When you think of the term pollution, outdoor air quality may come to mind first. However, pollutants can also affect indoor air quality, where they can pose serious risks to human health. This article outlines specific indoor contaminants of concern and their potential sources. We’ll also cover some of the health symptoms that can arise from polluted indoor air.


Types of Pollutants that Impact Indoor Air Quality and Human Health

The following are a few indoor air pollutants that can contribute to unhealth

y air quality and potential sources in your home, commercial building, or industrial site.

Particulate Matter (PM)

Particulate Matter (PM) is a class of pollutants characterized by variable and small diameter particles that vary from ultra-fine (PM0.1), fine (PM2.5), and coarse (PM10). PM affects humans when the air particles penetrate the respiratory system via inhalation, increasing the risk of respiratory and cardiovascular diseases, reproductive and central nervous system dysfunctions, and cancer. If a person is exposed to fine dust over an extended period, the immune system can deteriorate rapidly, contributing to health risks.

Potential sources of particulate matter air quality pollution include:

  • Road dust
  • Fossil-fuel combustion
  • Biomass burning
  • Waste incineration
  • Cooking
  • Vehicle emissions
  • Industrial facilities

Gaseous Compounds

Carbon monoxide is one of the most known types of gaseous compounds that can decrease indoor air quality, provoking various health symptoms and even death when breathed in at high levels. Beyond carbon monoxide, other gaseous compounds that can affect your health include nitrogen oxide, ozone, and sulfur dioxide.

Potential sources of gaseous compound air quality pollution include:

  • Fossil fuel combustion
  • Vehicle emission
  • Wood burning
  • Waste incineration
  • Electric utilities
  • Industrial facilities

Heavy Metals

Heavy metals such as lead, cadmium, nickel, and arsenic are other indoor air pollutants that could be lurking in your air. When these compounds are absorbed into the human body, they can lead to direct poisoning or chronic intoxication, depending on the exposure level.

Potential sources of heavy metals air quality pollution include:

  • Metal refineries
  • Battery manufacturing
  • Waste incineration
  • Industrial facilities
  • Leaded fuel
  • Lead-based paint
  • Plumbing materials
  • Aircraft industry
  • Television manufacturing
  • Casting
  • Welding


Polycyclic aromatic hydrocarbons (PAHs) describe a broad class of environmental compounds that can adversely affect indoor air quality. They include organic structures containing the elements carbon, hydrogen, oxygen, nitrogen, and sulfur. These widespread pollutants form during the combustion process, resulting in unhealthy indoor air quality.

Potential sources of PAH air quality pollution include the incomplete combustion of organic material, such as:

  • Biomass and garbage
  • Vehicle emissions
  • Asphalt road fumes
  • Cigarette smoke
  • Grilled or charred meats


Widely used in many household products, volatile organic compounds (VOCs) refer to gasses emitted from solids and liquids that can cause many adverse health effects. The EPA has found some VOCs have levels 2 to 5 times higher inside than outside, significantly affecting indoor air quality and health.

Potential sources of VOC air quality pollution include:

  • Fuel combustion
  • Aircraft emission
  • Household products
  • Chemical solvents
  • Paints
  • Varnishes
  • Cigarette smoke


Semi-volatile organic compounds (SVOCs) are a subgroup of VOCs with a higher molecular weight and boiling temperature. These indoor air quality pollutants can be found in residential and commercial buildings. Whether from gaseous airborne chemicals or surface adsorption, SVOCs can cause many adverse health effects, including endocrine and thyroid disruption, immunotoxicity, reproductive toxicity, and cancer.

Potential sources of SVOC air quality pollution include:

  • Solvents
  • Fragrances
  • Bactericides
  • Antimicrobial agents
  • Flooring
  • Furniture

Health Symptoms Of Poor Air Quality

Depending on the type of pollutant and the duration of exposure, poor air quality can cause a range of adverse effects in humans that can develop into or worsen health conditions, including:

  • Respiratory illnesses, such as asthma, chronic obstructive pulmonary disease (COPD), and lung cancer
  • Cardiovascular diseases, such as heart failure, arrhythmias, and cardiac arrest
  • Central nervous system dysfunctions, such as ADHD, dementia, depression, multiple sclerosis (MS), schizophrenia, neurodevelopment problems
  • Skin conditions, such as pigment spots, wrinkles, acne, atopic dermatitis, and eczema

Experts also believe that air quality pollution affects the geographical distribution of many infectious diseases, even further highlighting its dangers.

As we covered in a recent blog article, now is an especially critical time to check the indoor air quality for potentially harmful pollutants in your home, office, or industrial building. With over 25 years of experience, our indoor air quality (IAQ) team is skilled in providing high-quality and effective air quality services to promote clean air for everyone to enjoy.