Carbon Monoxide Metadata: Emergency Department (ED) Visits


Emergency Department (ED) visit data are from the Maine Health Data Organization (MHDO). Population data are from the U.S. Census Bureau.

Dates Available:

2001-2014, 2016-2020

Geographic Resolution:

State, Public Health District, County


The Maine EPHT program receives ED data annually, based on discharge date, from MHDO. Carbon monoxide (CO) related ED visits among Maine residents are analyzed, and categorized as fire-related, non-fire-related, and unknown cause. The data are stratified by admission year, geographic resolution, age group, and sex.

The dataset contains the following measures:
1. Crude rate of ED visits for CO poisoning per 100,000 population.
2. Age-adjusted rate of ED visits for CO poisoning per 100,000 population.
3. Number of ED visits for CO poisoning.


This data set supports efforts to improve public health in Maine and contributes to the U.S. CDC’s National Environmental Public Health Tracking (EPHT) Network. A key activity of participants in this network is to track and make available environmental health measures on state and national data portals. Measures derived from the data set described here can be used to compare CO ED visits across the state, between groups of people, over time, and in relation to risk factors, exposures, and health outcomes.

The Maine Tracking Network, a member of the National EPHT Network, connects communities, public health professionals, policy makers, state agencies, and others to the data they need to monitor public health, respond to health concerns, prioritize resources for public health action, and evaluate prevention activities. Maine tracks certain health effects, exposures, and environmental hazards that have known relationships, as well as some health effects and environmental hazards that have suspected relationships. By making health and environmental data available through the Maine Tracking Network, more people have access to data they need to think critically and hypothesize about health outcomes and their relationships to conditions in the environment.

Supplemental Information:

Maine tracks ED visits, hospitalizations, and deaths due to CO poisoning, as well as the prevalence of CO detectors in Maine homes. Taken together, . Combined, these measures are used to plan and evaluate prevention efforts and track the impact of public health policy aimed at preventing carbon monoxideCO poisoning.

CO ED visits are selected based on discharge diagnosis coding (ICD9-CM ) of primary, and all secondary, diagnoses. The Maine EPHT Program receives calendar year inpatient hospitalization data, and outpatient data, annually from the Maine Health Data Organization (MHDO). Data have been de-identified to protect confidentiality.

On October 1, 2015, diagnostic coding switched from the International Classification of Diseases, 9th Edition, Clinical Modification (ICD-9-CM) to the 10th Edition (ICD-10-CM). ICD-10-CM is substantially different from ICD-9-CM, and differences in coding guidelines could alter the classification of diseases. For this reason, changes in the magnitude of a count or rate might, in part, be attributed to changes in the coding schema rather than underlying risk factors. Emergency department data for 2015 are omitted due to the change in coding practices that occurred during that year.

Entity and Attribute Overview:

This dataset contains the following fields: admission year, geographic resolution, measure, sex, age group, count, population, rate per 100,000, 95% confidence intervals for rate, age-adjusted rate, 95% confidence intervals for age-adjusted rate.

Data Limitations:


  • Only Maine residents admitted to Maine hospitals are included in the analysis. Neither Maine residents who received care outside of Maine, nor visitors to Maine who received care in Maine, are included.
  • Data represent the number of ED visits, by admission date, for CO poisoning. The data do not represent the number of individual people hospitalized, nor the burden of disease in Maine.
  • Approximately one third (1/3) of emergency ED visit records did not contain e-codes. Since e-codes are used to identify exposure intent (i.e. suicide, homicide), source (i.e. fire relatedness) and setting (i.e. workplace), the ability to accurately identify whether a visit is unintentional and non-fire related is limited.
  • 2015 data are not included because diagnostic coding transitioned from the International Classification of Diseases, 9th Edition, Clinical Modification (ICD-9-CM) to the 10th Edition (ICD-10-CM) in October 2015. Counts and rates before 2015 are based on different coding definitions than after 2015. Additional attention is advised when comparing counts and rates before 2015 to counts and rates after 2015.

Access Constraints:

Publicly available data are suppressed in accordance with the Maine CDC Privacy Policy to protect confidentiality.

More Information:

Suggested Citation for Data Displays:

Maine Center for Disease Control and Prevention, Maine Tracking Network. Carbon Monoxide PoisoningMetadata: Emergency Department (ED) Visits. Available online: Accessed on [date accessed].