What are you breathing? What are Indoor Air Pollutants?

This data has been gathered from US  Environmental Protection Agency (EPA)
If you face issues with these pollutants you can consult EPA website for more information and solutions.
You can eliminate the source, or reduce their impact, using adequate ventilation and air cleaners.
These are some common sources of household indoor air pollution:

Pet Dander and Hair
Pets can trigger allergy and asthma attacks due to dander and hair. Keep them out of the sleeping areas, and away from upholstered furniture, carpets, and stuffed toys. Vacuum and clean carpets, rugs, and furniture often.

Secondhand Smoke
Secondhand smoke from cigarettes, cigars, and other tobacco products can trigger asthma and other respiratory illnesses especially in children. To help protect children from secondhand smoke, do not smoke or allow others to smoke inside your home or car.

Mold
Bathrooms are a common source of mold. Humidity from showers can cause moisture problems, which will lead to mold growth. Mold can cause allergic reactions, asthma, and other respiratory ailments. Installing and using a ventilation fan will help to control moisture and inhibit mold growth.

In air tight homes, windows and doors seal to save energy. Moisture can get trapped and condensate around windows when indoor air is warmer than outside. This can cause mold in areas surrounding the window. It is difficult to see, because window coverings can hide these areas. This mold may look like fine black dust or spots. Do not blow this into the air by wiping or vacuuming. It requires handling with protection. There are natural home solutions that you can use to clean. Wear gloves and a face mask. Rinse everything properly.
Ventilate on a regular basis. Dehumidifiers in living spaces can help prevent moisture buildup.

Dust
Dust mites can trigger allergy and asthma attacks. Dust mites are everywhere especially on pillows, blankets, carpets, upholstered furniture, and stuffed toys Dust and vacuum your home regularly, wash bedding, and use allergen-proof mattress and pillow covers.

Pesticides and herbicides
Most of these chemicals can irritate the eyes, nose, and throat; damage the central nervous system and kidneys; and increase the risk of cancer. Don’t leave food out, and if you must use them, ventilate during and after use and follow directions to limit exposure. Use non-chemical methods of pest and weed control as much as possible.

Volatile Organic Compounds (VOCs)
Common household cleaners, often placed under the kitchen sink, release Volatile Organic Compounds (VOCs), when used and stored. Store household products that contain chemicals according to manufacturers’ instructions and keep all products away from children. Consider purchasing cleaners without VOCs.

Paint, furniture stain, carpet, carpet glue, manufactured countertops, upholstery fabric, and other furnishings also contain chemicals with VOCs. However, it is possible to find VOC-free alternatives for all if them. Buying used furniture is often better because they have already off-gassed their VOCs.

In basements or your chemical storage areas seal cracks, ventilate, and properly store all chemicals where they will not spill.

Carbon Monoxide (CO)
As of July 2011, California requires all homes to be equipped with carbon monoxide detectors in living spaces. Fireplaces and leaking chimneys are sources of carbon monoxide. Ventilate rooms that have fireplaces, make certain the flue damper is operational and fully open when in use, and ensure the chimney is properly sealed.
Combustion heating and cooling appliances such as heating, ventilation, and air conditioning units, gasoline-powered heaters, and other appliances are sources of carbon monoxide as well. Properly install, use, and maintain fuel-burning appliances. To help prevent carbon monoxide exposure, make sure appliances such as gas stoves and fireplaces vent to the outside whenever possible and that all appliances are properly installed, used, and maintained.

Radon
Radon is the leading cause of lung cancer among non-smokers in the U.S. It is a naturally occurring radioactive gas that can enter a home through cracks and openings in floors and walls that are in contact with the ground. Testing your home is simple and inexpensive. Learn more

- Existing Homes: Test for radon — testing is the only way to know if radon is in your home. Do-it-yourself test kits are convenient and accessible, or you may choose to have a professional test your home. If the test result indicates your radon level is too high, a qualified radon service professional can install a radon mitigation system.
      
- New Construction: Radon-resistant new construction (RRNC) draws radon from the soil and vents it through a pipe to the roof, preventing its entry into the house. This technique uses common materials and building skills. RRNC costs less than retrofitting a similar radon reduction system after the house is finished. New home buyers should ask their build to include RRNC features. All new homes, even new RRNC ones, should be tested for radon.


(source: US Environmental Protection Agency)