[Strategies in the prevention and control of the Covid-19 pandemic caused by SARS-CoV-2. Environmental factors.]

The role that environmental factors can play in preventing and controlling the Covid-19 epidemic was explored and compared to that of influenza. Papers cited by the U.S. National Academy of Sciences were discussed, which indicate that temperature and humidity in the environment can influence the intensity of the spread of the disease. The fact that influenza viruses and coronaviruses appeared seasonally, prevailing in the winter and declining in the summer, was illustrated. It was discussed that ultraviolet light in the environment can contribute to the control of the spread of the virus. A study was cited to suggest that particulate matter contributes to increased infection mortality, and that it increases in summer in some regions, countering the health effects of humidity and temperature. Data generated by online electronic tools was compared with surveillance reports generated by the U.S. Centers for Disease Control and Prevention. The epidemic began stronger in northern hemisphere countries during the northern winter. (Evidence that the epidemic intensified during the southern winter is not disputed.) The incidence declined in the northern hemisphere during the summer, except for the U.S., where cases doubled. Evidence suggests that the high degree of SARS-CoV-2 infection counteracts the role that environmental factors may play in Covid-19 control.