PM2.5 is measured in micrograms per cubic meter (μg/m³), which means the weight of all particles smaller than or equal to 2.5 μm within each cubic meter is calculated. A higher value indicates a higher concentration of fine particulate matter in the air, indicating more pollution.

Numerous studies have confirmed the harmful effects of suspended particles on the respiratory and cardiovascular systems, leading to conditions such as asthma, lung cancer, cardiovascular diseases, birth defects, and premature death. High PM2.5 exposure during pregnancy has also been linked to increased blood pressure in children.

One study published in the "Journal of the American Medical Association" suggests that PM2.5 can lead to the deposition of arterial plaque, causing vascular inflammation and atherosclerosis, ultimately leading to heart disease and other cardiovascular problems. This long-term study, initiated in 1982, established that when the concentration of PM2.5 in the air remains above 10 μg/m³ for extended periods, it increases the risk of mortality.