Every year, aerosol contribute to unhealthy levels of air pollution in many Indian cities.
NASA satellite sensors have observed that aerosol levels in North India have dropped to 20-year-lows for this time of the year.
Human activity has been minimal with the country under a coronavirus-led lockdown for over a month. This has also led to a reduction in vehicular and industrial emissions.
After just a week of reduced human activities, the aerosol levels were observed at a 20-year low for this time of year in northern India, said the US space agency.
What are aerosols?
Aerosols are tiny solid and liquid particles suspended in the air that reduce visibility and can damage the human lungs and heart. Some aerosols have natural sources, such as dust storms, volcanic eruptions, and forest fires. Others come from human activities, including the burning of fossil fuels and croplands. Human-made aerosols tend to contribute most of the smaller particles that have greater potential for damaging human health.
Every year, aerosol contribute to unhealthy levels of air pollution in many Indian cities.
How aerosol level plummet in Northern India?
In a typical early spring in the Ganges Valley of northern India, human activities generate the majority of aerosols.
The aerosol decrease was observed in the first week of the lockdown, but that was due to a combination of rain and the lockdown, said Pawan Gupta, a Universities Space Research Association (USRA) scientist at NASA’s Marshall Space Flight Center.
Aerosol concentrations usually increase again after such heavy precipitation. However, it didn’t go up and return to normal, said Gupta.
“We saw a gradual decrease, and things have been staying at the level we might expect without anthropogenic emissions,” he said.
In the above map shared by NASA Earth Observatory, the space agency showed how aerosol optical depth (AOD) in 2020 compared to the average for 2016-2019. AOD is a measure of how light is absorbed or reflected by airborne particles as it travels through the atmosphere. If aerosols are concentrated near the surface, an optical depth of 1 or above indicates very hazy conditions. An optical depth, or thickness, of less than 0.1 over the entire atmospheric vertical column is considered “clean.”
In southern India, the condition was different, said the report, as satellite data showed aerosol levels had not yet decreased to the same extent. In fact, levels seem to be slightly higher than in the past four years. The reasons are unclear, but could be related to recent weather patterns, agricultural fires, winds, or other factors, said the space agency.
Follow our full coverage here.Time to show-off your poker skills and win Rs.25 lakhs with no investment. Register Now!
