The air quality during the confinement and coronavirus 2020-2021 period.

At the end of 2019, the first cases of coronavirus (COVID-19) were reported in Wuhan, China. A month later, that epidemic turned into a national crisis, with infected individuals diagnosed all over China. In early March 2020, the World Health Organization (WHO) declared that the Wuhan epidemic has turned into a global pandemic. Many European countries have started to know several cases affected by this coronavirus, which is known to be highly contagious. The WHO has launched several recommendations to curb the spread of this virus and to call for the establishment of general confinement in the affected countries. Tunisia quickly took this step on March 22 and announced immediate general confinement for two weeks, renewable according to the tests results. Factories have been closed to limit human damage. International flights have been halted and the majority of government and private services have been halted except minimum and emergency services. Following these successive events, the air quality has improved markedly during the confinement period. NASA scientists say the reduction in NO2 pollution first appeared near Wuhan Northern Italy and France experienced a reduction of nearly 50% of their NO2 emissions during this period of confinement (March-April) and been reduced by almost 30% in China. In Tunisia, nitrogen dioxide (NO2), sulfur dioxide (SO2) and carbon monoxide (CO) showed a remarkable decrease in the north and the center of Tunisia of more than 40% during this period mainly linked to the reduction in emissions from road traffic and industries. Also these pollutant gases concentrations have knew a nearly 50% reduction during the 3rd pandemic wave during the period of January-April 2021. Consequently, the air quality has improved significantly in Tunisia and around the world.