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Asthma Health Center

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Asthma Risk Factors

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Allergies Linked to Asthma

Allergies and asthma often coexist. Indoor allergies are a predictor of who might be at risk for an asthma diagnosis. One nationwide study showed levels of bacterial toxins called endotoxins in house dust were directly related to asthma symptoms and use of asthma inhalers, bronchodilators, and other asthma drugs.

Sources of other indoor allergens include animal proteins (particularly cat and dog allergens), dust mites, cockroaches, fungi, and mold. Changes that have made houses more "energy-efficient" over the years are thought to increase exposure to these causes of asthma.

Environmental Factors and Asthma

Indoor air pollution such as cigarette smoke, mold, and noxious fumes from household cleaners and paints can cause allergic reactions and asthma. Environmental factors such as pollution, sulfur dioxide, nitrogen oxide, ozone, cold temperatures, and high humidity are all known to trigger asthma in susceptible individuals. In fact, asthma symptoms and hospital admissions are greatly increased during periods of heavy air pollution. Ozone is the major destructive ingredient in smog. It causes coughing, shortness of breath, and even chest pain -- and can boost the susceptibility to infection. Sulfur dioxide, another component of smog, also irritates the airways and constricts the air passages, resulting in asthma attacks.

Gas stoves are the primary source of indoor nitrogen dioxide, a common indoor pollutant. Studies show that people who cook with gas are more likely to have wheezing, breathlessness, asthma attacks, and hay fever than those who cook with other methods. It is estimated that more than half of the households in the U.S. use gas stoves.

Weather changes can also result in asthma attacks in some people. For instance, cold air causes airway congestion and an increase in mucus production. Increases in humidity may also cause breathing difficulty in a certain population.

Cigarette Smoke Is an Asthma Risk Factor

Several studies confirm that cigarette smoking is linked with an increased risk for developing asthma. There's also evidence that cigarette smoking among adolescents increases the risk of asthma. Even more findings link secondhand smoke exposure with the development of asthma in early life.

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