... such as benzene,formaldehyde and other pernicious gases.4.Used in super stores,home,airport,hospital, ... such as benzene,formaldehyde and other pernicious gases.4.Used in super stores,home,airport,hospital, ... such as benzene,formaldehyde and other pernicious gases.4.Used in super stores,home,airport,hospital, ... as benzene,formaldehyde and other pernicious gases.4.Used in super stores,home,airport,hospital, ...