Types of indoor air pollution
Indoor air pollution emanates from many sources, originating from both indoors and outdoors. Gas and respirable particulates in the air are the primary sources that contributes to poor IAQ. In some countries indoor air quality can be worse than outdoor air quality, especially when we consider the amount of time people spend indoors versus outdoors. The following is a summary of three of the main types of indoor air pollution.
Carbon monoxide (CO) is a by-product of the combustion of fossil fuels and is found indoors where gas appliances (e.g. heaters), gas or wood fireplaces/stoves, cigarette and pipe smoke are used. CO is a highly poisonous gas that can be fatal if inhaled in large amounts. Short-term exposure to carbon monoxide (CO) can reduce the oxygen-carrying capacity of the blood, leading to shortness of breath, dizziness and even death. This is especially dangerous for people with heart disease who already have a reduced capacity for carrying oxygenated blood to the heart.
Carbon dioxide (CO2
) is naturally present in the atmosphere and relatively harmless, however it is toxic to humans at higher concentrations. Like CO, CO2
is also by-product of the combustion of fossil fuels that are commonly used for heating and cooking indoors. As part of the breathing cycle humans exhale CO2
(35,000 to 50,000 ppm) that is around 100 times higher than that in outdoor air. Without adequate ventilation to dilute and remove the CO2
being continuously generated by the occupants and appliances, then drowsiness and lethargy can result. Typically the air is described as ‘stale’ when CO2
levels are elevated.
Volatile organic compounds (VOCs) are gases emitted from certain man made solids or liquids and plants. Cleaning and disinfecting products, paints, furnishings are some common sources of VOCs, including a variety of chemicals, some of which may cause short and long-term adverse health effects depending on the level and duration of exposure. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors which is why it is important to monitor VOCs and/or ensure adequate ventilation to remove and dilute VOC levels.
The actual concentrations of these pollutants can also be amplified by other external factors including poor ventilation, humidity, and temperature.
Find out more about indoor air pollution: Why monitor Indoor Air Quality (IAQ)?