Indoor air can be made up of a variety of gases, particles, and microorganisms. Some common components of indoor air include:

  1. Oxygen: Oxygen makes up about 21% of the air we breathe.
  2. Nitrogen: Nitrogen makes up about 78% of the air we breathe.
  3. Water vapor: The amount of water vapor in the air can vary, but it is usually present in small amounts.
  4. Carbon dioxide: Carbon dioxide is present in small amounts in indoor air, but it can increase to higher levels if there are not enough windows or ventilation to allow for proper exchange of air with the outdoors.
  5. Volatile organic compounds (VOCs): VOCs are chemicals that are emitted as gases from certain solids or liquids. They can come from a variety of sources, including building materials, furniture, cleaning products, and personal care products.
  6. Particulate matter: Particulate matter includes small particles that are suspended in the air, such as dust, pollen, and mold spores.
  7. Microorganisms: Indoor air can also contain a variety of microorganisms, including bacteria, viruses, and fungi.