The WHO indoor air quality (IAQ) standards and guidelines define a number of potentially hazardous organic and inorganic substances that can have harmful health effects in homes at high concentrations or after long periods of exposure. The WHO has identified three main groups of indoor pollutants that are particularly damaging to our environmental health: biological indoor pollutants, such as dampness and mold; specific pollutants from chemical pollution; and pollutants from the combustion of indoor fuels. An ideal way to keep track of these harmful organic and inorganic substances, such as carbon monoxide, is to install an indoor air quality monitor, which can alert you when your health is at risk.
What are the threshold limit values for the main indoor pollutants
Poor indoor air quality can come from several sources found in homes, commercial buildings and other workplaces. According to the WHO, biological pollutants can come from hundreds of different types of bacteria, molds and fungi when there is enough moisture in the atmosphere. Indoor chemical pollutants have more diverse origins and are present in our homes as VOCs emitted by the products we buy. The WHO has highlighted eight specific chemical pollutants that have a negative effect on our air quality, according to 50 experts:
- Benzene
- Threshold limit value: 0.1 ppm
- Carbon monoxide (CO)
- Threshold limit value: 35 ppm
- Formaldehyde
- Threshold limit value: between 0.1 and 0.3 ppm
- Nitrogen dioxide (NO2)
- Threshold limit value: 3 ppm
- Naphthalene
- Threshold limit value: 10 ppm
- Polycyclic aromatic hydrocarbons (PAHs)
- Threshold limit value: may vary depending on the chemical.
- Radon
- Threshold limit value: no evidence of a safe threshold.
- Tetrachloroethylene and trichloroethylene
- Threshold limit value: between 25 and 100 ppm
Another hazardous group also worth mentioning is PM2.5, which according to the WHO has two threshold limit values: an annual mean of 10 μg/m3 and a 24-hour mean of 25 μg/m3.
It is important to note that indoor air quality can also be affected by outdoor pollutants, such as sulfur dioxide, typically found in urban areas due to combustion from road vehicles. In addition, the WHO has also pointed out that exposure to second-hand smoke (environmental tobacco smoke) is one of the most significant and widespread sources of poor indoor air quality.
What effects can they have on our health?
Since people spend a lot of time indoors at home or at work, it is important to consider the health risks associated with poor air quality. Exposure to poor indoor air quality can have particularly harmful effects on the respiratory health of the young and the elderly, as well as those with chronic cardiovascular and/or respiratory diseases.
Indoor air contamination has been linked to a number of respiratory symptoms, such as those associated with asthma, chronic obstructive pulmonary disease and rhinitis, as well as respiratory infections. To a lesser extent, there is also evidence suggesting that exposure to indoor air contaminants can also cause hypersensitivity pneumonitis and pulmonary tuberculosis.
Many of the VOCs commonly found in homes are also considered carcinogenic, such as formaldehyde.
How can poor air quality be reduced?
Good ventilation is essential to remove hazardous contaminants from indoor air. The simplest way for people to limit their exposure to poor indoor air quality is to open their windows; however, ventilation systems can also be used to purify the air. That said, ventilation can sometimes be less effective due to poorly placed vents, low air volumes, high levels of recirculation and/or a lack of maintenance. It is therefore important to regularly assess the effectiveness of a ventilation system. It is also worth noting that energy efficiency measures have both positive and negative effects on air quality, mainly by making buildings more airtight. It should therefore not be assumed that energy-efficient buildings provide cleaner air.
An ideal way to evaluate indoor air quality is to carry out an exposure assessment. This makes it possible to estimate or measure how often and for how long people are exposed to a contaminant. By understanding how frequently we are exposed to harmful contaminants and where they are found, steps can be taken to contain their impact on people's health.
Understanding the dangers of contaminated indoor air
Studying the WHO guidelines for indoor air quality can promote better living and working environments. In addition, it is also beneficial for people to develop an understanding of the following:
- What air pollution particle size is and how it can contribute to health problems.
- The different characteristics of semi-volatile organic compounds (SVOCs), a subcategory of VOCs. Knowing this can inform people on how to improve their environmental health by knowing how to avoid them.
- How to reduce particulate pollution, such as nitrogen dioxide and carbon dioxide, as well as other volatile organic compounds.
Sources
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