A system for controlling environment in at least one reaction box, the system comprising: a gas inlet connector connectable to at least one gas source (200, 210, 220) comprising a respective gas; a gas outlet connector connectable to said at least one reaction box (300, 310, 320); a gas multiplexer connected to said gas inlet connector and said gas outlet connector and suitable for interconnecting a gas flow from said gas inlet connector to said gas outlet connector; a vacuum pump connected to said gas multiplexer and suitable for generating an under pressure inside said at least one reaction box (300, 310, 320) when said gas multiplexer interconnects said vacuum pump with said gas outlet connector; a controller suitable for controlling said gas multiplexer to switch between applying an under pressure in said reaction box and applying a gas flow from a gas source of said at least one gas source (200, 210, 220) to said reaction box multiple times in a cyclic manner to reduce an amount of particles present in said reaction box; a particle monitor connectable to said at least one reaction box (300, 310, 320) and suitable for generating particle information representing a concentration of particles present in said at least one reaction box (300, 310, 320), wherein said controller is suitable for controlling said particle monitor to generate said particle information representing said concentration of said particles in said reaction box following an end of the cyclic switching between applying said under pressure and applying said gas flow; and a memory configured to store said particle information generated by said particle monitor as a good manufacturing practice, GMP, clean room classification notification for said reaction box. a gas inlet connector connectable to at least one gas source (200, 210, 220) comprising a respective gas; a gas outlet connector connectable to said at least one reaction box (300, 310, 320); a gas multiplexer connected to said gas inlet connector and said gas outlet connector and suitable for interconnecting a gas flow from said gas inlet connector to said gas outlet connector; a vacuum pump connected to said gas multiplexer and suitable for generating an under pressure inside said at least one reaction box (300, 310, 320) when said gas multiplexer interconnects said vacuum pump with said gas outlet connector; a controller suitable for controlling said gas multiplexer to switch between applying an under pressure in said reaction box and applying a gas flow from a gas source of said at least one gas source (200, 210, 220) to said reaction box multiple times in a cyclic manner to reduce an amount of particles present in said reaction box; a particle monitor connectable to said at least one reaction box (300, 310, 320) and suitable for generating particle information representing a concentration of particles present in said at least one reaction box (300, 310, 320), wherein said controller is suitable for controlling said particle monitor to generate said particle information representing said concentration of said particles in said reaction box following an end of the cyclic switching between applying said under pressure and applying said gas flow; and a memory configured to store said particle information generated by said particle monitor as a good manufacturing practice, GMP, clean room classification notification for said reaction box.