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Small amounts of air pollution can cause fatal heart attacks, strokes

The findings were based on an analysis of 3.7 million adults in California.

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By Mark Waghorn via SWNS

Even small amounts of air pollution cause potentially fatal heart attacks and strokes, according to new research.

A study found people exposed to levels below half those recommended in the UK were more likely to die from cardiovascular disease.

The findings suggest current regulatory standards are not sufficiently protective, say scientists.

They were based on an analysis of 3.7 million adults in California - one of the biggest of its kind.

Lead author Dr. Stacey Alexeeff, of Kaiser Permanente Division of Research in Oakland, Calif., said: "We found people exposed to fine particulate air pollution have an increased risk of experiencing a heart attack or dying from coronary heart disease - even when those exposure levels are at or below our current US air quality standards.

"Our work has the potential to play an important role in ongoing national conversations led by the Environmental Protection Agency on whether - and how much - to tighten air quality standards to protect the public from pollution's effects."

The U.S. team looked at PM2.5s - the leading environmental risk factor for disease. Less than a 50th the width of a human hair, they get into the blood through the lungs making it more sticky - triggering inflammation.

They come from diesel fumes, wood smoke, brake pads, tyres and road dust. The current legal limit in the UK is twice the WHO (World Health Organization) recommendation, at 20 micrograms per cubic meter.

The study found exposure at a concentration between 12.0 and 13.9 micrograms per cubic meter was associated with a 10 and 16 percent increased risk of a heart attack and dying from heart or cardiovascular disease, respectively, compared to concentrations less than eight.

In the U.S., the Environmental Protection Agency's current annual regulatory standard for PM2.5s is an average of 12 over a year.

In January, it announced a proposal to reduce the acceptable level to between nine and 10 on the grounds public health was not being adequately protected.

Participants had lived in the state for at least a year. They were tracked for up to a decade.

Heart attack and heart disease mortality rates also rose six and seven percent, respectively, among those exposed to moderate concentrations of 10 to 11.9 micrograms per cubic metre.

It suggests there would be health benefits if the new standard were 10 micrograms per cubic metre or less.

Increased risk of heart attacks persisted even at concentrations of eight to 9.9 - indicating the US would see fewer if the new standard were reduced to eight.

The study also linked deprivation to pollution exposure and the risk of cardiovascular disease.

Co-author Dr. Stephen Van Den Eeden said: "We found strong evidence that neighborhood matters when it comes to exposures to this type of air pollution.

"The strongest association between exposure to air pollution and risk of cardiovascular events in our study was seen in people who live in low socioeconomic areas, where there is often more industry, busier streets and more highways."

It is hoped the findings in JAMA Network Open will influence ongoing policy discussions.

Dr. Alexeef said: "Our study clearly adds to the evidence the current regulatory standards are not sufficient to protect the public.

"Our findings support the EPA's analysis that lowering the standard to at least 10 micrograms per cubic meter is needed to protect the public.

"Our findings also suggest that lowering the standard to eight micrograms per cubic meter may be needed to reduce the risk of heart attacks."

Senior author Dr. Stephen Sidney described the study as one of the largest to look at the impact of air pollution on heart disease.

He added: "Importantly, Kaiser Permanente's electronic health records made it possible for us to account for other factors that might increase a person's risk of having a heart attack or developing cardiovascular disease, such as smoking status, body mass index, or having other illnesses, such as diabetes.

"This allows us to be confident in our conclusion that fine particle air pollution has adverse associations with cardiovascular health."

Heart disease develops when cholesterol builds up inside arteries, preventing the organ getting the blood and oxygen it needs.

Cardiovascular disease covers all conditions that can affect the heart and blood vessels such as heart failure, stroke and peripheral artery disease.

A previous study of 4,000 Britons suggested low levels of air pollution causes changes to the heart similar to those in the early stages of heart failure.

Those who lived by loud, busy roads had larger hearts on average than peers in less polluted areas - despite air quality being within UK guidelines.

For every extra one microgram per cubic meter of PM2.5 - small particles of air pollution - and for every 10 extra micrograms per cubic meter of nitrogen dioxide, the heart enlarged by about one percent.

The changes were comparable to being consistently inactive or having elevated blood pressure, said the Queen Mary University of London team.

Air pollution kills an estimated 1.8 million people across the world each year. It is also behind nearly two million cases of childhood asthma.

In 2013, PM2.5s were classed as a carcinogen by the International Agency for Research on Cancer. They were also implicated in increasing the risk of Covid.

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