Indoor air pollution falls into a few broad categories: particles (aka particulate matter), gases, biological, chemical, and radiation. Often the sources are a mix of these.
Particulate Matter #
Particulate matter (PM) are tiny particles suspended in the air. These include dust and smoke, which are from cooking, cleaning, and smoking. The size of these particles that scientists are concerned with are very small — 30 times smaller than a human hair. They can get deep in the lungs causing irritation and disease. This is often written as PM2.5, which means we want to detect and remove particles down to 2.5 microns in diameter.
Gaseous Pollutants #
Gaseous pollutants can be a major contributor to poor indoor air quality. To reduce exposure to gaseous pollutants indoors, provide proper air, especially when using combustion appliances like gas stoves, furnaces, or fireplaces. Gases come from combustion appliances, building materials, and outdoor air pollution. Common gases include:
- Carbon monoxide (CO)
- Nitrogen dioxide (NO2)
- Sulfur dioxide (SO2)
- Ozone (O3)
Biological Pollutants #
Biological pollutants include flammable and volatile organic compounds, animal dander, dust mites, cockroaches, pollen, mold and mildew, viruses, and bacteria. They can trigger sneezing, watery eyes, coughing, shortness of breath, fever, digestive issues, and more. Their presence can also increase the risk of contracting an infection.
Chemical Pollutants #
Chemical pollutants include a wide range of chemicals, such as formaldehyde, volatile organic compounds (VOCs), asbestos, lead, and pesticides. These can be released into indoor air from a lot of sources like building materials, furnishings, consumer products, and outdoor air pollution.
Radiation #
Radiation refers to energy emitted as waves or particles, which can travel through space and matter. There are two kinds: ionizing and non-ionizing.
Ionizing radiation has enough energy to knock electrons out of atoms, creating ions. This type of radiation can harm human health. It can cause DNA damage, leading to an increased risk of cancer and other health problems. Examples of sources include X-rays, gamma rays, and radon gas.
Non-ionizing radiation does not have enough energy to ionize atoms. This is often thought to be less harmful to human health, but can still impact health at high levels of exposure. Examples of sources include radio waves, microwaves, and visible light.
Indoor exposure can occur from natural sources such as radon gas in the soil, building materials, X-ray machines, electronic devices, and even tobacco smoke.
To reduce exposure to radiation indoors, it’s important to test for and mitigate high levels of radon gas, and to choose building materials and consumer products that have low levels of radioactive elements. Proper shielding and ventilation can also help to reduce exposure to radiation from X-ray machines and other sources of ionizing radiation.