Air pollution causes dementia: UK Government advisers confirm link for first time

The UK government has acknowledged for the first time that air pollution is causing an increase in dementia.

Toxic airborne particles from cars and fossil fuels have long been associated with rapidly increasing rates of disease in the UK and developed world.

Now, a large-scale study on behalf of the UK Health Safety Agency has confirmed the link after analyzing dozens of human studies.

The researchers concluded that “air pollution may contribute to a reduction in mental abilities and dementia in the elderly.”

They believe the primary way this happens is through tiny toxic particles that enter the bloodstream after being inhaled into the lungs.

The contaminants then irritate the blood vessels and cut off circulation to the brain. This can eventually lead to vascular dementia.

In rare cases, it is also possible for very small particles of air pollution to cross the blood-brain barrier and directly damage neurons.

However, the report noted that this does not appear to be an important mechanism for air pollution in the UK at this time.

The chart above shows the current legal limit for air pollution in the UK (far left) and the UK plans to halve it to 10 mcg/m3 by 2040 (left). However, this is still above the 5 mcg/m3 level recommended by the World Health Organization (WHO).

Although a link has been established, there is still not enough evidence to say how many cases of dementia are due to air pollution.

Some studies have suggested that up to one-fifth of patients with the disease are associated with exposure to toxic pollutants.

The 290-page report was prepared by the Committee for the Medicinal Effects of Air Pollutants (COMEAP), chaired by Professor Frank Kelly of Imperial College London.

Researchers looked at 70 human studies from the general public, including population-based studies and laboratory experiments.

It has been known for decades that air pollutants can contribute to heart disease, stroke, and other circulatory problems by making blood vessels tighter and stiffer.

Scientists theorized that this process could also lead to vascular dementia, which is caused by damage to blood vessels in the brain and is the second most common form of the disease after Alzheimer’s disease.

In the report, the researchers write that evidence for this has grown stronger over the past 15-20 years.

They concluded: “We think there are strong arguments for the effects of air pollutants on the cardiovascular system with a secondary effect on the brain.

‘…We think it’s reasonable for such effects to affect blood flow to the brain. It seems plausible to us that such an effect could lead to brain damage.

“Therefore, we believe that the association between exposure to air pollutants and effects on cognitive decline and dementia may be attributable to this mechanism.”

The most dangerous form of air pollution is known as PM2.5, which is less than 2.5 micrometers in diameter.

It is one-fourth of a millimeter, or about 3 percent of the width of a human hair.

Some scientists believe that PM2.5 may have a direct effect on the brain and travel directly from the lungs to the brain via the bloodstream.

The available evidence suggests that only a small fraction of the tiny particles can cross the blood-brain barrier, the report said.

And it’s unclear whether enough of them will enter the brain and do enough damage to cause dementia.

However, the researchers found that once in the brain, particles are only slowly removed or not expelled at all.

“This clearly supports the idea that particulate matter terminating in the brain can have adverse effects,” they wrote.

Animal studies have shown that diesel engine exhaust triggers an inflammatory response in the brain and damages cells. But it’s not clear how this translates to humans.

“We believe that the current scientific basis is insufficient to directly measure the effects of air pollutants on cognitive decline or dementia,” the researchers said.

It comes today when the government invites UK municipalities to bid from a £7m fund to find innovative ways to improve air quality in their areas.

The Air Quality Grant goes to implement measures for the benefit of schools, businesses and communities affected by high levels of pollution.

Fields can only qualify if air pollution levels exceed UK targets.

Earlier this year, the government announced that as part of Prime Minister Boris Johnson’s impending “green industrial revolution”, the legal limit for PM2.5 will be halved by 2040.

Currently, the maximum level of PM2.5 allowed in the UK is set at an annual average of 20 micrograms per cubic meter of air (mcg/m3).

However, this will be reduced to 10 mcg/m3 over the next two decades.

A 2020 report from the British Heart Foundation estimates that 15 million people – a quarter of the UK population – live in areas where average levels of toxic particles in the air exceed 10 mcg/m3.

PM2.5 concentrations average around 13 mcg/m3 in London, around 14 mcg/m3 in Birmingham and over 20 mcg/m3 in Bristol.

However, the level of pollution is fluctuating day by day, and studies show that tens of thousands of air pollution deaths worldwide were avoided during the pandemic as people drive less during lockdown.

Only rural areas, mostly located in the north and south west of England, meet the WHO recommendation of 5 mcg/3.

Ministers have repeatedly stated that leaving the EU allows them to strengthen their air pollution reduction targets.

Blok revealed that it would hit the 20 mcg/m3 target.