Related by context. Frequent words. (Click for all words.) 63 respiratory tract 53 digestive tracts 50 nasal passages 50 mucous membranes 49 lungs 48 mucus membranes 48 respiratory secretions 48 bronchial tubes 46 thyroid glands 46 Ultraviolet light 46 pharynx 45 secretions 45 Inhaling 45 Cigarette smoke 45 aggravate asthma 44 respiratory illnesses 44 endotoxins 44 chronic cough 44 inhale 44 throat irritation 44 Hydrogen sulfide 44 sinus congestion 44 digestive tract 44 pulmonary diseases 44 sweat glands 44 intestines 43 coughing wheezing 43 respiratory infections 43 intestinal tracts 43 ammonia fumes 43 bronchi 43 granulomas 43 asthma bronchitis 43 respiratory diseases 43 burning sensation 43 windpipes 43 skin rashes 42 pet dander 42 sebaceous glands 42 nostrils 42 sneezing coughing 42 upper respiratory tract 42 metabolically active 42 cigarette smoke 42 GI tract 42 detoxifies 42 acrolein 42 respiratory droplets 42 salivary glands 42 alveoli 42 genital tract 42 inflammations 42 Prolonged exposure 42 retinas 41 sensory nerves 41 airways 41 pneumonias 41 rashes 41 nasal passage 41 redness swelling 41 toxic byproducts 41 exhalations 41 carcinogens 40 lung 40 aerosolized 40 lung tissue 40 gastrointestinal tract 40 asthma emphysema 40 respiratory 40 skin lesions 40 respiratory ailments 40 parasitic worms 40 itchiness 40 bacterial viral 40 pleura 40 inhaled 40 Passive smoking 40 mucosa 40 sinuses 40 lung diseases 40 noxious chemicals 40 watery eyes 40 dehydrates 40 tissues 40 lung inflammation 40 putrid smell 40 pus filled 40 respiratory symptoms 40 liver spleen 40 fungal spores 40 mucous membrane 40 caustic chemicals 40 bile acids 40 harmful toxins 40 toxicants 40 skin irritations 40 air sacs 39 loose stools 39 trigeminal nerve 39 Particulate matter 39 conjunctiva