To All Research Can You See Almaty’s Smog in Your Own Blood?
Inspired by a BBC journalist’s experience and a study by Queen Mary University of London, the Almaty Air Initiative foundation conducted its own experiment with volunteers to explore a question: can the particles we breathe in on Almaty’s busy streets be seen in our blood?
On a sunny morning in early September, outside peak rush hour, five volunteers, each a clean-air advocate in their own way, took part in an Almaty Air Initiative experiment. They gave blood samples before and after an hour-long walk along the roads within the block bounded by the busy Satpayev, Zharokov, Abay and Rozybakiyev streets. Two participants wore KN95 masks from the outset and throughout the experiment; three walked the route without respirators. After the walk, soot particles were detected under a microscope on individual red blood cells in all three participants who had walked without respirators.
Numerous studies show that fine particles inhaled by humans enter the bloodstream. Almaty Air Initiative researchers decided to find out whether they could see them under a microscope. To the participants’ surprise, we did indeed observe black particles on red blood cells. Our results are consistent with the Queen Mary University of London study (можно дать сноской в конце текста инфо о проекте и сделать гиперссылку на первоисточник): the university’s researchers confirmed that traffic-related particles can reach the bloodstream and that an FFP2 respirator (KN95, KN99) significantly reduces exposure to them.
An image of a blood sample taken under a light microscope during the Almaty experiment. Photograph by Bauyrzhan Bismildin
In 2025, the annual average PM2.5 concentration in Almaty was 31.2 µg/m³, 6.3 times the World Health Organization’s annual guideline level. For city residents, however, such data often remain abstract: numbers in an app, a graph or a grey band above the city. In its new experiment, Almaty Air Initiative shows what happens after we breathe in and why air pollution affects much more than just the lungs.
PM2.5 is a mixture of solid particles and liquid droplets up to 2.5 micrometres in diameter, more than 30 times thinner than a human hair. Near roads, it includes exhaust particles and particles produced by wear on brakes, tyres and road surfaces. The smallest fractions can penetrate deep into the lungs, while some ultrafine particles can cross the lung barrier, enter the bloodstream and travel through it to the liver, brain, heart and other vital organs.
How the Almaty Experiment Was Conducted
Five members of the foundation’s staff and friends took part in the experiment.
Zhuldyz Saulebekova – Executive Director of Almaty Air Initiative,
Sayyna Antonova – Data Analyst at Almaty Air Initiative (wore a protective mask throughout the experiment),
Mukhtar Yerlan – comedian and actor who appeared in the environmental stand-up comedy show about smog, “Taza äzilder”,
Pakizat Saylaubekova – environmentalist who addresses Almaty’s air pollution in her public talks (wore a protective mask throughout the experiment),
Aizhuldyz Abykeyeva – journalist at Almaty Today who regularly raises the issue of Almaty’s air quality in her reporting.
First, blood samples were taken from all participants, who had arrived wearing protective respirators. They then spent an hour walking along the roads within the block bounded by Satpayev, Zharokov, Abay and Rozybakiyev streets. Our portable sensor showed that the PM2.5 concentration there at the time was 10–15 µg/m³, within the WHO’s daily guideline level. After completing the route, the participants gave blood samples again.
The samples were prepared on microscope slides and examined using a laboratory light microscope. Photographer Bauyrzhan Bismildin helped us photograph the microscopic fields so that we could compare the before-and-after images in detail.
Taking a blood sample
Prepared slides before microscopic examination
The laboratory microscope used for visual analysis and photography
What We Saw
After the walk, small dark particles were found on red blood cells in the blood samples of all three participants who had walked the hour-long route without respirators: Zhuldyz, Mukhtar and Aizhuldyz.
Microscope images of blood smears. Small dark particles and inclusions are visible on individual red blood cells
What the Queen Mary Study Found
The original study, conducted near roads in London, involved 12 adult volunteers. After spending four hours in an office, they spent an hour within ten metres of a busy road. Personal exposure to black carbon (PM2.5) was measured with a portable device, and blood was collected before roadside exposure, immediately afterwards and an hour later. The researchers analysed 3,000 red blood cells per participant.
Photographs of red blood cells from the Queen Mary University experiment
After an hour beside the road, the researchers observed that the number of visible particles had more than doubled. The higher the personal exposure to black carbon, the greater the area of particles associated with red blood cells. Using electron microscopy and elemental analysis, the researchers confirmed the presence of carbon-containing and metal-containing particles characteristic of traffic pollution.
As part of the same experiment, eight volunteers repeated the roadside exposure while wearing FFP2 respirators, equivalent to KN95 or N95. Pollution levels around them were comparable to those during exposure without a respirator, but the median area of particles associated with red blood cells was approximately 64% lower. The difference was statistically significant. The study’s authors drew a clear conclusion: FFP2 reduces the dose of inhaled traffic-related particles reaching the bloodstream.
This is an important finding with practical relevance for Almaty. On days with high pollution, and during prolonged periods near busy roads, a well-fitting respirator helps reduce the amount of fine particles a person inhales. The World Health Organization recommends choosing certified FFP2, N95 or KN95 respirators and ensuring that they fit closely to the face.
To provide maximum protection, respirator masks must be used correctly:
- an ordinary cloth or surgical mask is not equivalent to an FFP2, N95 or KN95 respirator;
- the respirator must cover the nose and mouth without noticeable gaps around the edges;
- a filtering respirator traps particles but does not protect against gaseous pollutants, including carbon monoxide and nitrogen dioxide;
- the respirator must be replaced according to the manufacturer’s instructions, and whenever it becomes wet, dirty or damaged, or no longer fits properly.
A respirator is an additional, temporary measure for periods of high pollution. The main way to protect the health of the city as a whole is to reduce emissions at their sources.
How Do Particles Travel Beyond Our Lungs?
After inhalation, the smallest particles reach the alveoli, the parts of the lungs where air is separated from blood by a very thin barrier. Experiments with labelled nanoparticles show that some ultrafine particles can cross this barrier and appear in the blood within minutes or hours.
The Queen Mary study revealed one possible route for their onward movement: carbon-containing and metal-containing particles attach to the surface of red blood cells and circulate with them through almost the entire body. Researchers have yet to establish whether this is the main route or exactly how such attachment affects red blood cell function in humans.
The harm caused by pollution is not limited to the physical presence of particles in the blood. PM2.5:
– triggers oxidative stress and inflammation,
– affects blood vessel walls, blood clotting and the regulation of heart function.
These mechanisms help explain the consistent association between air pollution and lung disease, heart attacks, strokes, arrhythmias and cardiovascular mortality.
Why This Matters for Almaty
In a city where annual average PM2.5 levels exceed the WHO guideline by more than six times, pollution can easily be seen as part of the everyday background. Now we have seen a tangible link between the air outside and processes inside the body. Scientific evidence shows that some of the fine particles we inhale can reach the bloodstream.
That is why, during periods of high pollution, exposure to polluted air can be reduced by:
– monitoring air quality,
– spending less time near heavy traffic and sources of solid-fuel combustion whenever possible,
– wearing a well-fitting FFP2, N95 or KN95 respirator.
At the same time, Almaty needs systemic measures to reduce emissions so that residents do not have to rely on personal protection.
Participants’ Reflections
Zhuldyz Saulebekova, Executive Director of Almaty Air Initiative
“The most striking thing was that we saw these particles with our own eyes, right on the red blood cells. The blood then carries them around the body. What we breathe in does not stay in the lungs.”
Sayyna Antonova, Data Analyst at Almaty Air Initiative
“I work with PM2.5 data every day, but a graph and an image of your own red blood cells under a microscope feel completely different.”
Pakizat Saylaubekova, environmentalist
“I walked the entire route wearing an FFP2 because it was important to compare what we observed in participants with and without respirators. The participants’ results confirmed that a protective mask works. I see the value of this experiment in how clearly it illustrates a mechanism already confirmed by scientific research and explains why it makes sense to use a suitable respirator on days with high pollution. I will definitely be buying more masks for Almaty’s peak smog season now.”
Yerlan Mukhtar, stand-up performer
“It is easy to see smog as part of Almaty’s everyday background. After this experiment, it stopped being just a grey band above the city for me: I saw that even an hour on busy streets can show up in images of your blood.”
Aizhuldyz Abykeyeva, journalist at Almaty Today
“As a journalist, it was important for me to see the whole journey, from the city street to the laboratory. The most convincing thing here is not an individual photograph, but its connection to scientific research and the practical takeaway: a properly chosen respirator really does reduce exposure to fine particles.”
Sources
[1] Almaty Air Initiative. What Was the Air Like in Almaty in 2025?
[4] World Health Organization. Personal-level actions to reduce air pollution exposure. 2024