Driving air pollution accountability and action via data transparency

Poor air quality is now one of the three main causes of premature morbidity, resulting in nearly 7 million deaths globally in 2022. Moreover, 99% of the world’s population experiences air pollution levels exceeding World Health Organization guidelines, clearly necessitating action to limit our risk. Yet, our ability to mitigate poor air quality and the damage it causes is hampered by a lack of actionable information.

Air pollution comes from a wide variety of sources – from campfires to cargo ships – and it is difficult to monitor effectively. Due to the dynamic nature of our atmosphere, the distribution of pollutants is constantly evolving. Pollutants generated from agricultural practices in rural regions can be transported to urban areas, and emissions generated from cars on busy roadways can travel far from the original source. Additionally, the exact concentration and dispersion of pollutants changes over time due to chemical reactions in the atmosphere.

The complex nature of air pollution suggests meaningful action plans cannot be developed without better monitoring. For example, restricting automobile traffic in a major city may not have the intended mitigating effect if more agricultural chemical by-products transit over the city. Additionally, measuring air pollution in spot locations paints an incomplete picture. Without understanding air pollution sources, we may put in place policies that mitigate the wrong things. We need complete information, as close to everywhere and at all times as possible, to make informed decisions.

Some of the key pollutants to track include particulate matter at 2.5 and 10 microns (PM2.5 and PM10), Ozone, Nitrogen oxides (NOx), and Sulphur oxides (SOx). These must be monitored with reasonable temporal and spatial resolution for us to understand sources and changes over time, and to provide the data for models to predict future conditions. Robust, objective data drives transparency, enables accountability, and is fundamental to trigger effective action by national governments, cities, industries, and individual companies.

Existing information is generated by ground-, air- and space-based measurements, and air quality models. Ground-based instruments provide instantaneous data where it is most relevant for human health, but they only provide hyper-local information and may lead to the misallocation of resources or misrepresentation of reality based on their distribution. These measurements cannot provide a regional picture of how much pollution is emitted, where it comes from, and how it varies over time. In addition, there is some evidence the ground-based instruments are not placed in the areas most prone to pollution, biasing our view of poor air quality.

In contrast, the view from space gives a regional perspective, better answering the question of how pollution changes from territory to territory. Satellite-based instruments are tuned to identify key pollutants, and are agnostic to the areas they measure, removing biases associated with ground-level measurements.

Unfortunately, previous generations of space-based instruments suffered from two critical issues – limited spatial and temporal resolution. While scientists have used satellites to generate snapshots of poor air quality, we still lack the data to fully understand regional variability. As a result, the world has been hampered in its attempts to ameliorate the devastating consequences of poor air quality for human health and ecosystems.

Fortunately, things are beginning to change. The Geostationary Environment Monitoring Spectrometer (GEMS), built for South Korea and launched in 2020, is the first in a new generation of satellites observing air pollution every daylight hour with around a 5-kilometre resolution. GEMS operates over the Korean peninsula and the broader Asia-Pacific region, and is helping scientists to pinpoint more accurately what the pollutants are, where they are coming from, and to get a precise idea of where they are moving. With that kind of information, governments, local authorities and businesses are better equipped to identify concerning areas and to make informed decisions about what action to take. Non-governmental organizations and the wider civil society can also use the information to hold governments and industries accountable for the quality of air we breathe.

Next year a sister satellite instrument, built for NASA and named Tropospheric Emissions: Monitoring Pollution (TEMPO), will do a similar job over North America, with slightly better spatial resolution. In 2024, Europe will have similar coverage with the Sentinel-4 mission.

As things stand, however, neither the Global South nor the Middle East will have similar coverage. Nonetheless, these regions are particularly vulnerable to poor air quality. Deaths in Africa from outdoor air pollution have increased nearly 60% in the last 30 years, but there are no current plans to use a GEMS or TEMPO in the region. As the University of Chicago highlighted recently, investment in tackling air pollution lags far behind the scale of the problem, a situation that urgently needs to be addressed.

As we look ahead, a global constellation of geostationary orbit air quality satellites that report, on an hourly basis, the main air pollutants affecting human health will give us pertinent information for actions. We need a future where people can get instantaneous air quality data and air quality forecasts, in exactly the same way we get weather and ultraviolet information today. Clean air is a basic human right and actionable data will drive change and promote environmental justice.