California Asthma Prevalence by County and Age Group

Two tables from the California Health Interview Survey provide asthma prevalence percentages stratified by county and age group for 2-year periods. A third table from the California Behavioral Risk Factor Surveillance System offers yearly statewide data for adults aged 18 and older. The data includes lifetime and current asthma prevalence metrics.

Use Cases

• Analyze lifetime asthma prevalence trends across California counties and age groups like 0-17 or 65+
• Compare current asthma prevalence rates between different 2-year periods at the county level
• Model statewide adult asthma prevalence trends using yearly data from the BRFSS table
• Investigate disparities in asthma prevalence between pediatric (0-17) and adult (18+) age cohorts

Strengths

• Data is derived from two established public health surveys: the California Health Interview Survey (CHIS) and the California Behavioral Risk Factor Surveillance System (BRFSS)
• Includes stratification by multiple age groups: all ages, 0-17, 18+, 0-4, 5-17, 18-64, and 65+
• Provides two distinct prevalence metrics: lifetime diagnosis and current asthma status

Limitations

• The dataset's row count and specific column names are not provided, limiting assessment of granularity
• County-level data is aggregated into 2-year periods, which may obscure annual trends
• Statewide adult data is not broken down by county or sub-state geography

Provenance

Source

State of California, California Department of Public Health

Collection Method

Derived from the California Health Interview Survey (CHIS) and the California Behavioral Risk Factor Surveillance System (BRFSS)

Time Range

Data reported for 2-year periods (CHIS) and by year (BRFSS adult data); specific years not stated

Freshness

Last updated in December 2025.

Geography

California, with data available at the county level (CHIS) and statewide (BRFSS adult data)