Modifiers matching emission:

• unwanted,
• industrial,
• harmful,
• liquid,
• natural,
• secondary,

Simple categories matching harmful:

• complication,
• chemical,
• medication,
• thing,
• substance,
• environment,
• mineral,
• pesticide,
• frequency,
• organism,
• material,
• drinking,
• metal,
• influence,
• drug,
• sweetener,
• filler,
• therapy,
• plant,
• curio,
• radiation,
• experience,
• power,
• pollutant,
• contaminant,
• compound,
• defect,
• intruder,
• microorganism,
• aggression,
• adulterant,
• fraction,
• bacteria,
• emotion,
• stress,
• content,
• illness,
• action,
• abnormality,
• fish,
• stimulus,
• test,
• event,
• component,
• choice,
• constituent,
• fluid,
• habit,
• sport,
• pathology,
• fat,
• microbe,
• group,
• toxin,
• light,
• creature,
• aerosol,
• fiber,
• intervention,
• oxidant,
• nutrient,
• particle,
• allergen,
• practice,
• result,
• antigen,
• infection,
• parasite,
• article,
• yeast,
• notion,
• deeds,
• stuff,
• bug,
• state,
• problem,
• subsidy,
• danger,
• stain,
• pathogen,
• diuretic,
• occupation,
• utterance,
• invertebrate,
• contamination,
• caterpillar,
• occurrence,
• ion,
• solvent,
• fumes,
• situation,
• procedure,
• fauna,
• stimulant,
• act,
• agent,
• code,
• gas,
• circumstances,
• volatile,
• animal,
• element,
• process,
• tool,
• object,
• quality,
• effect,
• entity,
• commodity,
• item,
• solute,
• deposit,
• disorder,
• sector,
• matter,
• crime,
• conduct,
• industry,
• trait,
• germ,
• virus,
• herb,
• ingredient,
• place,
• irradiation,
• flavoring,
• change,
• work,
• intermediate,
• fuel,
• halogen,
• emission,
• product,
• activity,
• energy,
• exposure,
• sediment,
• service,
• force,
• salt,
• atmosphere,
• software,
• reactant,
• information,
• cause,
• property,
• weather,
• radical,
• consequence,
• factor,
• disease,
• liquid,
• treatment,
• pest,
• alkaloid,
• symptom,
• cell,
• arachnid,
• predator,
• preservative,
• weeds,
• tax,
• gene,
• condition,
• waste,
• monomer,
• program,
• email,
• behaviour,
• molecule,
• idea,
• impurity,
• addiction,
• elements,
• residual,
• beverage,
• phenomenon,
• inhalant,
• food,
• behavior,
• residue,
• insect,
• fumigant,