Modifiers matching impurity:

• unwanted,
• airborne,
• physical,
• harmful,
• active,
• volatile,
• microscopic,
• soluble,
• undesired,
• chemical,
• environmental,
• possible,
• coarse,
• stubborn,
• heavier,
• light,
• colloidal,
• harmless,
• little,
• minute,
• polar,
• fine,
• visible,
• reactive,
• mechanical,
• natural,
• foreign,
• inorganic,
• atmospheric,
• insoluble,
• organic,
• common,
• biological,
• residual,
• small,
• solid,
• heterogeneous,
• gaseous,
• absorptive,
• sticky,
• dilute,
• smaller,
• lighter,
• out,
• minor,
• lightweight,
• up,
• separate,
• desirable,
• mental,
• micro,
• off,
• ordinary,
• anionic,
• suspended,
• random,
• nonpolar,
• unavoidable,
• corrosive,
• particulate,
• mobile,
• hazardous,
• fluid,
• interfering,
• dissolved,
• initial,
• ionic,
• damaging,
• homogeneous,

Simple categories matching harmless:

• component,
• substance,
• prey,
• food,
• animal,
• material,
• critter,
• souvenir,
• agent,
• thing,
• rodent,
• antigen,
• metabolite,
• creature,
• plant,
• impurity,
• solid,
• item,
• matter,
• salt,
• fluid,
• preparation,
• object,
• powder,
• bird,
• snake,
• gas,
• stuff,
• sugar,
• residue,
• being,
• insect,
• foodstuff,
• pollutant,
• compound,
• ingredient,
• disorder,
• contaminant,
• preservative,
• particle,
• spider,
• medication,
• bug,
• carrier,
• metal,
• organism,
• crime,
• allergen,
• liquid,
• constituent,
• drug,
• activity,
• chemical,
• task,
• neighbor,