<s>[INST] Have measures to contain COVID-19 reduced air pollution and emissions of greenhouse gases? [/INST] Air pollution is a serious health risk. It kills approximately 7 million people every year and is responsible for one third of all deaths from stroke, lung cancer and heart disease. Over 90% of the global population lives in places where the WHO outdoor air quality guideline levels are not met, and about two-thirds of this exposure is caused by burning of fossil fuels, which also drives climate change.

Efforts to control COVID-19 transmission have reduced economic activity and led to temporary improvements in air quality in some areas. In contrast, as carbon dioxide and other greenhouse gases that drive climate change persist for a long time in the atmosphere, temporary emissions reductions only have a limited effect on atmospheric concentrations. Carbon dioxide levels at observing stations around the world in the first months of 2020 have been higher than in 2019.

Environmental improvements resulting from the COVID-19 response may be reversed by a rapid expansion of polluting economic activities once the measures have ended, unless there is a clear focus to promote equity, environmental health, around a just transition to a green economy.

Any short-term environmental benefits as a result of COVID-19 come at an unacceptable human and economic cost, and are no substitute for planned and sustained action on air quality and climate. Source: WHO. Link: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/question-and-answers-hub/q-a-detail/coronavirus-disease-covid-19-masks. Field: Infectious Disease. Disease: COVID </s>