UR Uday Kumar, MD, Amps Facilities Management Services Pvt Ltd explains how understanding and controlling common pollutants indoors can help reduce the risk of indoor health concerns.
Indoor Air Quality (IAQ) refers to air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. Health effects from indoor air pollutants may be experienced soon after exposure or, possibly, years later.
Immediate Effects
Some health effects may show up shortly after a single exposure or repeated exposures to a pollutant. These include irritation of the eyes, nose, and throat, headaches, dizziness, and fatigue. Such immediate effects are usually short-term and treatable. Sometimes the treatment is simply eliminating the person’s exposure to the source of the pollution, if it can be identified. Soon after exposure to some indoor air pollutants, symptoms of some diseases such as asthma may show up, be aggravated or worsened.
The likelihood of immediate reactions to indoor air pollutants depends on several factors including age and pre-existing medical conditions. In some cases, whether a person reacts to a pollutant depends on individual sensitivity, which varies tremendously from person to person. Some people can become sensitized to biological or chemical pollutants after repeated or high level exposures.
Long-Term Effects
Other health effects may show up either years after exposure has occurred or only after long or repeated periods of exposure. These effects, which include some respiratory diseases, heart disease and cancer, can be severely debilitating or fatal. It is prudent to try to improve the indoor air quality in your home even if symptoms are not noticeable.
Primary Causes of Indoor Air Problems
Sources that release gases or particles into the air are the primary cause of indoor air quality problems. Inadequate ventilation can increase pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources and by not carrying indoor air pollutants out of the area. High temperature and humidity levels can also increase concentrations of some pollutants.
Pollutant Sources
There are many sources of indoor air pollution. These can include:
• Fuel-burning combustion appliances
• Tobacco products
• Building materials and furnishings as diverse as:
o Deteriorated asbestos-containing insulation
o Newly installed flooring, upholstery or carpet
o Cabinetry or furniture made of certain pressed wood products
• Products for household cleaning and maintenance, personal care, or hobbies
• Central heating and cooling systems and humidification devices
• Excess moisture
• Outdoor sources such as:
o Radon
o Pesticides
o Outdoor air pollution
The relative importance of any single source depends on how much of a given pollutant it emits and how hazardous those emissions are. In some cases, factors such as how old the source is and whether it is properly maintained are significant. For example, an improperly adjusted gas stove can emit significantly more carbon monoxide than one that is properly adjusted.
Some sources, like building materials, furnishings and products like air fresheners, can release pollutants more or less continuously. Other sources, related to activities like smoking, cleaning, redecorating or doing hobbies release pollutants intermittently. Unvented or malfunctioning appliances or improperly used products can release higher and sometimes dangerous levels of pollutants indoors.
Pollutant concentrations can remain in the air for long periods after some activities.
Inadequate Ventilation
If too little outdoor air enters indoors, pollutants can accumulate to levels that can pose health and comfort problems. Unless buildings are built with special mechanical means of ventilation, those designed and constructed to minimize the amount of outdoor air that can “leak” in and out may have higher indoor pollutant levels.
How Outdoor Air Enters a Building
Outdoor air can enter and leave a building by: infiltration, natural ventilation, and mechanical ventilation. In a process known as infiltration, outdoor air flows into buildings through openings, joints, and cracks in walls, floors, and ceilings, and around windows and doors. In natural ventilation, air moves through opened windows and doors. Air movement associated with infiltration and natural ventilation is caused by air temperature differences between indoors and outdoors and by wind.
Finally, there are a number of mechanical ventilation devices, from outdoor-vented fans that intermittently remove air from a single room, such as bathrooms and kitchen, to air handling systems that use fans and duct work to continuously remove indoor air and distribute filtered and conditioned outdoor air to strategic points throughout the house. The rate at which outdoor air replaces indoor air is described as the air exchange rate. When there is little infiltration, natural ventilation, or mechanical ventilation, the air exchange rate is low and pollutant levels can increase.