Why Looking Beyond an Air Quality Index Matters

Countries often interpret the same physical air quality measurement differently when communicating it to their citizens. That’s okay, but sometimes talking in terms of actual physical measurements can make things a lot clearer.

Air quality is complicated: there are many different types of pollutants measured in several non-intuitive sounding units associated with varying thresholds of safety (I mean, what the heck does a microgram per cubic meter look like, let alone feel like to breathe?). It can get confusing!

So for a while now, many entities that monitor air quality — most often environmental and health ministries of governments around the world — use systems that simplify air quality information in order to easily communicate to the public. These simplified systems go by many names, like ‘air quality index,’ ‘pollutant standards index,’ or ‘air pollution index,’ for example, but basically they all take measurements of one or more pollutants and convert them to a simple, unitless number that falls on a color-based scale indicating the health concern of the air (e.g. green = ‘good’ or red = ‘unhealthy’) and possible actions to take based on that scale.

These systems are effective at what they are designed to do: simply communicate complicated air quality information in one easy to interpret, color-coded number to a typically national-level public. These systems vary government to government (or even within the national level), and that’s where the confusion can set in.

Before getting to that though, you might wonder: Why hasn’t the world converged on one system to qualify air quality? Part of it has to do with the science; it’s not exact. For example, there’s not a precise PM2.5 level that is associated with Outcome X or Symptom Y for the general or even a specific population. And this is especially true for places experiencing the world’s most severe air pollution, where we still don’t have a fine-tuned understanding of what the health impacts are due to fewer studies available compared to less polluted places.

And there’s also behavioral messaging in the context of a given place’s air pollution levels. If every day is a ‘red alert’ day in one place, the alert loses its effectiveness and people will disregard it — especially if the general public in a given location has gone years going about everyday business experiencing similar air quality. Some places tie their systems to what they estimate air quality could be given their lowest feasible pollutant emission rates. So, bottom line: it makes sense for air quality messaging to have a local context.

But at the end of the day, scientists, journalists, app developers, and many in the general public working at international, regional, national, and local levels also need actual physical data to advance the fight against air pollution in addition to an air quality index — and the more real-time the data, the better. It’s often the case physical data are not reported alongside the simplified air quality index values shared publicly in real-time. To back-calculate out the physical values is often problematic, even when trying to do so from information provided by some of the world’s most sophisticated air quality monitoring programs. Often the exact algorithm to convert from a real-time air quality index-type measurement to the physical concentration is buried on websites, if actually clearly articulated at all, or requires technical expertise to work around.

Yet, sharing the physical values of pollutants alongside air quality index-type values is powerful, especially as air pollution becomes viewed as more and more of a transnational issue, as scientists, journalists, or app developers both inside and outside of a country want to understand and contribute research, tools, and analyses, and as people live and travel in multiple countries during a single lifetime.

At OpenAQ, we think air quality index-like values have an important place in simply communicating air quality data at local levels, but we also feel there is tremendous — often overlooked — value in sharing physical air quality data in real-time alongside with it. That is why we’re building an open standardized system that aggregates the world’s real-time physical air quality data; we think it’s the necessary scientific, transparent and universal foundation to empower people all over the world to fight air pollution — together.

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