Most Common Indoor Air Pollutants and Sources

Sources
Biological contaminants are, or are produced by, living things are small enough to be inhaled.

• pollens, which originate from plants
• viruses, which are transmitted by people and animals
• mold
• bacteria, which are carried by people, animals, and soil and plant debris
• household pets, which are sources of saliva and animal dander (skin flakes)
• droppings and body parts from cockroaches, rodents and other pests or insects
• viruses and bacteria
• The protein in urine from rats and mice is a potent allergen. When it dries, it can become airborne.
• Contaminated central air handling systems can become breeding grounds for mold, mildew and other sources of biological contaminants and can then distribute these contaminants through the home

Health Effects from Biological Contaminants
Some biological contaminants trigger allergic reactions, including:

• hypersensitivity pneumonitis
• allergic rhinitis
• some types of asthma

Infectious illnesses, such as influenza, measles and chicken pox are transmitted through the air. Molds and mildews release disease-causing toxins. Symptoms of health problems caused by biological pollutants include:

• sneezing
• watery eyes
• coughing
• shortness of breath
• dizziness
• lethargy
• fever
• and digestive problems

Children, elderly people and people with breathing problems, allergies, and lung diseases are particularly susceptible to disease-causing biological agents in the indoor air.

Mold, dust mites, pet dander and pest droppings or body parts can trigger asthma. Biological contaminants, including molds and pollens can cause allergic reactions for a significant portion of the population. Tuberculosis, measles, staphylococcus infections, Legionella and influenza are known to be transmitted by air.

Reducing Exposure to Biological Contaminants

Adequate ventilation and good air distribution also help. If mold is a problem, clean up the mold and get rid of excess water or moisture. Maintaining the relative humidity between 30% – 60% will help control mold, dust mites and cockroaches. Employ integrated pest management to control insect and animal allergens.

• Install and use exhaust fans that are vented to the outdoors.
  There are exhaust fans on the market that produce little noise, an important consideration for some people. Another benefit to using kitchen and bathroom exhaust fans is that they can reduce levels of organic pollutants that vaporize from hot water used in showers and dishwashers.
• Ventilate the attic and crawl spaces to prevent moisture build-up.
  Keeping humidity levels in these areas below 50 percent can prevent water condensation on building materials.
• If using cool mist or ultrasonic humidifiers, clean appliances according to manufacturer’s instructions and refill with fresh water daily.
  Because these humidifiers can become breeding grounds for biological contaminants, they have the potential for causing diseases such as hypersensitivity pneumonitis and humidifier fever. Evaporation trays in air conditioners, dehumidifiers and refrigerators should also be cleaned frequently.
• Thoroughly clean and dry water-damaged carpets and building materials (within 24 hours if possible) or consider removal and replacement.
  Carpets and building materials can harbour mold and bacteria. It is very difficult to completely rid such materials of biological contaminants.
• Keep the house clean. House dust mites, pollens, animal dander and other allergy-causing agents can be reduced, although not eliminated, through regular cleaning.
  People who are allergic to these pollutants should use allergen-proof mattress encasements, wash bedding in hot (54° C) water and avoid room furnishings that accumulate dust, especially if they cannot be washed in hot water. Using central vacuum systems that are vented to the outdoors or vacuums with high efficiency filters may also be of help.
• Take steps to minimize biological pollutants in basements.
  Clean and disinfect the basement floor drain regularly. Do not finish a basement below ground level unless all water leaks are patched and outdoor ventilation and adequate heat to prevent condensation are provided. Operate a dehumidifier in the basement if needed to keep relative humidity levels between 30 – 50 percent.

Indoor Dust

Indoor dust can be easily kicked up into the air by cleaning, vacuuming, and other activities like walking and crawling. Children are exposed to more indoor dust than adults. This is because they crawl and play closer to the floor, where the dust that accumulates on surfaces can be inhaled more easily. Also, they often put their hands, toys, and other items into their mouths. Children also eat, breathe, and drink more relative to their body mass than adults do.

Indoor dust may contain:

• Outdoor soil and dust that has been blown or tracked indoors;
• Biological particles, also known as biological contaminants, including pollen, mold spores, pet dander, dust mites, and human skin flakes and hair;
• Particles from human activities, such as cooking, cleaning, and burning candles; 
• Particles from consumer and personal care products; 
• Plastics, flame retardants, and pesticides; and 
• Sometimes industrial chemicals and heavy metals, such as lead.

Actions You Can Take

• Frequent cleaning and ventilation are effective ways to reduce dust and other pollutants.
  • Vacuum carpets and furniture every week with a central vacuum system, or more often.
  • Dust often with a damp cloth. Dampening the cloth helps keep settled dust from going back into the air.
  • Consider using a vacuum with a HEPA filter to reduce dust build-up. A HEPA filter can help keep some vacuumed dust from escaping the vacuum cleaner back into the air. 
  • People with asthma or allergies should leave the area being vacuumed to avoid breathing in dust that is stirred up during vacuuming.
• Routinely change air filters in HVAC systems (central heating and cooling systems) and in portable air cleaners according to the manufacturer’s directions.
• Upgrade HVAC filters. Higher-efficiency filters in central heating and cooling systems and portable air cleaners can reduce harmful pollutants such as indoor PM. You can learn more about air cleaners and air filters in the home. 
• Take steps to prevent and reduce exposure to biological contaminants.
• If your home contains lead or asbestos, you should use extra caution and take additional steps to safely address indoor dust concerns. 
• If you are remodeling your home, follow best practices for indoor air quality to contain dust and other pollutants while you work. 

Mold
Indoor mold can be problematic if it is left to grow in large areas, like in carpets or walls. Excessive mold indoors indicates there is too much moisture in the building. Indoor mold can be problematic if it is left to grow in large areas, like in carpets or walls. Excessive mold indoors indicates there is too much moisture in the building.