Data sources

Data sources

These data were obtained from three primary sources, County Health Rankings (RWJF, University of Wisconsin), Community Health Status Indicators (HHS), and asthma burden reports from the California Department of Public Health. The original sources of data are listed below.

Behavioral Risk Factor Surveillance System (BRFSS), CDC: Adult smoking estimates come from Centers for Disease Control (CDC) and Prevention's Behavioral Risk Factor Surveillance System (BRFSS), a random-digit dial survey. The estimates are based on seven years of data from 2002-2008.

Public Health Air Surveillance Evaluation (PHASE), CDC & EPA: Ozone days and Particulate matter days come from the Public Health Air Surveillance Evaluation (PHASE) project, a collaborative effort between the CDC and the EPA. PHASE used Community Multi-Scale Air Quality Model (CMAQ) outputs and air quality monitor data to calculate the number of days per year that air quality in a county was unhealthy for sensitive populations.

California Health Interview Survey (CHIS), UCLA and California Department of Public Health: Asthma prevalence data come from the California Health Interview Survey (CHIS). CHIS is a statewide telephone survey administered to over 45,000 households. This is the most comprehensive statewide asthma survey in the United States. Current data sources do not provide information about diagnosed level of asthma severity. However, both BRFSS and CHIS include information on the level of asthma symptoms, but those data are typically not sufficient for developing county-level estimates.

California Office of Statewide Health Planning and Development (OSHPD): Asthma emergency department visits and Asthma hospitalizations come from the Office of Statewide Health Planning and Development (OSHPD). OSHPD collects information on all emergency department (ED) visits in licensed hospitals in California. This data is used to calculate the extent of ED usage for asthma in the state. (2005-2007). Hospitalization data com from the 2006 Emergency Department and Patient Hospital Discharge Databases provided by the California OSHPD.

Small Area Income and Poverty Estimates (SAIPE), U.S. Census Bureau: All poverty estimates are provided by the Small Area Income and Poverty Estimates (SAIPE) program through the U.S. Census. The data are from 2007.

Variable definitions


Adult Smoking: Adult smoking prevalence is the estimated percent of the adult population that currently smokes every day or "most days" and has smoked at least 100 cigarettes in their lifetime. Each year approximately 443,000 premature deaths occur primarily due to smoking. Cigarette smoking is identified as a cause in multiple diseases including various cancers and respiratory conditions. Measuring the prevalence of tobacco use can alert communities to potentially adverse health outcomes and assessing the need and effectiveness for/of cessation programs.

Ozone Days: Ozone days are the annual number of days that air quality is unhealthy for sensitive populations due to ozone levels. The relationship between elevated air pollution - particularly ozone - and compromised health is a reality. The negative consequences of air pollution include decreased lung function, chronic bronchitis, asthma, and other adverse pulmonary effects.

Particulate Matter Days: The air pollution particulate matter (PM) days is the annual number of days that air quality is unhealthy for sensitive populations due to fine particulate matter (FPM, < 2.5 micrometers in diameter). The relationship between elevated air pollution - particularly PM - and compromised health is a reality. The negative consequences of air pollution include decreased lung function, chronic bronchitis, asthma, and other adverse pulmonary effects.


Asthma Prevalence: Lifetime asthma prevalence is the proportion of people in a population who've ever been diagnosed with asthma by a health care provider. Prevalence helps us understand the impact of asthma on a society and our health care system. In addition, prevalence allows us to identify which populations are disproportionately affected and where prevention and intervention efforts should be directed.

Asthma Prevalence, ages 5-17: Asthma prevalence for children is the proportion of children in a population, asked the question, through their parent/guardian, "Has a doctor ever told you that your child has asthma?" Asthma is the most common chronic disease in childhood. Asthma can be particularly difficult for children and their families as it may limit the child's ability to play, learn and sleep and can require costly interventions. Nationally, the prevalence of asthma among children has been increasing, and is higher than prevalence in adults.

Asthma Emergency Department Visits: Asthma related Emergency Department (ED) visit data includes rates of visits to an ED because of asthma (number per 10,000 residents). A visit to the emergency department is often an indication of inadequate long- term management of asthma or inadequate plans for handling exacerbations. With proper health care management, the majority of emergency department (ED) visits for asthma are preventable.

Asthma Hospitalizations: The average rate of hospitalizations (admissions and discharges) due to asthma (number per 10,000 residents). Inpatient hospitalizations are one of the most serious consequences of asthma both in terms of personal costs to affected individuals and associated medical costs. Asthma hospitalizations are considered to be almost wholly preventable with appropriate asthma treatment and trigger avoidance. Inpatient hospitalizations represent the largest portion of direct medical expenditures for asthma. Asthma hospitalizations are an important surveillance endpoint because they help identify populations where prevention efforts can best be directed. Examination of hospitalization rates can also provide a useful estimate of the direct medical costs associated with poorly-managed asthma.


Overall Poverty: Percentage of individuals in an area at or below poverty (quartiles). Poverty contributes to poor health. Poverty forces people to live in environments that make them sick, without decent shelter, clean water or adequate sanitation.

Children in Poverty: Children in poverty is the percent of children under the age of 18 living below the Federal Poverty Line (FPL). Poverty can result in negative health consequences (ex. such as increased risk of death, depression and poor health behaviors). Children in poverty have greater risk of accidental injury and lack of health care access.


Technical terms

Confidence Interval: A confidence interval indicates the reliability or uncertainty surrounding an estimate. We present 95% confidence intervals - this means that the true value lies within this range 95% of the time. Smaller confidence intervals indicate that an estimate is more precise or reliable.

Age Adjustment: This is a tool used to account for the different age distributions of the population. Age adjustment enables populations (e.g., counties) with dissimilar age distributions (e.g., high percentage of elderly residents) to be compared with other counties. Age adjustment to the same standard population allows meaningful comparisons of vital rates over time and between geographic areas and population groups.