that area of collective NBC protection which is airtight, pressurized and fed with clean filtered air and designed to be toxic free where personnel need not wear individual NBC protective equipment, kollektiivses TBK-kaitses hermeetiline ja puhta, filtreeritud õhuga mürkidest vaba ala, kus isikkoosseis ei pea kandma isiklikke massirelvavastaseid kaitsevahendeid