Where does particulate matter come from?
The health risk from particulates is a function of the size and concentration of the dose inhaled. PM10 can be breathed into the lungs, and therefore, its health effects are more severe than large particles. PM2.5 can be breathed even more deeply into the alveoli of the lungs, where they remain for a long time and can cause the greatest amount of damage. Particulate matter can reduce lung functioning and can cause or aggravate respiratory conditions, and increase the long term risk of lung cancer or other lung disease such as emphysema, bronchiectasis, pulmonary fibrosis, and cystic lungs. Fine particles also cause visibility impairment, thus affecting human welfare. PM2.5 have the greatest impact on visibility reduction because of their ability to scatter light. Much of Denver’s infamous “brown cloud” is caused by fine particles.
