Indoor Air Pollution: The Unhealthy Ingredients of Air

55% of Americans breathe unhealthy air in their home. Find out what you could be breathing as you are reading this – what types of indoor air pollutants may be in your home, how pollutants affect your health, and how you can address sources of pollutants.

Living in a modern society, you’ll more often than not find yourself spending your time indoors. This isn’t a surprise as we’ve mentioned in a previous post, the average Americans spend over 87% of their time indoors.

This can either be at home, work, or public buildings such as schools, malls, or restaurants. Unfortunately, this means you and your family are constantly exposed to potential indoor pollution. According to the EPA, indoor air can be up to 5 times and in some cases up to 100 times more polluted than outdoor air.

Primary Indoor Air Pollutants and Their Sources

What are some of the most common forms of indoor air pollution that you’ll find in a home? This can vary greatly depending on your geographic location, the type of home you live in, and even the pets around the house. The following chart breaks down the most common pollutants:

Bioaerosols Volatile Organic Compounds (VOCs) Inorganic Pollutants (Gaseous and Particulate)
Characteristics Liquid or solid particles suspended in a gaseous medium Gases released from solid or liquid materials (off-gassing) Non bio-degradable chemical compounds that exist as inorganic gases or particles suspended in the air
Pollutant Size Ranges 0.001 to 100 µm As small as 0.0004 µm  ~ 0.0001 to 100 µm
Pollutant Examples Microorganisms
Bacteria
Fungi
Viruses
Volatile Organic Compounds (VOCs)
Formaldehyde
Benzene
Perchloroethylene
Methylene chloride
Tetrachloroethene
Heptane
Naphthalene
Ethyl acetate
Ozone
Nitrogen Dioxide (NO2)
Carbon Monoxide (CO)
Radon (Rn)
Asbestos
Lead
Organic compounds from microorganisms
Metabolites
Microbial fragments
Small particles of biologic origin
Animal dander
Dust mite allergen
Cockroaches allergen
Pollen

Bioaerosols
These are a wide range of liquid or solid particles suspended in a gaseous medium with wide ranging sizes, from 0.001 micron living microorganisms such as viruses, to larger particles such as pet dander from dogs and cats, or cockroach body parts and droppings. Other common bioaerosols are bacteria, mold spores, and various microbial organisms. Bioaerosols are known to be a primary cause for allergy symptoms and asthma exacerbation.

There are many sources of these pollutants –  pollen from plants, airborne pathogens (viruses, bacteria) transmitted by people and animals, dust and dander from animals, as well as mold spores from damp surfaces. The level of these organic pollutants highly depends upon location and living situation.

An important bioaerosol to point out is mold. Did you know that the occasional water leak in your house can radically degrade the indoor air quality? A study from the Lawrence Berkeley Lab estimates that about 47% of housing units in the United States have harmful exposure to dampness and/or mold. Control humidity and moisture, and pay attention to any building damage (e.g., a leaky roof) to limit the growth of mold in the first place.

Volatile Organic Compounds
These are gases emitted from certain solids or liquids, many of them are from common household chemicals and products such as pesticides (heptane), paints  (benzene), adhesives (tetrachloroethene), and air freshener (naphthalene). Typical household furnishing such as upholstered furniture and carpets often emit formaldehyde. Personal care products such as nail polish, nail polish remover, colognes and perfume frequently emit ethyl acetate.

Because most homes will have multiple sources of indoor air pollution and the effects are cumulative, these pollutants (some of which are carcinogenic) can at times cause or worsen respiratory diseases such as asthma and allergies.

As Bioaerosols, VOCs are a major contributor to indoor air pollution.

Inorganic pollutants (particulate & gaseous)
These constitute a wide range of gaseous and particulate pollutants that are non-biodegradable, a majority of them entering the atmosphere as a result of civilization. Those added in the greatest quantities are Carbon Monoxide (CO), Sulphur dioxide (SO2), Nitrogen Monoxide (NO) and Nitrogen Dioxide (NO2). The primary source of these gases is combustion of fossil fuels in power plants, industrial equipment, and vehicles.

Also, a wide range of building and packaging products have been shown to release inorganic particulates and contaminants into the air. Some of these particles such as Lead and Asbestos are proven carcinogens, some such as Radon are even radioactive.

High indoor concentrations of such particles can result from outdoor pollution sources, choice of building materials, products that we bring in our homes, and even our activities inside. For instance, smoking indoors results in “second-hand smoke”, scientifically known as environmental tobacco smoke (ETS) which is a complex mixture of over 4,000 chemicals, more than 40 of which are known to cause cancer and many of which are strong lung irritants.

Health Effects of Indoor Air Pollution

Indoor air pollution is a growing health issue as recognized by the World Health Organization, the EPA, OSHA, and the American Lung Association. The World Health Organization estimates that it causes 4.3 million deaths around the world. An assessment by the American Lung Association finds about 166 million Americans are at risk from health effects of unhealthy air.

While there has been an emphasis on particulate air pollution caused due to emissions, varied indoor air pollutants have been tied to many adverse impacts on one’s health. While some of the negative health effects are immediate, air pollution has been linked to potentially fatal long-term outcomes such as cancer.

Common Pollutants Negative Health Effects
Bioaerosols Dust mite Strong link to development and exacerbation of allergic rhinitis and asthma
Animal and cockroach allergen
Mold spores Risk factor for the development and increased severity of asthma, causes headache, fever, and allergic rhinitis
Bacteria and viruses Increase chance of transmission and spread of infectious diseases such as measles, TB, chickenpox, influenza, and more
Endotoxins Causes inflammatory and atopic responses, exacerbation of asthmatic individuals
Volatile Organic Compounds (VOCs) Benzene Group 1 carcinogen (leukemia)
Tetrachloroethene Group 2A carcinogen
Naphthalene Group 2B carcinogen
Formaldehyde Breathing difficulties, nosebleeds, and persistent headaches
Ethyl acetate Irritation to the eyes, nose, and throat
Inorganic Pollutants (Particulates and Gaseous) Lead Convulsions, coma, severely damages the nervous systems (kids in particular are very vulnerable)
Asbestos Group 1 carcinogen (fatal lung disease)
Ozone Lung irritant, chest pain, coughing, shortness of breath. Can also exacerbate asthma and impair respiratory functioning
Nitrogen Dioxide Affects the mucosa of your sensory organs, acute/chronic bronchitis, respiratory infections. High level can result in pulmonary edema
Carbon Monoxide Fatigue, impaired vision, headache, dizziness, nausea. Fatal at very high concentrations
Radon Group 1 Carcinogen

A person’s reaction to indoor air pollutants can often mimic colds, allergies, flus, or other illnesses. Common symptoms includes irritation of the eyes, nose, and throat, headaches, dizziness, and fatigue. Asthma, allergies, persistent upper respiratory illness, and fevers can also occur.

Long-term exposure to indoor air pollution can lead to respiratory diseases, heart disease, and cancer. Many of the people who may be exposed to indoor air pollutants for the longest periods of time are often those most susceptible its effects – the young, elderly, and chronically ill.

Solutions to Indoor Air Pollution

Thankfully, there are some actionable steps you can take to address indoor air pollution. There are mainly three actions you can take to reduce or outright eliminate indoor air pollution in the home.

Source Control
This may seem obvious, but the most effective way in improving indoor air quality is to eliminate individual sources of pollution or reducing their emissions.

Some quick examples include:

  • Avoid purchasing products that produce high levels of formaldehyde or other VOCs. When purchasing products like furniture, carpets, mattresses, look out for the “Low VOC” label.
  • Same applies to building materials which are commonly rated for their VOC emissions.
  • Keep humidity levels between 30-50% in a home to reduce dust-mites, which grow in warm and damp environments.
  • Regularly clean the home to help reduce animal danders and pollen.
  • If you are allergic to dust mites, regularly wash your bedsheets, pillow covers, curtains and rugs – preferably in hot water (130F)
  • Use natural cleaning product
  • If you use appliances in your house that use kerosene/gas (such as space heater, stove, water heater, etc), ensure that there are no leaks and your appliances are properly maintained
  • Control smoking indoors by suggesting smokers to step outside to reduce ETS

In short, you should understand where biological contaminants can come from, how certain products you use can contain and emit chemicals, and that they should be used with caution.

Improving Ventilation
Making a habit in cycling and introducing outdoor air into your home is one of the most actionable and cost-effective ways to lower concentration of indoor air pollutants. Good air circulation helps against all form of indoor air contaminants, be it an organic particulate, VOCs or an inorganic contaminant.

Ventilation is also very important when you do activities that increase pollutants in your home (cleaning, painting, cooking, etc.).

Get your HVAC system inspected periodically and ensure that your house meets the requirements for mechanical filtration.

Utilizing Air Cleaners
Air purifiers can help reduce indoor air pollution levels. But there are many different types of air purifiers on the market and understanding the differences can be confusing. See our overview of portable air purifiers. If interested you can have a deeper look at HEPA filters and finally learn about why you should avoid ionizers.

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