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

Air pollution fuels growth dementia, UK government recognized for the first time.

Toxic airborne particles from cars and fossil fuels have long been associated with a rapid rise in disease in the UK and developed countries.

Now a major review on behalf of the UK Health Security Agency has confirmed the connection after analyzing dozens of human studies.

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

They believe this is because tiny toxic particles seep into the bloodstream after they are inhaled into the lungs.

The pollutants then irritate the blood vessels and cut off blood flow to the brain. Over time, this can lead to vascular dementia.

It is also likely that, in rare cases, very fine particles of air pollution can cross the blood-brain barrier and directly damage neurons.

But that doesn’t seem like an important mechanism given the current levels of air pollution in the UK, the report says.

UK government admits for the first time that air pollution contributes to the growth of dementia (File)

The graph above shows the UK's current legal air pollution limit (far left) and plans to halve it in England by 2040 (left) to 10 µg/m3.  But this is still higher than the level recommended by the World Health Organization (WHO), which is 5 µg/m3.

The graph above shows the UK’s current legal air pollution limit (far left) and plans to halve it in England by 2040 (left) to 10 µg/m3. But this is still higher than the level recommended by the World Health Organization (WHO), which is 5 µg/m3.

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

Some studies have shown that up to a fifth of patients with this disease are associated with exposure to toxic pollutants.

The 290-page report was prepared by the Committee on Medical Exposure to Air Pollutants (COMEAP), led by Imperial College London Professor Frank Kelly.

The researchers reviewed 70 human studies, including population-based studies from the general public and laboratory experiments.

What are particulate matter and nitrogen dioxide?

Particulate matter (PM) is anything in the air other than gas.

It is made up of a huge amount of chemicals and materials, some of which can be toxic.

Due to the small size of many of the particles that make up PM, some of these toxins can enter the bloodstream and be transported throughout the body to the heart, brain, and other organs.

Therefore, exposure to PM can lead to serious health effects, especially among vulnerable groups of people such as young people, the elderly and people with respiratory illnesses.

Meanwhile, nitrogen dioxide (NO2) is a gas mainly produced by burning fossil fuels.

Short-term exposure to NO2 concentrations can cause airway inflammation and increase susceptibility to respiratory infections and allergens.

NO2 can exacerbate symptoms in those who already have lung or heart disease.

Source: Department of Environment, Food and Agriculture

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

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

In the report, the researchers said that over the past 15 to 20 years, the evidence for this has become more compelling.

They concluded: “We believe there is good reason to believe that cardiovascular exposure to air pollutants has a secondary effect on the brain.

“…we consider it likely that such effects affect the blood supply to the brain. It seems plausible to us that such an effect could well lead to brain damage.

“Therefore, we think that the relationship between exposure to air pollutants and the effect on cognitive decline and dementia may be causal in relation to this mechanism.”

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

This is one four hundredth of a millimeter, or about 3 percent of the width of a human hair.

Some scientists believe that PM2.5 may also have a direct effect on the brain, traveling directly from the lungs to the brain through the bloodstream.

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

And it’s not clear if enough of them can enter the brain and cause enough damage to cause dementia.

However, the researchers found that once in the brain, the particles are excreted very slowly, if at all.

“This is clearly an argument in favor of the assumption that particulate matter entering the brain can have detrimental effects,” they wrote.

In animal studies, diesel exhaust has been shown to cause an inflammatory response in the brain and damage cells. But it’s unclear how this translates to humans.

“We consider the current evidence base insufficient to directly quantify the effects of air pollutants on cognitive decline or dementia,” the researchers said.

The move comes as the government today invited councils across England to bid for £7 million in bank funding to find innovative ways to improve air quality in their areas.

The Air Quality Grant will focus on implementing measures that benefit schools, businesses and communities affected by high levels of pollution.

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

Earlier this year, the government announced that the legal limit for PM2.5 would be halved by 2040 as part of Prime Minister Boris Johnson’s upcoming Green Industrial Revolution.

Currently, the maximum allowable level of PM2.5 in England is set at an average of 20 micrograms per cubic meter of air (µg/m3).

But over the next two decades, it will be reduced to 10 µg/m3.

According to a 2020 report by the British Heart Foundation, 15 million people – a quarter of the UK’s population – live in areas where the average level of toxic particles in the air exceeds 10 µg/m3.

In London, PM2.5 averages around 13 µg/m3, while in Birmingham it is around 14 µg/m3 and in Bristol it is over 20 µg/m3.

Pollution levels fluctuate from day to day, however, with research showing that tens of thousands of air pollution deaths were avoided worldwide during the pandemic as people used their cars less during the lockdown.

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

Ministers have repeatedly said that leaving the EU allowed them to strengthen targets to reduce air pollution.

Block showed that he would stick to his goal of 20 µg/m3.