The indoor environment becomes a concern when it gets contaminated due to Chemical, Biological and Radiological (CBR) pollutants. The monitoring of indoor environments becomes necessary in order to evaluate and manage the health and hygiene around such polluted area.

This distresses everyone to some extent, but it is particularly harmful to residents around metropolitan areas with large industrial settings, children whose immunity is still developing, the elderly with known medical conditions and of course, people with compromised immune systems.

The  Sources of CBR Pollutants

CBR related issues of the indoor environment may induce due to a number of activities within the building or as a result of outside infiltration or the combination of both. Some common and frequent CBR agents/of the indoor environment is described below:

Chemical Agents: Various chemicals of inorganic and organic nature are listed as common contaminates of indoor environments. The  products of combustion (oil, gas, kerosene, coal, wood, tobacco products and others), building materials and furnishings, insulating materials, household cleaning supplies, heating or air-conditioning ventilation systems, gardening supplies, microbial or biological decomposition or degradation of indoor materials are some of the common and important examples of potential sources of chemical pollutants. Volatile organic compounds, acetone, alcohols, carbon monoxides, carbon dioxides, methane, sulfur compounds, formaldehyde, amines, ozone, xylene, chlorine, and several other metallic and non-metallic acid and base compounds are documented as indoor air contaminants/pollutants.       

Biological Agents: A diversified group of both macro and microorganisms, besides their byproducts (i.e. exotoxins, endotoxins, mycotoxins etc.), are reported as indoor contaminants. These organisms originate from animal, plant and microbial sources. Viruses, mycoplasma, bacteria, protozoa, algae, fungi/mold, cysts, spores, pollen grains, insects, mites, danders, trichomes, hairs, feathers and other particulates of biological origin as well as the byproducts of animal, plant and microbial origin are identified as potential bio-contaminants of indoor environments. These agents can be mesophiles, thermophiles or psychrophiles based on their growth behaviors in relation to the temperature.              

Radiological Agents: The bulk of radiological agents in indoor environments come from the accumulation of radiation from naturally occurring radioactive materials such as uranium, thorium and radon etc. The most significant source of radioactive material in the indoor environment is radon. Radon comes from the decay of radium; a radioactive element naturally found in soil; however, its concentration is variable. Radon in the air can further decay into radioactive polonium, a potentially harmful substance and carcinogen. The buildings around a nuclear facility, power plants operated with radioactive materials, and laboratories dealing with radioactive materials are more vulnerable to radiological contamination.

CBR Pollutants and Health & Hygiene

CBR pollution is a global problem due to its impact on health and hygiene. The potential risk of CBR contamination is not only linked to short-term exposure with acute symptoms, but can also lead to chronic health conditions from long-term exposure. The results of CBR pollution exposure can be as simple as minor skin or eye irritation to a more complex chronic respiratory disease, cardiovascular issues, or cancer. Some of these conditions can be treated with the supervision of medical professionals; however, in complex situations hospitalization is required, as some cases may be fatal.         

According to a report by the World Bank (1994), a significant loss of life was noticed in developing countries due to indoor air quality. This is mainly linked to burning of wood or coal without proper ventilation. The US EPA Indoor Air Facts No.4 (Air and Radiation 6609 J, R& D (MD-56), February 1991) emphasizes the role of CBR in “Sick Building Syndrome.” In 2009, the WHO guidelines for indoor air quality summarized: “sufficient epidemiological evidence is available from studies conducted in different countries and under different climatic condition to show that the occupants of damp or mouldy buildings, both houses and public buildings, are at increased risk of respiratory symptoms, respiratory infections and exacerbation of asthma.” In a January 2005 news release, the U.S. Surgeon General, Richard H. Carmona, noted that radon is the second leading cause of lung cancer in the United States, with more than 20,000 Americans dying each year from radon-related lung cancer. Only smoking causes more lung cancer related deaths and smokers exposed to radon are at an even higher risk than nonsmokers.

Monitoring and Management of CBR Pollutants

Periodical environmental monitoring is essential to the identification and management of CBR pollutants in indoor environments. In recent years, a number of technologies have become available to detect the presence of various chemical, biological and radiological contaminants. Simple “do-it-your-self” screen test kits are useful in the initial identification of CBR contaminants. Diagnostics for CBR contaminants start with the collection of the environmental samples, documentation of the complaints and symptoms of a building. Environmental samples are collected by sampling air, surface and liquids.  These are then sent to a qualified environmental laboratory to be analyzed. After the identification of the contaminant/s, a detailed and cost effective investigation can be initiated on a professional level. Depending upon the findings, an appropriate control measure can be hypothesized.  Remediation can be initiated should it require addressing the associated problems, if any. 

For newer construction and existing buildings, CBR contamination related issues can efficiently and effectively be managed by drawing some attention. The following factors may be considered in the new construction of a building which can help to mitigate the risks of CBR contamination:

1. A tight building envelope

2. Installation of ventilation at relatively higher levels on building

3. Efficient designing of heating air conditioning ventilation system (HVAC)

4. Physical security of HVAC

5. Periodical monitoring of HVAC control system

6. Routine house keeping schedule

However, in existing buildings an appropriate modification in terms of the above mentioned factors is helpful. The United States Green Building Council initiated a program known as LEED (Leadership in Energy and Environmental Design) for commissioning of new and existing building which can also be helpful in the management of CBR contamination control.


Dr. Rajiv R. Sahay is a Certified Indoor Air Quality Professional (CIAQP) and Laboratory Director at the Environmental Diagnostics Laboratory (EDLab) at Pure Air Control Services Inc. in Clearwater, Florida, USA.