddard said.

Eight medical royal colleges, including the Royal College of Physicians, said last month that limits proposed by ministers would “fall far short of the level required to improve health and save lives”.

Steps that could reduce PM2.5 would include eliminating fossil-fuel power stations, reducing wood burning in homes, and removing old vehicles.

Professor Alastair Lewis, of the University of York, said that meeting WHO targets would be challenging, especially in the southeast of England, which is affected by air pollution from the Continent.

He added: “The report adds more evidence on the wide range of effects that air pollution has on public health … It’s something that accumulates inside us all over the long term.”

The Department for Environment, Food & Rural Affairs said: “Air pollution at a national level continues to reduce significantly, with nitrogen oxide levels down by 44 per cent and PM2.5 down 18 per cent since 2010, although we recognise we need to go further.”

It has estimated that achieving the targets proposed by ministers would result in up to 214,000 fewer cases of cardiovascular disease, 56,000 fewer strokes, 70,000 fewer cases of asthma and 23,000 fewer cases of lung cancer over 18 years.

The Times