Nearly six million Californians suffer from asthma symptoms or asthma-like breathing problems.

In California, 4.5 million adults, adolescents and children had been diagnosed with asthma (13% of all Californians) in 2003, up from four million (12%) in 2001. This increase is consistent in younger children, adolescents and adults (Exhibit 1). Nationally, 10% of the population has been diagnosed with asthma. Among the 4.5 million Californians diagnosed with asthma, more than 2.5 million suffered from an asthma attack or other asthma symptoms in 2003 (56% of those diagnosed). An additional 3.4 million Californians who have not been diagnosed with asthma-10% of all Californians-suffer from asthma-like breathing problems. Some of these respondents might have other respiratory conditions, while others are likely to have asthma that has not been diagnosed. Based on data from the 2003 California Health Interview Survey (CHIS 2003), this policy brief examines the prevalence of lifetime asthma diagnoses and asthma symptoms, as well as the prevalence of asthma-like breathing problems in the absence of an asthma diagnosis. Where possible, it also describes how prevalence has changed since 2001, based on data from CHIS 2001. Lifetime prevalence refers to people who have ever been diagnosed with asthma by a doctor. The prevalence of asthma symptoms refers to people who report having been diagnosed with asthma and who also reported experiencing an asthma attack or other asthma symptoms in the past year. The prevalence of asthma-like symptoms refers to people who have not been diagnosed with asthma but who experienced breathing problems, such as wheezing or whistling in the chest in the past year.