Particulate matter (PM) refers to a complex mixture of microscopic solid or liquid particles suspended in the air. These particles can come from both human-made and natural sources and vary greatly in size, composition, and origin. They can be classified into different categories based on their diameter, including PM10 (particles with a diameter of 10 micrometers or less) and PM2.5 (particles with a diameter of 2.5 micrometers or less).
Particulate matter can originate from industrial processes, vehicle exhaust, construction activities, wildfires, and dust storms, among other sources. Additionally, it can also result from chemical reactions in the atmosphere involving gases emitted by various sources. The composition of particulate matter includes a wide range of substances, such as soot, dust, pollen, allergens, mold spores, metals, organic chemicals, and even microorganisms.
These tiny particles are of concern due to their potential to adversely affect human health and the environment. When inhaled, particulate matter can penetrate deep into the respiratory system, causing or exacerbating respiratory and cardiovascular issues, such as asthma, bronchitis, and heart disease. Moreover, certain types of particulate matter are associated with a higher risk of developing lung cancer.
Particulate matter can also contribute to reduced visibility, creating haze or smog, and can deposit on surfaces, causing soiling and corrosion. In addition, it can influence climate by influencing the radiative balance of the Earth's atmosphere and even act as cloud condensation or ice-nucleating particles.
Due to the detrimental effects of particulate matter on public health, it is regularly monitored by environmental agencies worldwide, and efforts are made to mitigate its emissions and reduce exposure through air quality regulations and control measures.
