The Differences in Air Quality Regulations Around The World And The Need For A Global Standard

Outdoor air quality is a very important issue for both human health and environmental sustainability, but there is one key challenge to overcome: the topic is highly technical, and raising public awareness has been difficult as a result. 

To complicate matters further, there is a wide variety of air pollutants and each government establishes its own air quality indexes. As a consequence, there is no international air quality standard that allows countries to benchmark their performance and address the topic in collaboration.

Global companies subject to air quality regulations must learn the rules for each country, increasing the cost of compliance. Although the World Health Organization provides a list of guideline values for each pollutant, these are only guidelines and not legally enforced standards. At the end of the day, each country is free to establish its own Air Quality Index (AQI — not to be confused with IAQ for “indoor air quality”).

Limitations of Current Air Quality Indexes

The most evident difference between the AQIs of different countries is the numerical scale used, and you can’t apply a conversion factor because each index is calculated differently. For instance, the USA, India and Singapore all use a scale that ranges from 0 to 500, but the calculation procedure is different and values are not comparable as a result.

AQIs also differ in the importance given to each pollutant, often influenced by political factors. A global air quality standard could follow the guidelines of the World Health Organization (WHO): they have concluded that the six most relevant air pollutants are carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), fine particulate matter (PM2.5), coarse particulate matter (PM10) and sulfur dioxide (SO2).

Another disadvantage of existing AQIs is that pollutant concentrations are averaged over time periods, which means that a drastic spike in air pollution can go unnoticed. When an average value is calculated, high values are offset by lower values occurring in other hours. Short-term spikes in air pollution can only be addressed with live data measurement across many key locations.

Assume that, in an 8-hour period, an air pollutant concentration is 50% above the accepted limit during 2 hours and 30% below the limit for 6 hours. For the 8-hour period, the average pollutant concentration is 90% of the limit value, which may lead to the false conclusion that air quality conditions were acceptable that day. Unfortunately, these average values are used by many countries and agencies.

How to Interpret Pollutant Concentration Values

You will notice that pollutant concentrations are reported as 8-hour values, 24-hour values and other similar time periods. When you come upon these values, consider that the calculation procedure is the following:

1. The pollutant concentration of interest is measured each hour.
2. The value is averaged along with the measured values of the most recent hours. For example, if a pollutant concentration measurement is taken at 3 PM, the 8-hour value would be the result of calculating an average with the most recent measurement (3PM) and the seven previous ones (8AM through 2PM).
3. Since the procedure can be repeated every hour, there are 24 possible 8-hour concentration values each day. Following the example above, a new 8-hour value can be calculated at 4PM considering the values from 9AM through 3PM.

Keep in mind that this is also possible for minutes. For example, the 10-minute concentration value of a pollutant can be calculated by measuring concentration each minute and averaging the 10 most recent values. This practice comes from the research of health organizations, who have linked health issue with pollutant exposure over time. However, they don’t reflect the instantaneous concentration, which is also important.

World Health Organization guideline values

The WHO has established guideline values for the six pollutants considered the most relevant for outdoor air quality. It is important to note these are guidelines, not legally enforced standards strictly speaking. The WHO also establishes a specific value for each pollutant, instead of the aggregated AQI normally used by governments. The following table summarizes the WHO guideline values for the top air pollutants:

Despite their usefulness, these values can be too technical for use by the general public; an aggregated Air Quality Index of international scope can help achieve better results. Although the definition of the numerical scale is arbitrary, a scale from 0 to 100 can be useful given that the public is already familiarized with it – an AQI of 100 means air quality is excellent, and a value of 0 indicates severe conditions with a high risk for your health and even your life.

How Air Quality Indexes Vary By Country

As previously mentioned, each country defines its own Air Quality Index and its calculation procedure. The following table summarises some of the AQIs used around the world.

With so many differences in considered pollutants, calculation procedure and numerical scales, country-specific air quality indexes are useful for subjective comparison at best. It is not possible to match values between two scales.

Air quality is an environmental and health issue of rising importance in the world, which is reflected by many recent events. A common index to simplify international collaboration is necessary.

• In the first five days of 2017, London surpassed its own air pollution record value.
• Beijing has been under “red alert” due to air pollution for periods of 3 days or more. The city spent 2.7 billion US$ to address this issues in 2017.
• Oslo has established temporary bans on the use of diesel vehicles, in order to reduce air pollutant concentrations.

Requirements for an Effective Global Air Quality Index

To be successful, an international AQI must use an aggregated numerical scale that be interpreted quickly by the general public. In addition, it must account for location and short high-pollution events.

• In modern society, people rarely spend an entire day in the same place. Therefore, an average AQI for an entire city does not reflect site-specific conditions.
• As previously explained, average AQI values are too lenient when dealing with drastic air pollution conditions that last for a short time.

Both performance requirements can be delivered with a monitoring system with multiple measurement points across a city, feeding live data to smart platform. Data is then aggregated and processed to calculate the AQI. Governments can use a mobile application to give citizens access, and the reported value can change according to the new data delivered by measurement points, as well as the user’s location.

An AQI with these characteristics would also be much more useful for governments to benchmark performance and collaborate towards air quality improvement. A global AQI would also be beneficial for international business, since companies can adhere to a single air quality scale regardless of location. Finally, a global AQI can be communicated to the public much more easily, raising public awareness.

If governments fail so far to harmonize their regulations, there are private initiatives trying to address the issue. Breezometer is a Foobot partner, and they have proposed the Breezometer Air Quality Index (BAQI) to address the limitations of conventional air quality indexes. The BAQI reflects live data from thousands of measurement points, and uses the scale of 0-100 as it is already familiar among the general public.

What would be an usable and efficient AQI for you? Let us know your thoughts in the comments below.