PM2.5 stands for particulate matter that has a diameter of 2.5 micrometers or less. These fine inhalable particles are a type of particle pollution that can be found in the air and can pose a significant risk to human health. PM2.5 can be made up of hundreds of different chemicals and can come from various sources, including human activities such as residential cooking, smoking, and emissions from cars and trucks.
Breathing in unhealthy levels of PM2.5 can increase the risk of cardiovascular and respiratory hospital admissions, emergency department visits, and deaths. Long-term exposure to fine particles can cause increased mortality from heart disease and may be associated with increased rates of chronic bronchitis, reduced lung function, and lung cancer. Children living in communities with high levels of PM2.5 have slower lung growth and smaller lungs at age 18 compared to children who lived in communities with low PM2.5 levels.
The Environmental Protection Agency (EPA) has established National Ambient Air Quality Standards for PM2.5 to be protective of public health. The short-term standard (24-hour or daily average) is 35 micrograms per cubic meter of air (µg/m3), and the long-term standard (annual average) is 12 µg/m3.
To reduce exposure to PM2.5, it is recommended to spend more time indoors where particle pollution levels are usually lower, choose easier outdoor activities, and avoid busy roads and highways where PM is usually worse because of emissions from cars and trucks.
