?? 4??? ppb ??? ??? ??? ??.
?? ???? ppb ??? ??? ??? ??? ????: .
??: ???? 2 0.5, ppb ??, ???? ? ????, ???ppb, ????? ?? ???? ??, ?? ? ??????? ??, ppb, ????, ?? ???????ppb, ppb ?? ??, ??PPB, ?? ?? ????, ppb ???, PPB ??, ppb ?? ??? ??, ?? ?? ?? ?? ??, ????? ?? ????? ??, ????? ?? ????? ??, ?? ?? ?? ppb, AS ??A ??.
?2007-2024 ??? ??