Indoor Air Pollution was Nonnegligible during COVID-19 Lockdown

COVID-19 spread globally in the past months and caused hundreds of thousands of people dead. Many countries took lockdown policy to restrict human activities and industry to slow down the virus spread. The implementation of stringent lockdown resulted in less traffic and industrial emissions, thus reduction of various ambient air pollutants were observed in urban areas. Considering people stayed longer time in indoor, the indoor air pollution (IAP) might play a more important role for human health during lockdown. People suffered from high possibility of IAP exposure risk increase during lockdown as they almost stayed at home the whole day. Unfortunately, available studies on IAP and its health impact during this period were rare compared with those on ambient air. By this, more investigations should be performed to estimate the impact of global COVID-19 lockdown on human health in the future.