A Guide to Measuring Pollutants as per WHO Standards: Take Control of Your Indoor Air Quality
In this article we will first explain the different pollutants covered by the World Health Organisation guidelines and then show how you can easily measure the air quality at your home or workplace.
Indoor air quality (IAQ) is an often-overlooked factor in our overall health and wellbeing. Did you know that indoor air can be two to five times more polluted than outdoor air, even in urban areas? The World Health Organization (WHO) explains that ‘clean air is fundamental to health’ and has developed guidelines to help individuals, organizations, and governments understand and improve indoor air quality.
As licensed architects with a passion for healthy building design, we are committed to increasing awareness of these matters and to helping everyone breathe clean air and feel their best.
In this article, we will explore the importance of indoor air quality and its impact on our health, provide an introduction to the WHO guidelines, and discuss additional topics related to indoor air quality that you need to know. We will also touch upon how you might measure your air quality at home in an affordable way.
Understanding the WHO Indoor Air Quality Guidelines
Indoor air quality has a significant impact on our health, and it is important to understand how it’s measured and regulated. The World Health Organization (WHO) has established guidelines for indoor air quality to help countries and individuals enjoy clean and healthy air.
The WHO Indoor Air Quality Guidelines are a set of recommendations for reducing the health risks associated with indoor air pollution. These guidelines provide a framework for measuring and controlling pollutants in indoor environments, including homes, schools, and workplaces.
The pollutants that are tested and measured under the guidelines include particulate matter (PM), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), ozone (O3), and volatile organic compounds (VOCs), among others. These pollutants can be emitted from sources such as cooking appliances, tobacco smoke, cleaning products, and building materials.
Poor indoor air quality can lead to a wide range of health problems, including respiratory diseases, allergies, and even cancer. Children, pregnant women, and the elderly are particularly vulnerable to the health effects of indoor air pollution.
To help mitigate these risks, the WHO has established recommended limits for various pollutants under their guidelines. The current Air Quality Guidelines (AQG) come from two different reports (2010 & 2021, linked to below) and are as follows:
- Small particles PM2.5 should not exceed 5 micrograms/m3 (annual average). This applies to both, indoor and outdoor air (2021).
- Large particles PM10 should not exceed 15 micrograms/m3 (annual average). Indoor and outdoor air (2021).
- Ozone O3 should not exceed 60 micrograms/m3 during peak seasons. Indoor and outdoor air (2021).
- Nitrogen Dioxide NO2 levels should not exceed 10 micrograms/m3 (annual average). Indoor and outdoor air (2021).
- Sulfur Dioxide SO2 levels should not exceed 40 micrograms/m3 (during 24h). Applies to both indoor and outdoor air (2021).
- Carbon Monoxide CO levels should not exceed 4 micrograms/m3 (during 24h). Indoor and outdoor air (2021).
- Benzene (VOC): There is no safe level, avoid all sources. Indoor air guideline only (2010).
- Formaldehyde (VOC): 0.1 mg/m3 maximum exposure in any 30-minute period. Indoor air quality guideline only (2010).
- Naphthalene (VOC): 0.01 mg/m3 (annual average). Indoor air quality guidance only (2010).
- PAHs (polycyclic aromatic hydrocarbons): “No threshold can be determined and all indoor exposures are considered
relevant to health” (2010). These include toluene and benzo[a]
pyrene (B[a]P), among others. - Radon: WHO do not establish a safe ‘boundary’ but recommend the establishment of National Reference levels of acceptable risk for each country and mention 100 Bq/m3 as one possible threshold. The health risks are heightened in current and ex-smokers. Applies to indoor environments only (2010).
- Trichloroethylene (TCE, VOC): No specific threshold set but the report advises how the cancer risk from this substance can be calculated. Guidance applies to indoor air only (2010).
- Tetrachloroethylene (VOC): Recommended guideline for yearly exposure: 0.25 mg/m3. Indoor guidance only (2010).
WHO explain in their report: “WHO Global Air Quality Guidelines (2021)” that these are the levels above which there is clear evidence of negative health consequences. The report can be downloaded for free here: https://www.who.int/publications/i/item/9789240034228
The indoor air quality guidelines are set out by the World Health Organization in: “WHO Guidelines for Indoor Air Quality: Selected Pollutants (2010)”: https://www.who.int/publications/i/item/9789289002134
Please refer to the reports for more details, including short-term exposure limits and good practice statements about other air pollutants, etc. Note that the information in this article has been simplified for readability.
You may also be interested in the following reports:
- WHO guidelines for indoor air quality: dampness and mould: https://www.who.int/publications/i/item/9789289041683
- WHO Guidelines for indoor air quality: Household fuel combustion… (2014): https://www.who.int/publications/i/item/WHO-FWC-IHE-14-01
In addition to these official guidelines, there are other air pollutants that should be considered, including other NOx gases, black carbon, sand and dust storms, additional Volatile Organic Compounds (VOCs, such as acetaldehyde, acrylonitrile and caprolactam), semi-volatile organic compounds (SVOCs), ultrafine particles (UFP), mould, viruses and bacteria, etc. It is outside the scope of this article to discuss these but if you would like further information you can send your query across to us.
In the next section, we’ll explore how indoor air quality standards have evolved over time, and we’ll discuss alternative guidelines that exist outside those of the World Health Organization.
Other Indoor Air Quality Guidelines
When it comes to indoor air quality, there are several guidelines and regulations that exist beyond the WHO standards. While WHO is widely recognized as the international authority on air quality, many countries and organizations do have their own standards in place which are typically less strict. In addition, guidance from other specialist organisations exist, e.g. for reasons of building certification, policy making, engineering or educating the public. In this chapter, we’ll take a look at some examples of these.
One of the most commonly known guidelines are those of the Environmental Protection Agency (EPA). These are specific to the United States. While the EPA guidelines are not as comprehensive as the WHO ones, they still offer an important benchmark for air quality in the U.S.
Other important organisations and publications recognised for their work on advising on improved air quality include:
- The EU Ambient Air Quality Directives (AAQDs)
- UK Department for Environment, Food and Rural Affairs (DEFRA)
- NABERS — National Australian Built Environment Rating System
- The International WELL Building Institute: The WELL Building Standard
- LEED — Leadership in Energy and Environmental Design
- BREEAM — Building Research Establishment Environmental Assessment Method
- CIBSE —Chartered Institution of Building Services Engineers (UK), published guidance and codes
- REHVA — Representatives of European Heating and Ventilation Associations
- ASHRAE — The American Society of Heating, Refrigerating and Air-Conditioning Engineers, published standards
- California’s ‘South Coast Air Quality Management’ (SCAQM)
- California Air Resources Board (CARB)
- U.S. Centres for Disease Control and Prevention (US CDC)
Alternative guidelines can offer a more localized perspective on air quality, taking into account regional factors and pollution sources. However, this can also lead to inconsistencies in guidelines and may make it difficult to compare air quality across different regions. Ultimately, it is important to ensure that any guidelines used are comprehensive, science-based, and prioritise public health, while the WHO guidelines provide a good baseline.
How to Test Indoor Air Quality
There are several methods for testing indoor air quality, including professional testing services, DIY air quality test kits, and using air quality monitors. Professional testing services are typically more expensive but can provide a more comprehensive analysis of indoor air quality. DIY air quality test kits are more affordable but may not provide as detailed results. Air quality monitors, like the Laser Egg, are a popular and convenient option for monitoring indoor air quality over time.
Accurate testing is crucial for identifying pollutants in indoor air and determining the best course of action to improve indoor air quality. Poor testing can lead to inaccurate results and a misinterpretation of the quality of indoor air.
Interpreting test results can be difficult, as there are many factors that can impact indoor air quality. It is important to understand the specific pollutants that are being tested for, as well as the recommended limits and potential health effects. Consulting with a professional or doing further research can help in interpreting test results and identifying appropriate steps to improve indoor air quality.
A good option for taking simple air quality measurements at home is the ‘Airthings 2930 Wave Plus’ from Kaiterra. It measures radon and carbon dioxide (CO2), Total Volatile Organic Compounds (TVOC), air pressure, humidity and temperature.
You can view this air quality monitor here (Amazon affiliate link).
Note that carbon dioxide is often included in air quality monitors even though it’s not a harmful gas, but because it provides an indication of the ventilation levels in the room. Therefore CO2 can be used as a proxy measurement — if the CO2 levels are within a recommended range then other pollutants are likely to be low also, because sufficient ventilation will typically help clear all types of pollutants from the room.
The International WELL Building Institute’s current (2023) recommended optimum levels for the above two measurements are as follows:
- Carbon Dioxide CO2: Keep below 750ppm (parts per million). Levels below 800ppm have been shown to reduce Sick Building Syndrome (SBS).
- Total VOC: 500 micrograms/ m3 or lower.
One thing worth noting is that the VOC count on your air quality monitor can be skewed by 100% natural fragrancies in the air, e.g. from natural essential oils and fragrancies from plants, because these emit volatile organic compounds also. Not all VOCs are harmful. Therefore if you have sources of non-toxic natural fragrancies in the room you may prefer to put more emphasis on the CO2 levels and ventilation than monitoring the total VOC too closely. Avoiding chemical substances is also important, however, and some of the lower quality essential oils may have synthetic fragrancies and harmful VOCs within them also.
These are generic recommendations which will be of general help but may not be appropriate for all purposes. Some health conditions or project-specific requirements, for example, may require more detailed monitoring of specific pollutants or different targets for pollutant thresholds. Refer to manufacturer’s data also for accurate and up-to-date information on pollutants measured.
Conclusions
Indoor air quality is one of the many critical factors in maintaining good health, and the WHO guidelines provide a good framework for measuring and limiting harmful pollutants. Keep in mind, however, that other pollutants also exist which have not yet met the strict scientific requirements of the WHO lists.
Maintaining good indoor air quality is vital for our well-being, and UTA Architects can help establish a strategy for your building to achieve this.
Remember to prioritize your health by taking steps to improve indoor air quality today. You can start by opening the windows.
Stay tuned for more information on healthy building design and architecture. Clap, follow and ask questions via comments/ social media.
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