Causes

More than 250 workplace substances have been identified as possible causes of occupational asthma. These substances include:

• Animal substances, such as proteins found in dander, hair, scales, fur, saliva and body wastes.
• Chemicals used to make paints, varnishes, adhesives, laminates and soldering resin. Other examples include chemicals used to make insulation, packaging materials, and foam mattresses and upholstery.
• Enzymes used in detergents and flour conditioners.
• Metals, particularly platinum, chromium and nickel sulfate.
• Plant substances, including proteins found in natural rubber latex, flour, cereals, cotton, flax, hemp, rye, wheat and papain — a digestive enzyme derived from papaya.
• Respiratory irritants, such as chlorine gas, sulfur dioxide and smoke.

Asthma symptoms start when your lungs become irritated (inflamed). Inflammation causes several reactions that restrict the airways, making breathing difficult. With occupational asthma, lung inflammation may be triggered by an allergic response to a substance, which usually develops over time. Alternatively, inhaling fumes from a lung irritant, such as chlorine, can trigger immediate asthma symptoms in the absence of allergy.