BBC skepticBut Prof Alan McNally from Birmingham University was not convinced."I think this is just another test being marketed with absolutely no robust, independent validation and testing, and I would say I am extremely sceptical on its use."He said that it would need "an incredible amount of independent testing".He also said it was unclear what the procedure for schools and businesses would be if the alarm sounded: "How exactly one would act if Covid in the air was detected is rather beyond me.