Inclusion Criteria:  aged between 18 and 45 years old lack of symptoms or no contact with people with Covid-19 in the last two weeks negative antigenic test to Covid-19 in the 3 days before the experiment people who declared to have no risk factor to severe form of Covid-19 people who declared not to live in the same place as someone with these risk factors people residing in Ile-de-France area  Exclusion Criteria:  positive test to Sars-Cov-2 within 3 days before the concert people with clinical signs suggesting infectious respiratory disease people with severe Covid-19 risk factor people living with someone having severe covid-19 risk factor not affiliated to social security people who cannot remain standing for the time of the experimentation (about 5 hours) person under tutorship or curatorship pregnant women or not having effective contraception method breastfeeding women