Indoor Air Pollutants List

Indoor Air pollutants Overview

The typical indoor air environment is “contaminated” with tiny substances, known as indoor air pollutants, that are usually unseen  by  the  naked  eye,  typically  measured  in  microns 3(μ).  At  natural  levels,  those substances are in quantities that typically would not harm the occupant, but when their concentrations increase to a certain extent they can become damaging to health in various ways. Indoor air pollution describes the existence and concentration of those substances in the indoor environment.

Different categorizations exist for distinguishing indoor air pollutants. One typical one used by EPA is distinguishing them into particulate and gaseous pollutants (Environmental Protection Agency [EPA], 2012). The problem with that broad categorization is that many pollutant sources share characteristics from both categories; such is the environmental tobacco smoke (ETS) that produces both gaseous pollutants and particulate matter. For that reason, distinguishing them in more specific subcategories is more accurate.

Indoor Air pollutants List

An alternative categorization of the indoor air pollutants and their most important substances, based on EPA reports is the following:

Particulate Matter (PM): A mixture of air-borne solid particles and liquid droplets

  • Coarse Particles(PMcoarse): PM with a diameter between 2.5 and 10 microns that is inhalable but usually reaches only the upper respiratory tract
  • Fine Particles(PM2.5): PM with a diameter equal or below 2.5 microns that has the potential to penetrate deeply into the lungs

Biological Pollutants: Living microorganisms or their residues that contaminate the air

  • Pollen: Highly allergenic to humans coarse powder produced by flowering plants
  • Pathogenic bacteria: Coarse or fine in size malicious single cell organisms causing localized infections that can be treated with antibiotics
  • VirusesVery  fine  structures requiring  a  living  host  to  reproduce, causing systemic infections that have no absolute cure
  • Mold:  Coarse  or  fine  in  size,  type  of  fungus  that  grows  in  mostly  humid environments digesting plant materials
  • Pet allergens: Coarse or larger highly allergenic particles such as skin flakes, urines, saliva, feces, and hair that are shed from domestic animals
  • Parasites such as dust mites: Parasitic organisms who leave large particulate by–products that are highly allergenic to humans

Combustion Products: Fine particulates and gaseous pollutants that usually originate from the combustion of fossil fuels in indoor environments

  • Carbon monoxide: An ultra-fine in size, colorless, odorless, tasteless, toxic in high doses gas that usually originates from incomplete fuel combustion.
  • Nitrogen oxides (NO & NO2): Ultra-fine in size, reddish-brown in color, highly reactive and toxic gasses released from combustion processes.
  • Respirable Particles: Fine particles that are becoming airborne through fossil fuel combustion processes and act as carrying agents of other contaminants.

Household chemicals: Organic chemicals found in a variety of household products such as cleaning agents and paints that emit ultra-fine gasses, known as Volatile Organic compounds (VOCs)

  • Formaldehyde: A very toxic, colorless with a pungent, irritating smell organic gas that  is  emitted  by  many household    products, building  materials and unvented fuel-burning appliances
  • Benzene:  A  colorless  liquid  with  a  gasoline-like  odor  producing  high  VOC emissions coming mostly from vehicle fuel and coal combustion processes.
  • Perchloroethylene: A colorless liquid used frequently in dry cleaning of fabrics that has strong VOC emissions with a distinct sweet smell.
  • Methylene  Chloride:  A  colorless,  volatile  liquid  with  a  moderately  sweet aroma that is widely used as a solvent.

Pesticides: A broad category of chemical and toxic to man products that function as pest repellents, plant regulators or nutrient stabilizers.

  • Active   ingredients   such   as   Paradichlorobenzene:   The   pesticide’s   toxic substance that is biologically active and acting as the catalyst to reach the pesticide’s functions
  • Inert ingredients such as   Xylenes: The pesticide’s substance that does not have a toxic effect on the species the pesticide is meant to combat, but that does not exclude detrimental effects on other species including humans

Minerals: Minerals are inorganic and organic substances that originate in the earth and cannot be made in the human body

  • Asbestos: A carcinogenic mineral with very fine fibers that has been used commonly in a variety of building construction materials  in older homes
  • Lead (Pb): A highly poisonous metal, found in the air in very fine particles and that is commonly used in paint products

Other Pollutants

  • Environmental Tobacco Smoke (ETS): Passive exposure to fine particulates and gaseous pollutants coming from cigarettes, cigars, or pipes.
  • Radon:  A  colorless,  odorless,  tasteless  radioactive  gas  that  permeate  the house from the ground and has long-term carcinogenic properties

Sources for the List

A list of all the afore-mentioned indoor air pollutants, along with their associated health issues, potential  sources  and  suggested  preventive/  eliminating  measures  against  them  are displayed in detail on table 2. The list was mostly compiled by various impact studies from EPA and other independent organizations such as the health departments of New York and California and the American Lung Association.

Disclaimers for the List

Table 2 is intended to be used as a general informative source for the typical homeowner to knowing better the contaminants that he is facing in his indoor environment. In the first column there is a detailed list of potential health symptoms that occur in excessive concentrations of their corresponding indoor air pollutants. The word excessive here in not used lightly, since all homes will be found to feature all the presented pollutants but usually in concentrations that are not considered statistically significant to cause any health issues. That have been said, the sensitivity to a specific pollutant varies from person to person, and therefore awareness and precaution are crucial into identifying in a timely manner when symptoms related to IAQ are evident.

Regarding the control techniques suggested on the table, one should be aware that their corresponding suggestions and instructions are meant to be used only as a reference point and not as an exhaustive guide to provide all the procedures needed to engage in a specific contaminant‘s source control. Instead those suggestions are there to give general knowledge and awareness, and to provoke the homeowner to do his personal research in order to acquire as much insight as possible regarding the pollutant that he has to face

Nonetheless, table 2 can provide some good basic knowledge regarding health symptoms, source and control suggestions and it’s advised to be viewed frequently, especially when applying the IAQ Master Plan strategy that will be presented at part 3 of this paper.


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