All types of tobacco smoke are extremely harmful to a person with asthma. There are generally two different ways an individual can come into contact with tobacco smoke:

• Directly inhaled smoke. Sucking on the end of a cigarette, cigar or pipe and pulling tobacco smoke directly into the lungs. The smooth muscle that surrounds the airways in a person with asthma is very sensitive. Exposing this muscle to the numerous chemicals found in tobacco smoke (e.g., ammonia, hydrogen cyanide) can cause an immediate asthma attack as the muscle squeezes down and obstructs the airway.
  
  
• Second-hand smoke. Also known as passive smoke, this type is generally inhaled by people in the same room or area as a smoker. It includes:
  
  
• Sidestream smoke. Type of smoke produced from the burning material itself, and not directly inhaled and exhaled by the smoker.
  
  
• Mainstream smoke. Smoke directly inhaled by the smoker (through a cigarette, cigar or pipe) and then expelled out into the air.

While inhaling second-hand smoke may seem less harmful than actually smoking, it is actually more harmful. This is because second-hand smoke contains higher concentrations of many harmful substances, including twice the amount of tar and nicotine and three times the amount of carbon monoxide.

Even though wood smoke contains far less of the dangerous chemicals associated with tobacco smoke, asthma sufferers should also try to stay away from wood burning stoves and fireplaces. Studies have demonstrated that wood smoke can cause an increase in respiratory symptoms, lowered respiratory function and lowered pulmonary function.

Smoke from candles and incense may also exacerbate the respiratory conditions of a person with asthma. The U.S. Environmental Protection Agency (EPA) advises individuals with asthma to remove candles and incense from the home.