In the first weeks of the global Covid-19 pandemic, people desperate for good news received a small glimmer of hope: the Himalayas were once again visible, spanning the northern Indian horizon for what could be the first time in 30 years.

As cities around the world came to a standstill in March and April to curb the rapid spread of the virus, many urban residents saw a silver lining where air pollution was concerned. Kenyans reported seeing the jagged peaks of Mount Kenya from behind Nairobi’s skyscrapers, and NASA satellite data showed a drop in pollution on roads through the northeastern corridor of the United States.

“This is stark confirmation of the contribution of our daily activities to the sources of emissions of the air pollutants we breathe and the greenhouse gases that drive global warming,” the Climate and Clean Air Coalition (CCAC) Science Advisory Group and invited experts wrote in May. “The speed with which emissions have fallen demonstrates how quickly we can improve our environment when motivated and how vulnerable we are to living in degraded environments.”

As the Acting Secretary General of the European Public Health Alliance (EPHA) said: “The air may be clearing in Italy, but the damage has already been done to human health and people’s ability to fight infections. Governments should have tackled chronic air pollution long ago, but they have prioritised economics over health. Science tells us that epidemics like COVID-19 will occur with increasing frequency. So, cleaning up the streets is a basic investment in a healthier future. Two images taken by NASA’s Sentinel-5 satellite show the concentration of nitrogen levels over China before and after the closure of COVID.