Modifiers matching contamination:

• common,
• external,
• airborne,
• harmful,
• charged,
• irritating,
• fragile,
• organic,
• metal,
• light,
• particulate,
• incidental,
• industrial,
• possible,
• environmental,
• liquid,
• cross,
• fecal,
• minor,
• up,
• unwanted,
• atmospheric,
• residual,
• visible,
• polar,
• animal,
• chemical,
• biological,
• inorganic,
• potential,
• inert,
• heavier,
• volatile,
• penetrating,
• metallic,
• deleterious,
• internal,
• hazardous,
• natural,
• high,
• interfering,
• physical,
• gross,
• off,
• heavy,
• insoluble,
• soft,
• regulated,
• overhead,
• foreign,
• nonpolar,
• regular,
• solid,
• microbial,
• gaseous,
• toxic,
• active,
• hydrophilic,
• salt,
• undesired,
• molecular,
• alkaline,
• basic,
• colloidal,
• loose,
• fluid,
• extraneous,

Simple categories matching gaseous:

• fuel,
• matter,
• waste,
• olefin,
• hydrocarbon,
• chemical,
• acid,
• odor,
• state,
• compound,
• flow,
• substance,
• pollutant,
• fluid,
• constituent,
• oxide,
• alkane,
• medium,
• contaminant,
• impurity,
• plasma,
• agent,
• atmosphere,
• contamination,
• salt,
• sulphide,
• material,
• monomer,
• component,
• mass,
• cyanide,
• molecule,
• anesthetic,
• phenomenon,
• reactant,
• substrate,
• alkyne,
• carrier,
• object,
• system,
• body,
• anaesthetic,
• buffer,
• precursor,
• form,
• mixture,
• fumigant,