How about smoke and other things in the air?

Exposure to environmental irritants is a well recognized cause of voice dysfunction. Smoke, dehydration, pollution and allergens may produce hoarseness, frequent throat clearing and voice fatigue. These problems can generally be eliminated by environmental modification, medication, or simply breathing through the nose rather than the mouth since the nose warms, humidifies and filters incoming air.

The deleterious effects of tobacco smoke upon the vocal folds have been known for many years. Smoking not only causes chronic irritation, but moreover can result in histologic (microscopic) alterations in the vocal fold epithelium. The epithelial cells change their appearance, becoming more and more different from normal epithelial cells. Eventually, they begin to pile up on each other, rather than lining up in an orderly fashion. Eventually, they escape normal homeostatic controls, growing rapidly without restraint and invading surrounding tissues. This drastic change is called squamous cell carcinoma, or cancer of the larynx.

Can foods or drugs affect the voice?

The use of various foods and drugs may affect the voice, too. Some medications may even permanently ruin a voice, especially androgenic (male) hormones such as those given to women with endometriosis, or with post-menopausal sexual dysfunction. Similar problems occur with anabolic steroids (also male hormones) used illicitly by body builders. More common drugs also have deleterious vocal effects, usually temporary. Antihistamines cause dryness, increased throat clearing and irritation, and often aggravate hoarseness. Aspirin contributes to vocal fold hemorrhages because of the same anticoagulant properties that make it a good drug for patients with vascular disease. The propellant in inhalers used to treat asthma often produces laryngitis. Many neurological, psychological and respiratory medications cause tremor that can be heard in the voice. Numerous other medications cause similar problems. Some foods may also be responsible for voice complaints in people with "normal" vocal folds. Milk products are particularly troublesome to some people because the casein they contain increases and thickens mucosal secretions.