Most people are surprised when they first hear this statistic: indoor air can be 100 times more polluted than outdoor air. The reason for this is because, in many cases, outdoor air has more freedom. For example, a pesticide sprayed outdoors isn’t something where you’d say, “Here, take a whiff.” Yet that outdoor pesticide is integrated with lots of other fresh air that reduces the harm it can cause at closer range. On the other hand, the fumes from a pesticide sprayed indoors – especially in a home that’s tightly sealed for winter – have no place to go. So they mix with the other air in your home and become a part of your breathing.

The toxins in your indoor air come from a variety of sources, including:

Volatile Organic Compounds (VOCs) – Many organic chemicals are used as ingredients in household products. As they vaporize and become gases at normal room temperature, they are known as VOCs. Common items that release VOCs include paints, varnishes, cleaning supplies, furniture and building supplies, pesticides, office equipment, permanent markers, hobby products and more. Fumes can be released from these products when they’re in use or when they’re stored.

Pesticides – Any type of pest-control product can emit toxins in your home. The health effects vary with the product, ranging from irritation to eyes, nose and throat to more severe consequences on the central nervous system and kidneys.

Carbon Monoxide – Carbon monoxide (CO) is a leading cause of poisoning deaths that are often attributed to heating and cooking equipment. These sources include gas-fueled space heaters, gas-fueled furnaces, charcoal grills, gas-fueled ranges, portable kerosene heaters and wood stoves.

Biological Pollutants – Biological pollutants have a wide range of sources, including mold, mildew, bacteria, viruses, animal dander, dust, saliva, pollen, dust mites and cockroach droppings. Mold and mildew can release toxins in the air that can cause illness. Those prone to allergies and asthma commonly react to many of the other biological pollutants.

Radon – Radon is a colorless, odorless gas that occurs naturally in soil and rock and is a decay product of uranium. It can seep into your home through openings such as pipes, cracks in the foundation, sumps and drains.