Any number of environmental stimuli can trigger asthma attacks including air temperature, respiratory viruses, pollution, odors, certain foods such as sulfites, allergens, stress, chemicals, dust, and cigarette smoke (active or passive). Some asthmatics are allergic to aspirin and ibuprofen, especially those with the "allergic triad" of asthma, nasal polyps, and sinusitis.

Asthma may be genetically inherited or acquired, usually through a viral infection. Adults who are susceptible usually get asthma as a result of viral or respiratory infections. One of the leading causes of asthma in children is second-hand cigarette smoke. Although they may grow out of it, there is still a chance that asthma may reappear when they are adults.

Allergens

An allergen is a foreign substance, one your body does not produce, that causes you to have an allergic reaction. These allergens can be absorbed by your body through your airways, namely your nose and throat - you breathe them in. If you are asthmatic, you have particularly sensitive or extra-irritable airways that react to these allergens by becoming inflamed.

Infection

Viral infections, such as the common cold or flu, may bring on asthma attacks. If a bad flu develops into a severe bronchial infection and is left untreated, asthma may develop as a permanent condition.

Sinusitis is an inflammation of your nasal sinuses and often begins as an upper respiratory infection. Asthma may be aggravated by drainage of mucus into your nose, throat, and bronchial tubes. Symptoms of sinusitis in children include wheezing, postnasal drip, nighttime cough, and enlarged lymph nodes. Adolescents and adults may suffer headaches and sinus pressure and pain.

Weather

Cold and rainy days bring increased humidity, which causes a sudden temperature change. If you are asthmatic, these conditions can irritate and narrow your airways, which in turn can bring on coughing attacks and breathlessness.

Exercise

Cool, dry air, like that found in a gym or air conditioned exercise facility, can trigger an asthma attack in people who are susceptible. Rapid breathing in and out can also cause airway irritability because it dries the airways. Long term, strenuous activities, such as long distance running, are most likely to induce an attack while swimming is least likely. This type of asthma is known as exercise induced asthma or exercise induced bronchospasm.

Work environment

Occupational asthma is a very real illness and can take months or years to manifest. Chemicals, such as isocyanates, can act as asthma triggers and are found in industries like insulation installation, spray painting, plastics, rubber and foam manufacturing. Hydrochloric acid, sulfur dioxide, and ammonia, all used in the petroleum industries, also act as irritants. Airborne fumes and irritants from factories, pulp mills, and sulfur dumps can trigger asthma attacks in people who live nearby.