Ambient particulate matter (PM) is the number one environmental constituent related to premature death, causing approximately three million premature deaths/year globally, and particularly in the WHO Southeast Asia and Western Pacific regions.

The respiratory system is the most obvious first target, and high PM is associated with increased episodes of asthma attacks, exacerbation of chronic obstructive pulmonary disease, pulmonary infection as well as lung cancer. But an important indirect target is the cardiovascular system, with an increase in myocardial infarction, stroke, arrhythmia and acute heart failure, as well as atherosclerosis.