HVAC/R Specialists Serving Reading & Berks County

What Are the Most Common Types of Indoor Air Pollution?

Most people might think that air pollutants are exclusive to the outdoors, but they are shocked to learn that they can sometimes find themselves inside and even be caused by you or someone else.

These pollutants pose a threat as they can cause varying health conditions that can present effects immediately or up to years later. Air pollutants will fall into one of four general categories; VOCs, biological pollutants, combustion byproducts, and legacy pollutants. We’ve listed some of the most common indoor air pollutants in these categories to help you identify which, if any, of the air pollutants are present in your home.


For those who don’t know, asbestos is a chemical found in various construction materials such as insulation and roof shingles and can be used as a fire retardant. There are limitations to the production, import, and distribution of asbestos-related materials due to an increased risk of lung cancer, mesothelioma, and other illnesses caused by prolonged asbestos exposure.

Biological pollutants

As the name suggests, biological pollutants originate from living things and can include bacteria, viruses, pet dander, dust, and pollen. Mold and mildew can also be found in locations exposed to excessive moisture, such as a humidifier or an unvented bathroom.

Carbon monoxide

Carbon Monoxide is an odorless, colorless gas that is released when burning fossil fuels and is most commonly found emanating from vehicles, gas heaters, and kerosene lamps. Carbon Monoxide, when inhaled in large amounts, can cause the amount of oxygen in the body to drastically decrease, leading to dizziness, unconsciousness, and in extreme cases, death.

Cookstoves and heaters

Burning wood, charcoal, or other solid fuels inside without proper ventilation can cause an abundance of smoke and fumes and lead to various serious health and lung issues. This method is not the most common practice in the US, though it is still used by billions of people all over the world.


Like asbestos, formaldehyde is another chemical found in many common building materials, cosmetics preservatives, glues, paints, and pesticides. Unlike asbestos, formaldehyde is a chemical compound that’s also a combustion byproduct, meaning it can come from fuel-burning appliances. Short-term effects include eye, nose, throat, and skin irritation; long-term effects can lead to cancer.


Most lead can be found inside a home from burning leaded fuel, and once it enters the body, there are many different reactions and effects. Adults can face potential health problems with their nervous, cardiovascular, and reproductive systems. For children, they face potential behavioral and learning challenges from too much exposure to lead.

Nitrogen Dioxide

This particular gas is a highly reactive byproduct of cars, trucks, and power plants from burning fuels and, when combined with water in the atmosphere, can lead to acid rain. Nitrogen Dioxide can also be harmful to those with preexisting respiratory conditions such as asthma and worsening symptoms such as coughing, wheezing, and trouble breathing.


Pesticides are a chemical concoction that is primarily used to control insects, termites, rodents, and other pests; and can be in the form of disinfectants and insecticides, among other household items. They primarily irritate the eyes, nose, and throat, increase the risk to the central nervous system, and increase the risks of cancer.


Like carbon monoxide, radon is a colorless, odorless gas that’s hard to locate without the proper equipment. Radon is a naturally occurring gas with small trace amounts being normal if detected outside. If detected inside, it is normally due to the gas finding its way through the cracks in a building and can be corrected by proper ventilation. Exposing yourself to radon can vastly increase the risks of lung cancer, as radon is the second leading cause of lung cancer in the US.

Indoor particulate matter

Particulate matter is just a fancy word for particle pollution, which is the abundance of solid particles in the air that cause a range of respiratory and cardiovascular problems. These particles can come from places like construction sites to beaches, making virtually every location a source, but most tend to be chemically induced. Unlike others, these particles can only be seen on a microscopic level and thus require certain tools like the Air Quality Index to keep track of.

Secondhand smoke/Environmental tobacco smoke

Secondhand smoke occurs when tobacco products, like cigarettes, are burned, and individuals passively inhale it. Secondhand smoke can cause heart disease, lung cancer, asthma attacks, and other conditions.

Volatile Organic Compounds (VOCs)

VOCs are gases emitted from various items found in and around your home, including aerosols, cleaners, and paints. The effects of VOCs range from skin, eye, and throat irritation to damage to the internal organs and nervous system.

Wood smoke

Smoke is the mixture of gases and microscopic particles that are released upon burning something, such as wood. Many people still use wood stoves and have fireplaces in their homes and should be aware of the respiratory effects and irritation they could experience coming into contact with smoke.