2021
April
2020
December
November
October
September
August
July
June
May
April
March
February
January
2019
December
November
October
September
August
July
June
May
April
March
February
January
2018
December
November
October
September
August
July
June
May
April
March
February
January
2017
December
November
October
September
August
July
June
May
April
March
February
January
2016
December
November
October
September
August
July
June
May
April
March
February
January
![]() Public Domain by Jorge Barrios
| In closed rooms with many people - such as classrooms in schools - ventilation and masks are an important means to reduce the infection risk for Covid-19. A ventilation system in combination with a good air filter can reduce the infection risk by 40 to 50 percent. related: #Covid-19 #infection_risk |
See also @news_neat.