What Is Indoor Air Quality?

Indoor air quality is just as important as outdoor air quality. Outdoor air can contain harmful pollution. But indoor air can actually be worse than outdoor air. When you’re managing asthma and allergies, you should take steps to make sure your indoor air quality is healthy.

The following can affect indoor air quality:

  • Allergens
  • Scents, chemicals and volatile organic compounds (VOCs)
  • Outdoor air pollution


Indoor air can have a lot of allergens, like dust mites, pets, cockroaches and mold.

Dust mites are tiny creatures that can be found in many homes. They thrive in furniture, carpets and bedding.

People with pet allergies are usually allergic to proteins in the pet’s urine, saliva or dander (dead skin cells). Pet allergens can collect on many surfaces. Sometimes the allergens may remain at high levels for several months and cling to walls, furniture, clothing and other surfaces.

Dust mites and pet dander can be found on:

  • Surfaces
  • Fabric furniture
  • Curtains, throws and pillows
  • Carpets and rugs
  • Bedding
  • Under and on top of furniture
  • Among clutter

Mold is a fungus that can be found both indoors and outside. Outdoors, you can find it on rotting wood, damp leaves, and on grasses and grains. When a mold source is disturbed, it can send spores into the air where they can make their way into your sinuses and lungs.

Inside, mold can be found:

  • Near sinks, showers and toilets
  • Near water leaks, such as from appliances, pipes and roofs
  • In basements and damp or humid areas of your home
  • In the soil of overwatered house plants
  • On produce

Cockroaches can cause asthma and allergy symptoms year-round. They like warm conditions, damp places and food sources. Even dead cockroaches can cause reactions.

Scents, Chemicals and Other Sources of Indoor Air Pollution

Scents, both good and bad, can affect your indoor air quality. Any kind of scent could trigger asthma symptoms. These can include scented candles, potpourri, perfumes, wax warmers and cleaning supplies.

Some other items in your home can release gasses called VOCs. This is called offgassing. VOCs can be 2 to 5 times higher indoors than outdoors.1 VOCs can have some short-term effects, but experts aren’t sure yet of long-term effects.

Sources of VOCs can include:

  • New furniture
  • New mattresses
  • New carpet
  • New building materials
  • Paint and varnish
  • Cleaning supplies
  • Air fresheners
  • Pesticides

Other sources of indoor air pollution include:

  • Fuel-burning heat sources (like wood-burning stoves, kerosene heaters)
  • Smoke from cooking, candles, fireplaces or tobacco
  • Attached garages that store cars, motorcycles or lawnmowers (can add carbon monoxide to your air)
  • Radon (a gas that comes from the ground and enters a home and can rise to dangerous levels)

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Outdoor Air Pollution

Outdoor air pollution is caused by particles and gasses that are not normally part of the air. This can come from pollen, smoke, dust, ozone and emissions from cars and factories. All of these can create poor outdoor air quality.

Bad outdoor air quality can make asthma and allergies worse. And bad air can easily enter your home. No home is completely air tight. Outdoor air can come in through leaks around doors and windows. It can also come in every time you open a window or door. You can bring pollen and smoke particles inside on your clothing.

Allergens, scents, chemicals and outdoor air in your home all work together to affect your indoor air quality.

How Can I Improve the Air Quality in My Home?

improving indoor air quality Bedroom

Read about ways to improve the air quality in your bedroom.

improving indoor air quality Livingroom

Read about ways to improve the air quality in your living room.

improving indoor air quality Kitchen

Read about ways to improve the air quality in your kitchen.


1. Volatile Organic Compounds’ Impact on Indoor Air Quality. (2017, April 19). Retrieved September 14, 2017, from https://www.epa.gov/indoor-air...t-indoor-air-quality