Air pollution is known to cause damage to health, but did you know that it damages health on a cellular level? A study published in the journal Nature Communications showed that chemicals found in car exhaust fumes and cigarette smoke interrupt genetic factors that make cilia, which are the brush-like structures that keep mucus, dirt, and bacteria out of the lungs. Breathing in air pollution changes the way a protein called aryl hydrocarbon receptor (AhR) functions. This molecular distraction could, in turn, cause respiratory problems.

The study highlighted the importance of AhR in keeping airways healthy. AhR is active in cells that line the human airway and lungs and is crucial for cilia formation. Earlier animal studies have suggested that breathing in air pollutants make it more difficult for AhR to function properly, particularly in forming new cilia.

Researchers at the Francis Crick Institute (Crick) in London aimed to determine how AhR works and what impact pollutants have. To do this, they grew airway cells from mice and skin cells from frogs in the laboratory. The cilia both in frog skin and mouse airway cells move almost similarly like the cilia in cells in the human throat and lungs.

When the researchers exposed these animal cells to common pollutants, fewer cilia were formed. This is because the AhR responded to pollutants by trying to detox the environment instead of making new cilia. It has been known that missing cilia can lead to respiratory disease.

“When chemicals found in car exhaust fumes and cigarette smoke activate AhR it kick starts a chain reaction that diverts attention away from forming new cilia. Instead, AhR tries to start a detox programme,” explained Dr. Brigitta Stockinger, one of the leaders of the study at Crick.

The findings of the study suggest that breathing in air pollutants, such as car exhaust fumes and cigarette smoke, can lead to fewer cilia and eventually breathing problems. Having fewer cilia indicates that less mucus can be cleared out, increasing the risk of infections and breathing problems.

More on the effects of air pollution on the respiratory system

A review published in the journal Respirology provided information on the impact of pollution and respiratory health as proposed in clinical reports. In the review, the researchers found that ozone (O3) and particulate matter (PM) may trigger asthma symptoms or result in premature death, especially in older people with pre-existing respiratory or cardiovascular disease. In addition, pollutants increase the release of allergenic pollen grains, leading to a higher prevalence of pollen-induced asthma.

PM, a complex mixture of solid and liquid particles suspended in air, is released into the atmosphere when coal, diesel fuels, gasoline, and wood are burned. Chemical reactions of nitrogen oxides and organic compounds present in the environment also produce PM. PM production may also be attributed to vegetation and livestock, as well as cars, trucks, and coal-fired power plants. On the other hand, O3 occurs when the ultraviolet light interacts with both nitrogen oxides and organic compounds.

The review also discussed strategies for reducing air pollution, which included urban planning, technological developments, and the introduction of new laws by the government. If both black carbon and O3 levels were reduced, more than three million premature deaths would be prevented and crop yields would be increased by nearly 50 million tonnes every year. Improving cooking stoves would reduce the use for firewood and reduce deforestation, while reducing air pollution levels in heavy traffic areas would significantly reduce the prevalence of asthma and other respiratory diseases. Efforts to reduce air pollution will prevent further damages to the environment, but will not reverse existing damages.

A number of studies also reported that people with low antioxidant levels may take dietary supplements to reduce their susceptibility to air pollution. This suggested that dietary supplements could be a way to neutralize the effects of pollutants on health.