(a) gases, such as ammonia, chlorine or hydrogen chloride, fluorine or hydrogen fluoride, carbon oxides, sulphur compounds, nitrogen oxides, hydrogen, sulphur dioxide, carbonyl chloride;
a) van gassen, zoals ammoniak, chloor of chloorwaterstof, fluor of fluorwaterstof, kooloxiden, zwavelverbindingen, stikstofoxiden, waterstof, zwaveldioxide, carbonyldichloride,