On October 17, 2013, the International Agency for Research on Cancer, a subsidiary of the World Health Organization, issued a report for the first time that air pollution is carcinogenic to humans, and the main substance of air pollution is particulate matter.
In the natural environment, the particulate matter in the air mainly includes sand and dust brought by the wind, volcanic ash ejected by volcanic eruptions, smoke and dust caused by forest fires, sea salt evaporated from seawater exposed to sunlight, and pollen of plants.
With the development of human society and the expansion of industrialization, human activities also emit a large amount of particulate matter into the air, such as soot from various industrial processes such as power generation, metallurgy, petroleum, and chemistry, cooking fumes, exhaust from automobiles, smoking etc.
The particulate matter in the air needs to be most concerned about inhalable particulate matter, which refers to the particulate matter with an aerodynamic equivalent diameter of less than 10 μm, which is PM10 we often hear about, and PM2.5 is less than 2.5 μm.
When air enters the human respiratory tract, the nasal hair and nasal mucosa can generally block most of the particles, but those below PM10 cannot. PM10 can accumulate in the upper respiratory tract, while PM2.5 can directly enter the bronchioles and alveoli.
Due to its small size and large specific surface area, particulate matter is more likely to adsorb other substances, so the causes of its pathogenesis are more complicated, but the most important one is that it can cause cardiovascular disease, respiratory disease and lung cancer.
PM2.5, which we usually care about, actually accounts for a small proportion of inhalable particles, but why pay more attention to PM2.5?
Of course, one is due to media publicity, and the other is that PM2.5 is finer and easier to absorb organic pollutants and heavy metals such as polycyclic aromatic hydrocarbons, which significantly increases the probability of carcinogenic, teratogenic, and mutagenic.
Post time: Mar-16-2022