The early part of the COVID pandemic led to a significant reduction in air pollution in many parts of the world. With lockdowns, travel restrictions and decreased economic activity, there was a noticeable drop in the emission of air pollutants, such as nitrogen dioxide (NO₂) and particulate matter (PM) that is fine enough to be inhaled.
Changes in air pollution varied depending on the location and the type of pollutant, but reductions were particularly noticeable in cities and industrial areas, where emissions from transport and industrial activities are typically high. In many areas though, air pollution levels quickly increased again as restrictions eased and activity resumed.
