Microbes share indoor environments as our unseen roommates of seen world. Over 1000% of the time we expose ourselves to these entities. Many times, these animate creatures go unnoticed; however, on occasion they are adversely affecting our health.
Some common and frequently reported microbes of the indoor environment include, but are not limited to, viruses, bacteria, mycoplasma, mold (fungi), yeast, protozoa, etc. It is difficult to predict the types and quantities of microbes sharing closed environments with humans and other animals, although numbers of microbes thrive in our surroundings, including both unicellular and multi-cellular microorganisms.
Studies have shown that growth of these microorganisms is often supported by moisture, darkness, availability of food sources and a favorable temperature ranging from 72º - 80ºF.
Indoor microbes are problematic to certain individuals, especially those who have a weak immunity. Depending upon sensitivity and other factors, these microbes may initiate allergy, infection and diseases. Allergy refers to an accelerated, altered reaction after exposure to a foreign substance by an individual. Infection is a condition where microbes invade the host body system and multiply with production of toxins. A disease due to microorganisms is a health condition that impairs normal functioning and is typically manifested by distinguishing signs and symptoms.
Indoor allergens are biological or chemical agents which usually cause allergenic reactions in susceptible individuals. Some common symptoms of allergenic reactions are sneezing, stuffiness, runny nose, or itchiness in your nose, the roof of your mouth, throat, eyes or ears, watery eyes, rashes and bumps on skin, etc. Allergens may have a biogenic or an a-biogenic source of origin. Some common indoor bio-allergens include bacteria, mold (fungi), dust mites, insects, pet dander and/or other substances along with plant and animal particulates of various natures. The a-biogenic indoor allergenic substances often include gases or particulates originating from building materials, fabrics, glues, paints, solvents, dyes, perfumes and other inorganic or organic particles and matter.
Indoor Infectious Agents:
Viruses, mycoplasma, bacteria, mold (fungi) and protozoa are common infectious entities of biological nature in and around indoor environments. Most of them are microscopic in nature and present in the ambient air, on environmental surfaces and liquid sources. They also dwell on hosts such as infected individuals residing within a closed environment. Infectious agents, such as bacteria, are capable of producing various odors such as human body odor, fruity smells, pungent stink, earthy smells, locker room odor, sour milk-type reek, etc. A healthy individual may acquire infection due to inhalation, contact or ingestion of infectious agents. Infections due to inhalation are common in indoor environments.
For example the bacteria that are growing in humidifiers, heating, air-conditioning and ventilation systems can trigger pneumonia or other respiratory infections after inhalation. Infectious fungi which may be accumulated due to bird droppings can cause Histoplasmosis and Cryptococcus.
Yeast infection is also common in indoor environments. Consumption of contaminated food with Campylobacter, Salmonella, Cryptosporidium, E. coli, Clostridium etc. can cause severe infection (food poisoning). Human contact with mice, rat, etc. droppings can cause Hantavirus infection. Protozoa and other parasites, such as Entamoeba histolytica, Giardia, etc., are capable of causing infection through ingesting or coming into contact with contaminated food, soil or water in the indoor environment. Chemical pollutants of the indoor environment, such as formaldehyde and volatile organic compounds, are important, non-biological infectious agents of indoor environments.
Indoor diseases are commonly caused due to indoor air pollution and other factors of indoor environments. According to a survey published by the World Health Organization in 2000 revealed that 2.7% of the global burden of disease is caused by indoor air pollution.
Indoor diseases are caused by both living as well as nonliving substrates. Some common living things capable of causing diseases are viruses, bacteria, mold (fungi), protozoa and other parasites. Some common diseases acquired due to indoor factors are obstructive pulmonary disease (COPD), Legionnaires' disease, Pontiac fever, cancer (lungs and other), diseases related to the immune system and others. Exotoxin, endotoxin, mycotoxin and other microbiological volatile compounds produced by various microbes are identified as important disease-causing agents of indoor environments.
Indoor chemical and radiological agents are also listed as potential sources for initiating various diseases in individuals.
Prevention and Management of Indoor Environment:
Prevention through management is a good practice in order to appropriately address the health risk associated with indoor microbes. It is essential to have a periodical assessment to avoid the health risk caused by indoor microbes. A routine check-up of bioaerosols from ambient air and environmental surfaces are good options to identify and quantify the indoor microbes. The outcome is also important for a source causation relationship. Initiate a remedial action if a problem is identified. Prevent accumulation of dust and debris on environmental surfaces, perform routine maintenance of filtration systems; avoid standing water and taking caution with animal feces are some important steps to maintain a good, healthy indoor environment. Good record keeping on building management is recommended as an important action to avoid any health associated risks posed by indoor microbes.
Dr. Rajiv Sahay is the Director of EDLab at Pure Air Control Services in Clearwater, Fla, USA