Aerosolised and settled contaminants are from the environment and can be brought to the product by air currents or personnel. The body has glands all over, each producing its own substance. Oils, sweat, saline, saliva, and wax are some of the substances so produced that have the potential to contaminate the environment. Hair becomes statically charged on combing, and attracts dust. Oiled hair retains the dust better than dry hair.
Dry hair is brittle and breaks easily.
Hair also produces a protein called keratanin, which is released into the environment. And this aerosol is exhaled from a distance as close as 20-40 cms from sensitive work place. Inparticular, the exhaled air is rich with dust and other allergens that the lung is anxious to be rid of. Smokers breathe out more contaminants than non-smokers, even several hours after they have last smoked. Drinking water after smoking helps slightly reduce the number exhaled.