If you were in space right now, what would the earth look like?
It would probably look the way it always looks like in pictures - a globe covered by large areas of blue ocean interspersed by green and brown land masses and swirling clouds.
What you wouldn’t see is the air we breathe, and how polluted it might be. Industrial production, transportation, human activity and natural causes all influence pollution levels, which are also affected by climate, temperature and weather patterns. Air pollution directly impacts the health of those with a predisposition to cardiovascular and respiratory diseases, but in reality it affects everyone’s health and prosperity. (The economic burden of pollution associated with premature mortality and morbidity is equivalent to five to 14 percent of countries' GDPs.)
On the ground, air pollution has to be significant to be noticed by the human eye, but that doesn’t mean it’s not “seen” from space. In fact, satellites are capturing this “invisible to the eye” data, showing where the pollution is the worst.
Many countries already have machinery in place to collect data on air pollution, but these are often concentrated in cities and don’t reflect circumstances across the nation. Moldova’s national air monitoring system is updated daily, using information from 17 monitoring stations (based on manual sampling), but only a handful of cities and towns are covered by the system. The Ukrainian public network of air pollution sensors is also not producing enough, and its expansion is growing too slowly. Citizen-led projects are promising, but they have yet to cover the entire country and experts often doubt the reliability of those measurements.
So what about using those satellites to gather a more complete set of data? UNDP Moldova and UNDP Ukraine partnered with the European Space Agency and their EO Clinic programme to test the applicability of satellite data to understand air pollution and which regions are most vulnerable.
The research team used satellite data provided by Sentinel 5P – a cutting edge satellite technology equipped with latest technologies for atmospheric measurements - to analyse the main air pollutants: ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2) and particulate matter (PM10 and PM2.5). They were testing the applicability of satellite data to understand air pollution, how it changed during COVID lockdowns and which regions are most vulnerable – looking at the past three years.
Using this new data, the two countries were able to draw conclusions, published this past spring. Here’s a sample of what they found:
It’s no surprise that pollution hotspots were glaring in cities with heavy industry. The biggest polluters aligned with high nitrogen dioxide areas, and data showed these emitters might be more significant than other forms of pollution.
Particulate matter not only affects air in the locations of pollution, but risks affecting a far wider geographical range since it’s easily carried by the wind. At Ukraine’s national level, the average annual concentration of PM2.5 of 10 μg/m3 was reached or exceeded in 16 out of 36 months monitored. Higher concentrations are observed in the spring and autumn months, which may lead to a 15 percent increase in mortality.
(The animation below shows how far can the dust be taken by wind from the source of origin.)