Nitrogen dioxide, sulfur dioxide, ozone, carbon monoxide, hydrocarbons, nitrogen oxide, and cigarette smoke are also known to precipitate asthma attacks. Fumes and strong odors, such as turpentine, paints, gasoline, perfumes, etc., disturb many asthmatics. Extrinsic asthma usually begins in childhood, is seasonal, and is usually caused by a definite number of substances which can more easily be identified. Asthma is the leading cause of disease and disability in the 2-17 age group. Intrinsic asthma is the more severe, and generally begins after 30 years of age.
Attacks can occur at any time, and the causes are much more difficult to identify.
About half of asthmatics are diagnosed between 2 and 17, another third after 30. The other one sixth does not fit either the intrinsic or extrinsic category. For example, some may initiate the problem in their 20s and others may, after their 30s, develop reactions to only one or two seasonal allergens. But asthma can be difficult to diagnose, for its symptoms are similar to those of bronchitis, emphysema, and lung infections. Over a period of time, the attacks can become more frequent, so it is best for the person with asthma to learn every possible way to lessen the problem.