Self-portrait breathing in particulate matter. Photograph of electron micrograph of particles from London air. Original magnification of PM is X 13,000 (Waller, 1963) 

  

Particulate matter (PM) is everything in the air that is not a gas and therefore consists of a huge variety of smog particles, some of which can be toxic. Due to the small size of many of the particles called PM 2.5, they can enter the bloodstream and be transported around the body, lodging in the heart, brain and other organs. Therefore, exposure to PM can result in serious impacts to health, especially in vulnerable groups such as the young, the elderly and those with respiratory problems.