Particle pollution and health risks

Particle pollution, also known as particulate matter or PM, is a mixture of solid and liquid droplets suspended in the air. These particles can be made up of various components, including acids, inorganic compounds, organic chemicals, soot, metals, soil or dust particles, and biological materials. Both indoor and outdoor air contain particle pollution, with some particles visible to the naked eye and others too small for the unaided eye.

Particles can be categorized into two main groups: coarse particles (PM10-2.5) and fine particles (PM2.5). Coarse particles have diameters larger than 2.5 µm and smaller than or equal to 10 µm. Fine particles, on the other hand, are generally 2.5 µm in diameter or smaller, including ultrafine and nanoparticles with diameters less than 0.1 µm. PM10 encompasses all particle fractions.

Primary particles are emitted directly from sources like construction sites, unpaved roads, smokestacks, and fires. Secondary particles form through atmospheric reactions involving chemicals such as sulfur dioxides and nitrogen oxides, emitted from power plants, industries, and automobiles. Human activities like cooking, smoking, dusting, and vacuuming, particularly indoors, can also produce particle pollution.

Particle pollution is present everywhere, not just in haze, smoke, and dust. It can occur year-round and is a problem even in air that appears clean. High concentrations of particle pollution can arise near busy roads, in urban areas, industrial zones, during smoky weather from wood stoves, fireplaces, campfires, or wildfires, and on calm days when air pollution accumulates, such as during hot, humid, and stagnant conditions.

Once inhaled, fine particles can penetrate deep into the lungs, while some ultrafine particles may even enter the bloodstream. This can lead to adverse health effects, including respiratory, cardiovascular, metabolic, autoimmune, neurological diseases, and cancers. Vulnerable groups include individuals living close to emission sources, pregnant people, infants, children, teenagers, older adults, those with pre-existing lung or cardiovascular diseases, obese individuals, diabetics, smokers, people with lung cancer, those with low socioeconomic status, and people of color.