Asthma is a chronic disease of the airways in which breathing becomes difficult due to inflammation of the air passages, resulting in a temporary narrowing of the airways that deliver oxygen to the lungs. It can be brought on my many factors, including allergens, exercise, smoke (tobacco or otherwise), perfumes, changes in humidity, and strong emotions such as anxiety, laughing, or crying. When the airways become irritated due to animal fur or dander, pollen, dust, or fumes, they narrow and cause coughing and wheezing. The bronchial tubes of those with asthma are red and swollen, or inflamed, and exercise aggravates this effect. Asthma can occur at any age, but is increasingly prevalent in children. In fact, nearly one in 10 American children now has asthma. Asthma causes 4,000 deaths a year in the United States. Medicines such as inhaled short-acting beta-2 agonists may be used to treat acute attacks.

Since cannabinoids has been found to reduce inflammation, it can be extremely beneficial to those with asthma. A study done by Hartley, Nogrady, and Seaton that was published in the "British Journal of Clinical Pharmacology" entitled "Bronchodilator Effect of Δ1-Tetrahydrocannabinol" found:

1. Δ1-trans-tetrahydrocannabinol, (Δ1-THC) produces bronchodilatation in asthmatic patients.

2. Administered in 62 microliter metered volumes containing 50-200 microgram by inhalation from an aerosol device to patients judged to be in a steady state, it increased peak expiratory flow rate (PEFR) and forced expiratory volume in 1 second (FEV1).

3. The rate of onset, magnitude, and duration of the bronchodilator effect was dose related.