• pollen
• mold
• animal protein (dander, urine, oil from skin)
• house dust/dust mites
• cockroach droppings 
• certain foods

• strong odors and sprays, such as perfumes, household cleaners, cooking fumes, paints, and varnishes
• chemicals such as coal, chalk dust, or talcum powder
• air pollutants such as tobacco smoke, wood smoke, chemicals in the air, and ozone
• changing weather conditions, including changes in temperature, barometric pressure, humidity, and strong winds
• Chemical exposure on the job, such as occupational vapors, dust, gases, or fumes.

Medications, such as aspirin and additives such as sulfites, cause up to 20 percent of adult asthmatic attacks as a result of sensitivities or allergies to them. These medications often include:

• aspirin
• other non-steroidal anti-inflammatory medications, such as ibuprofen, indomethacin, naproxen
• sulfites used as preservatives in food and beverage

Before taking any medication, including over-the-counter medications, talk with your physician.

Strenuous physical exercise can trigger an asthma attack, often because of the inhaled cool and dry air. Long-term strenuous activities such as long distance running, are most likely to induce asthma, and swimming is the least likely.

GERD, or indigestion, a condition characterized by persistent reflux of stomach acids, is common in individuals with asthma. Symptoms may include heartburn, belching, or spitting up in infants.

Tobacco smoke, whether directly or passively inhaled, has been shown to have harmful effects on the airways.

Wood smoke from wood-burning heating stoves and fireplaces can release irritating chemicals such as sulfur dioxide.

Reactions from stress and anxiety are considered to be more of an effect than a cause. They can cause fatigue, which may affect the immune system and, in turn, increase either asthma symptoms or bring on an attack.