Heat Illness Metadata: Near Real-Time Emergency Department Visits


Near real-time emergency department visit data for heat illness are from the Maine CDC Infectious Disease Program’s syndromic surveillance system.

Dates Available: 

2017 to date

Geographic Resolution: 

State, County


The Maine EPHT program receives daily counts of emergency department visits for heat illness from syndromic surveillance data collected by the Infectious Disease Program at the Maine CDC. The dataset contains the following measures:

  1. Number of heat illness emergency department visits, by week and day, Statewide and County.
  2. Percent of heat illness emergency department visits, by day and day, Statewide and County.

County data are available by the patient's county of residence (residence), and the county in which the patient received treatment (hospital).


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 cold-related illness incidence across the state, and over time. 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: 

The Maine CDC Infectious Disease Program operates a near real-time “syndromic surveillance” system. Syndromic surveillance is the collection and analysis of medical data in near real time to detect health events such as disease outbreaks, exposures, and bioterrorism. The Maine CDC system receives emergency department visit information directly from all hospitals in Maine, conveyed one or more times per day via secure, electronic messaging. The Maine CDC searches relevant fields in each record, including the chief complaint, reason for visit, and discharge diagnosis, for key words or codes, and categorizes the visit record into defined syndromes or events. “Heat illness” visits are defined as any visit with a heatd illness diagnostic code, or where the chief complaint field includes the text string “hyperthermia”, “heat stroke”, “heat exhaustion,” or related terminology, while excluding non-heat illness-related strings such as “infection" and "feels hot". U.S. CDC's Morbidity and Mortality Weekly Report (MMWR) publishes data using a nationally consistent definition of "week". This is known as the MMWR week. Most years consist of 52 weeks, but sometimes a year can have 53 weeks. Each week contains seven days (Sunday through Saturday). The first week of the year does not always start on January 1st and may begin in the prior year. Maine residents and non-Maine residents seen at Maine hospitals are included in these data when the data are displayed by hospital. Data displayed by patient residence include Maine residents only.

Entity and Attribute Overview: 

The dataset includes the following fields: Date, week number (MMWR week), state of residence, sum and percent of heat illness emergency department visits.

Data Limitations: 

Automated coding is imperfect and will include some non-heat illness emergency department visits, while also excluding some true heat illness emergency department visits. Spelling variations and alternative terminology can result in heat illness visits that are excluded (false negatives), while the broad syndrome definition of “heat illness” can include some visits that are not related to environmental exposures (false positives). Data are considered preliminary and subject to change.

Access Constraints: 


More Information: 

Suggested Citation for Data Displays: 

Maine Center for Disease Control and Prevention, Maine Tracking Network. Heat Illness: Near Real Time Emergency Department Visits. Available online: https://data.mainepublichealth.gov/tracking/. Accessed on [date accessed].

Contact Information:

Maine Environmental Public Health Tracking Program
Maine Center for Disease Control and Prevention
Environmental and Occupational Health Programs
286 Water Street, 9th Floor, 11 State House Station
Augusta, ME 04333-0011
United States of America

Voice: 866-292-3474 (toll-free in Maine) or 207-287-4311

TDD/TTY: 711

Fax: 207-287-3981

Email: metracking@maine.gov