![]() You can use air quality alerts to protect yourself and others when PM reaches harmful levels:ĪirNow: Every day the Air Quality Index (AQI) tells you how clean or polluted your outdoor air is, along with associated health effects that may be of concern. Learn about how air quality standards help reduce PM. Particles of sand and large dust, which are larger than 10 micrometers, are not regulated by EPA.ĮPA’s national and regional rules to reduce emissions of pollutants that form PM will help state and local governments meet the Agency’s national air quality standards. Learn more about health and environmental effects What is Being Done to Reduce Particle Pollution?ĮPA regulates inhalable particles. Of these, particles less than 2.5 micrometers in diameter, also known as fine particles or PM 2.5, pose the greatest risk to health.įine particles are also the main cause of reduced visibility (haze) in parts of the United States, including many of our treasured national parks and wilderness areas. Some particles less than 10 micrometers in diameter can get deep into your lungs and some may even get into your bloodstream. Particulate matter contains microscopic solids or liquid droplets that are so small that they can be inhaled and cause serious health problems. Most particles form in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides, which are pollutants emitted from power plants, industries and automobiles. Some are emitted directly from a source, such as construction sites, unpaved roads, fields, smokestacks or fires. These particles come in many sizes and shapes and can be made up of hundreds of different chemicals. ![]() The average human hair is about 70 micrometers in diameter – making it 30 times larger than the largest fine particle. How small is 2.5 micrometers? Think about a single hair from your head.PM 2.5 : fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.PM 10 : inhalable particles, with diameters that are generally 10 micrometers and smaller and.Others are so small they can only be detected using an electron microscope. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. PM stands for particulate matter (also called particle pollution): the term for a mixture of solid particles and liquid droplets found in the air.
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