The new coronavirus infection has brought about many changes in the world, but lockdown has significantly reduced air pollution levels in many heavily polluted cities.
Even in India, one of the most polluted cities in the world, there have been numerous reports that a clean blue sky has returned after a severe lockdown began on March 2020, 3.In order to investigate the anthropogenic effects of lowering the concentration of air pollutants, it is necessary to distinguish them from the effects of natural phenomena in the atmosphere such as wind flow.Therefore, researchers led by the Research Institute for Humanity and Nature have developed a new research method using satellite data and mathematical modeling, which is one of the air pollutants in Delhi, the capital of India, and its surrounding areas. The effect of lockdown on nitrogen oxide levels was investigated.
This method analyzed seasonal and annual satellite data over several years to predict nitrogen oxide levels in the absence of lockdown.We also analyzed the top-down emissions of nitrogen oxides estimated based on the concentration in the atmosphere using the continuity equation in the steady state.The results show that natural phenomena alone cannot explain the dramatic decline in nitrogen oxide levels in 2020.
Estimated changes in nitrogen oxide emissions in urban areas also show that 72% of emissions are due to human activity solely due to transportation and factories.On the other hand, it was also found that the concentration of nitrogen oxides increased more immediately in rural areas than in urban areas after the lockdown was resolved. It is said that the activity was resumed immediately.
The research method developed this time is expected to help guide appropriate policy decisions regarding future air pollution by distinguishing human-induced effects from natural effects.
Paper information:[Scientific Reports] Nitrogen oxides concentration and emission change detection during COVID-19 restrictions in North India
