Where It Comes From
Coal- and oil-fired power plants, industrial boilers, refineries, metal smelters, and ship diesel; sulfur dioxide transforms in the atmosphere to sulfate (often ammonium sulfate) that can travel far [1][2].
How You Are Exposed
Breathing outdoor air during haze or high-AQI days; living/working near sources; indoor infiltration through windows and HVAC; commuting near busy roads [1][4].
Why It Matters
PM2.5 exposure is tied to asthma attacks, bronchitis, reduced lung function, heart attacks, strokes, and premature death; outdoor air pollution (including PM) is carcinogenic [1][2][3].
Who Is at Risk
Children, older adults, people with asthma, COPD, heart disease, or diabetes; pregnant people; outdoor workers; communities near industrial corridors [1][4].
How to Lower Your Exposure
Check AQI; limit strenuous outdoor activity on high-PM days; use HEPA or MERV 13+ filters; keep windows closed and HVAC on recirculate; wear a well-fitted N95 when levels are high; follow medical action plans and local alerts [1][4].