CO Poisoning

Definition of Reported Measures 

  • Hospitalizations due to Carbon Monoxide (CO) Poisoning represents California residents who are hospitalized due to CO poisoning; expressed as a rate per 1,000,000 California residents.
  • Emergency department (ED) visits due to Carbon Monoxide(CO) Poisoning represents California residents who visited an ED due to CO poisoning; expressed as a rate per 1,000,000 California residents

How to Read Tables, Charts, and Maps 

  • The 95% confidence interval (CI) is the range of values that likely contains the true rate in the population.
  • Conventional rates express the number of outcomes relative to the size of the population.  N/A indicates that the data are not available due to the number of events being less than 12.
  • Total counts per year are listed next to conventional rates unless the total number of events is less than 12. For hospitalizations, years are aggregated and Total refers to the average counts per year. 
  • Some counties have a greater proportion of people who are old or young than other counties, which makes it difficult to compare across counties or over time. Scientists often fix this problem through a technique called age adjustment so comparisons can be made. In addition to crude rates, we also present age-adjusted rates.
  • Effective October 1, 2015, hospital record (OSHPD) data transitioned from ICD-9 to ICD-10-CM. Differences between counts and rates in years prior to 2015 compared with 2015 and subsequent years could be a result of this coding change and not an actual difference in the number of events. 

Data Sources

  • Emergency Department and Patient Discharge Datasets from the State of California, Office of Statewide Health Planning and Development (OSHPD). 
  • Denominators for rates are based on estimates from the California Department of Finance.


  • Patients meeting the CSTE case definition for a confirmed or probable case of acute CO poisoning. Intentional poisonings are excluded.  

Limitations of the data

  • Data Collection Purpose- Diagnosis codes are recorded by hospitals for reimbursement purposes and not for public health surveillance.  
  • Low-level of resolution- Hospitals are not mandated to report patient addresses.  The level of geographic resolution of the data is limited to state, county, and zip code.
  • The toxic effects of CO exposure are nonspecific and easily misdiagnosed when CO exposure is not suspected. These misdiagnosed cases will not be counted.

Suggested Citation

Tracking California, Public Health Institute. Carbon Monoxide Related Emergency Department & Hospitalization data. Accessed [Month/Day/Year] from

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