Some factors contributing to the incidence of the United States are : 1) environmental factors are a main contributor to asthma and allergies. Allergic asthma is triggered by allergens like dust, pet dander, or cockroaches. Non-allergic asthma is usually caused by exercise, stress, smoke, or airway infections. 2) Indoor and outdoor trigger include: smoke pollution and strong odors, pet dander, mold, pollen, dust, mites, exercise, pests like roaches and mice, colds and flus, certain foods, and changes in the weather. A better understanding of the factors that cause asthma is immediately needed, so it could be used to develop public health and pharmacological primary prevention measures that are effective in reducing the prevalence of asthma worldwide. Public health efforts should be focused on measures to improve lung and general health, such as: reducing tobacco smoking and environmental tobacco smoke exposure; reducing indoor and outdoor air pollution and occupational exposures; reducing childhood obesity; encouraging breastfeeding; promoting childhood vaccinations; and reducing social inequalities.
