Particles, also known as particulate matter (PM), are a combination of solid particles and liquid droplets that are airborne1. The particles can come in a range of sizes and compositions2. Ultra fine particles are typically less than one micron (one millionth of a meter) in diameter, requiring a microscope to be seen, while larger particles, such as dust or smoke, can be seen with the naked eye. Particles can be made of one single chemical or many.
Particles can form spontaneously in the air or as the result of some other process, such as combustion. Indoors, sources of combustion constitute a major source of indoor particulate matter. Fireplaces, stoves, kerosene heaters, candles, and cigarettes all provide a source of combustion, and therefore, a source of particles3,4.
Exposure to particles has been linked with a variety of respiratory healthy effects. Particulate matter itself can act as an irritant to the eyes, nose, and throat3. Furthermore, particles act as vehicles for a variety of chemicals and microbial organisms, ushering them into the respiratory tract upon inhalation (Figure 1). Organisms like microbes and viruses can lead to respiratory infections and bronchitis, and in extreme cases, chemicals such as radon can promote lung cancer.
Figure 1: Health Effects of Particles6
Particle levels can vary significantly in different homes. Where there are sources of combustion, such as smoking or a gas stove, there will be more particles than a similar home without smoking or other strong particle sources3. Particle levels are also dependent upon outdoor concentrations, so it is expected that in regions of higher outdoor particle pollution, that indoor particle levels will be higher as well.
Below are some steps recommended by the United States Environmental Protection Agency (EPA) to reduce your exposure to particles3,5.
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