The COVID-19 pandemic and the mobility limitations imposed to try to contain its spread have led to a drastic decrease in emissions of air pollutants and CO2. For the former, the drop in the atmospheric concentrations of the main urban air pollutants leads to a decrease in mortality attributable to air pollution. This has not been the case in the case of CO2 emissions; though they have decreased by close to 8%, that is insufficient to show a measurable impact in the context of the climate crisis. On the other hand, social distancing measures can have counterproductive effects on other prevention systems related to health effects aggravated by climate change, such as in the case of heat waves.