What Are The World Health Organization Guidelines for Indoor Air Quality?

The World Health Organization is an agency of the United Nations that focuses on public health from an international perspective. The WHO is among the leading organizations that recognizes indoor air pollution as a major health concern for most countries. Since it’s more concentrated, indoor air pollution is often at higher levels than outdoor air pollution. This presents serious health risks not just in homes but daycare centers, schools, offices, public buildings, healthcare facilities and so forth. In order to aid residents and organizations improve the air in their indoor environments, the WHO has developed and maintains indoor air quality guidelines, which are currently presented across four publications.

Four Sets of WHO IAQ Guidelines

The core publication for the WHO guidelines is titled “WHO Air Quality Guidelines for Particulate Matter, Ozone, Nitrogen Dioxide and Sulfur Dioxide.” It was originally published in 1987, and the WHO published a second edition in 2005. All guidelines are updated on an annual basis, and subsequent editions reflect major changes to the structure and other aspects of a guide. In 2009, the WHO published “Dampness and Mould,” which focuses specifically on microbes that are byproducts of mold, fungi and bacteria. In 2010, “Selected Pollutants” was published with a focus on gases and chemicals that may occur naturally but are often inadvertently introduced to a living area. Most recently, in 2014, the WHO expanded its guidelines with “Household Fuel Combustion,” which focuses on residential cooking, heating and lighting.

Particulate Matter

The WHO now estimates that two million premature deaths occur annually throughout the world due to poor indoor air quality. Particulate matter is a leading cause of air quality degradation and can lead to respiratory inflammation and cause changes to lung function. The guide focuses on two types of particulate matter: PM10, which measures 10 microns or less, and PM2.5, which measures 2.5 microns or less. PM2.5 is also known as fine particular matter. PM10 includes dust, pollen and bacteria fragments while PM2.5 includes the byproducts of wood, gas and oil fuel combustion. The WHO indicates the danger levels for both kinds via averages for both 24-hour and 365-day periods.

Ozone, Nitrogen Dioxide and Sulfur Dioxide

Later versions of the WHO guidelines added ozone, nitrogen dioxide and sulfur dioxide alongside particulate matter as the four major causes of degraded indoor air quality. O3, NO2 and SO2 all occur in the atmosphere for both natural and man-made reasons, such as automobile emissions. These pollutants make their way into residences and workplaces and become even more concentrated. As with PM2.5 and PM10, the WHO indicates the danger levels as periodic averages using the metric micrograms per cubic meter of air or ug/m3. The recommended daily averages are higher than the annual average because levels will fluctuate, but a high annual average indicates a more persistent indoor air quality problem.

The Expanded Guidelines

Note that the core WHO guidelines do not cover mitigation. A primary reason for this is that the appropriate mitigation often depends on the pollution levels, environment, climate and so forth. Instead, the World Health Organization focuses on establishing realistic target levels for optimal health and presents the scientific rationale for how those numbers were reached. The additions to the guidelines go into a bit more detail. They cover the appliances and other items in homes and workplaces that introduce pollutants. They also touch on specific health scenarios, such as asthmatics requiring a lower nitrogen dioxide threshold.

Dampness and Mold

This addition to the guidelines focuses on limiting mold levels in homes and other indoor environments. The WHO warns that inhalation of mold spores can compromise the immune system as well as exacerbate symptoms associated with asthma, allergies and other respiratory issues. The presence of mold is not only a health issue in its own right but can intensify the health issues caused by high levels of particulate matter, ozone, nitrogen dioxide and sulfur dioxide. These guidelines extend to mold testing as well and provide recommendations for moisture control and ventilation. Moisture control is key to avoiding mold, but the WHO asserts that optimal ventilation can significantly mitigate the health effects associated with mold. In addition, air filters can trap spores while mold sources are eliminated.

Selected Pollutants

While particulate matter, ozone, nitrogen dioxide and sulfur dioxide are the four main causes of poor indoor air quality, there are many others as well. There are, for instance, dangerous gases and chemicals that have known indoor sources, such as radon, carbon monoxide, benzo[a]pyrene and formaldehyde. This guide is an opportunity for the WHO to go into greater detail on the four main causes and all of these other chemicals and gases that are potentially dangerous. For each substance, the guide covers indoor sources, outdoor sources, health risks, sensitivity and guidelines. The guidelines specify danger levels, best practices for testing and, in some cases, options for mitigation or elimination.

Household Fuel Combustion

The latest addition to the WHO guidelines focuses on clean fuels and technologies for cooking, heating and lighting. An emphasis of this particular publication is warning against the use of coal as a household fuel. Use of coal in the home is quite uncommon in the United States, but it’s still prevalent in other countries, such as China. There are, however, aspects of this guideline that are of interest to Americans since they cover the use of burning wood as a heat source and the use of gas and electric ovens and other appliances. The WHO provides ventilation guidelines, for instance, for gas-burning stoves to avoid excess nitrogen oxide that can trigger asthma symptoms and cause wider health problems as well.

WHO Recommendations

The WHO notes that the primary audience for these guidelines is policymakers rather than homeowners and businesses. However, you can use the pollution level numbers to determine whether your home is in a safe range. The WHO also recommends investigating outdoor pollution levels in your area in order to view your home within context. If PM2.5 levels are higher than normal in your city, you can expect higher levels in your home. In addition, if you live on a busy street, you can expect higher levels of carbon monoxide. The WHO recommends indoor air quality audits for homes and businesses after assessing regular cleaning practices. Poor or irregular cleaning can exacerbate pollution. If, after the audit pollution, levels are higher than desired, steps can be taken, including sealing the home, upgrading the ventilation, upgrading the heating and/or cooling, and adding air purification and dehumidification.

Your Local Indoor Air Quality Experts

Air Max HVAC, Inc has served Burbank and the surrounding areas for 20 years, and we look forward to many more years of high-quality service to come. Indoor air quality is an integral aspect of our trade, and we have an IAQ team that conducts audits, specializes in ventilation and filtration and installs and maintains air purifiers, dehumidifiers, humidifiers and germicidal lights. Our company also offers a full range of installation, maintenance and repair services for home heating and air conditioning, and we perform home energy audits in order to help our clients reduce their energy costs. Call us today to learn more about these services or to schedule an appointment.

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