How do pollution particles travel through the body? Scientists finally have the answer

Pollution doesn’t just stay in your lungs – it finds its way into the rest of your body, too. We’ve known it’s linked to heart problems, strokes, and even brain issues.

But how pollution travels from the air you breathe into your organs hasn’t been totally clear – until now. A new study reveals the pathway, and the findings are unsettling.

Turns out, these pollution particles don’t just hang out in your lungs. They stick to red blood cells and move through your entire body.

Pollution particles in your blood

In this study, healthy volunteers spent an hour standing within about 30 feet of a busy road in London. Before and after the roadside exposure, researchers collected blood samples and examined them under a microscope.

What the experts found was clear. After just one hour near traffic, the number of pollution particles stuck to red blood cells doubled or tripled.

Red blood cells are responsible for picking up oxygen in your lungs and delivering it everywhere it’s needed – from your brain to your toes. If pollution particles are sticking to those cells, they’re getting a free ride across the body.

To give you a sense of scale, even though only 2 to 3 out of every 1,000 red blood cells were carrying particles, that still adds up to around 80 million polluted red blood cells in an average adult—after standing near traffic for just one hour.

The power of a good mask

The study was conducted by researchers at Queen Mary University of London. The team used a small air-monitoring device called an aethalometer, which the volunteers wore throughout the experiment.

The device measured how much particle pollution was in the air the participants were breathing. They first spent four hours indoors in an office building.

Next, the volunteers stood by a busy road for an hour, and finally went back inside for another hour.

According to the results, the roadside air contained nearly five times more pollution than the indoor air.

The scientists repeated the test with some volunteers wearing an FFP2 mask – the kind used for fine particle protection.

The results were telling. While the air pollution levels were the same, the people who wore the masks didn’t have increased pollution levels on their red blood cells. In other words, the particles didn’t get through.

Pollution sticks – no matter the species

To back up what they saw in humans, the researchers ran lab tests too. They exposed both human and mouse red blood cells to diesel exhaust particles.

Just like in the volunteers, the particles stuck to the cells – and the more particles they added, the more they found on the cells.

The experts took a closer look at the particles stuck to the blood cells and analyzed their composition.

These weren’t just random bits of dust. They included iron, copper, silicon, chromium, and zinc – common elements in car exhaust.

The researchers also found silver, copper, and molybdenum, which come from brake and tire wear. All of the particles were smaller than 2.5 micrometers – known as PM2.5 – which are small enough to pass deep into the lungs.

Pollution traveling in our bodies

“In our bodies, red blood cells work by collecting oxygen from our lungs and delivering it throughout the body,” said Professor Jonathon Grigg, who led the study.

“With this set of experiments, we have shown that tiny air pollution particles are hijacking our red blood cells, meaning they can also travel almost anywhere in the body.”

“We’re finding more and more evidence that air pollution particles are making their way into many different organs of the body and now we have clear evidence of how that could be happening.”

Professor Grigg noted that the technique used in the study is a relatively simple way to measure the amount of pollution entering the body, so it is now possible to test out which factors might increase or reduce the problem.

“We were surprised to find how well an FFP2 face mask prevents these very tiny particles from reaching and attaching to blood cells,” he added.

The bigger problem we can’t ignore

Professor Ane Johannessen from the European Respiratory Society highlighted the significance of the research.

“These tiny particles are produced by vehicles and industrial processes and released into the air we breathe. This study sheds light on how these dangerous particles might be infiltrating every part of the body via the bloodstream,” said Johannessen.

“It also suggests we could lower the risk with the right protective facemask. This could be beneficial for people who are vulnerable because they have a lung disease, or they cannot avoid spending time next to a busy road.”

However, noted Johannessen, most of us cannot avoid being exposed to dangerously high levels of air pollution in our daily lives, so we need laws to dramatically lower air pollution and reduce the risk for everyone.

The full study was published in the journal ERJ Open Research.

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