In India, pollution has become a way of life. The air quality index regularly screams ‘hazardous’ and it’s not uncommon to see schools shutting down because of smog or citizens going to work wearing anti-pollution masks. And lest anyone forget how badly the country is choking on poisonous air, European Space Agency’s Sentinel-5P satellite has come out with a shocking reminder of the same in the form of the following image:

What you see here is the concentration of formaldehyde in the air, as measured from November 2017 to June 2018. Formaldehyde is a colorless gas produced naturally by all life forms as a part of cell metabolism. However, the amount of naturally-occurring formaldehyde is very, very small – which is a good thing because if you breathed in a lot of this gas, you could experience server respiratory problems. The US Department of Health and Human Services has, in fact, said that prolonged exposure to formaldehyde could lead to cancer in humans.

So, why is formaldehyde plaguing India in the first place? In an interview with the BBC, Isabelle De Smedt from the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), says, “It depends on the region but 50-80% of the signal is from some biogenic origin. But above that, you have pollution and fire. And the fire can be from coal burning or wildfires, but in India, yes, you have a lot of agricultural fires.” This is why you see lesser concentrations of formaldehyde over the desert area of Rajasthan in the image above. But clearly, India needs to act. And fast.

Data and insights like these are important to help countries formulate policies that could tackle the menace of air pollution in a timely manner. And ESA’s Sentinel-5P satellite is set to play a big role in this. Sentinel-5P carries the most-advanced pollution mapping sensor of its kind: Tropomi. Its ability to image air pollutants in more detail than ever before is certainly going to ensure that the dialogue around air pollution does not die down.