Heat-related Illness

Heat illness can be mild or it can be severe, at times requiring medical attention. Tracking emergency department visits and hospitalizations due to heat-related illness can be used to understand how Mainers are affected by hot weather. Maine uses survey data to track air conditioning access because spending time in air conditioning is often the best prevention against heat-related illness.

What data are available?

Maine tracks the following measures associated with heat-related illness:

Near-real time data (daily emergency department visits)
Emergency department (ED) visits (annual summaries)
Hospitalizations
Air Conditioning (A/C) Access

Heat-related Illness Emergency Department Visits

This display shows the number and rate of heat-related illness emergency department (ED) visits per 100,000 population. These data can tell us which counties have a higher number or rate of ED visits and if a rate is going up or down over time. To add a county to the trend chart, click a county on the map. To unselect a county, click the same county again.

Heat-related Illness Hospitalizations

This display shows the number and rate of heat-related illness hospitalizations per 100,000 population. These data can tell us which counties have a higher number or rate of hospitalizations and if a rate is going up or down over time. To add a district to the trend chart, click a district on the map. To unselect a district, click the same district again.

Air Conditioning Access

This display shows the number and percentage of adults who have access to air conditioning as reported through the Behavioral Risk Factor Surveillance System, a telephone survey. Data is based on a yes response to "Do you have any type of air conditioning in your home?" To add a district to the trend chart, click a district on the map. To unselect a district, click the same district again.

Heat-related Illness Trends

This display shows trends over the years in heat-related illness emergency department (ED) visits and hospitalizations. These data can tell you if a segment of a population (by sex or age) is at higher risk for a visit to the ED or hospitalization for heat-related illness.

Heat-related Illness Tables

Create a custom table of data about heat-related illness emergency department (ED) visits, hospitalizations, or air conditioning access.

Measure Definitions

Near Real-time Emergency Department Visits and Temperature
- Near real-time heat-related illness data are from Maine’s syndromic surveillance system, which gathers and aggregates data from emergency department visits from hospitals in Maine. Visits are counted as heat-related based on a syndrome definition that uses a combination of keyword searches of a patient’s chief complaint along with relevant diagnosis codes.
- Temperature data are supplied by the Maine Climate Office at the University of Maine’s Climate Change Institute (https://mco.umaine.edu). The daily minimum and maximum temperatures represent the lowest AM and highest PM values within each day. Apparent maximum and apparent minimum are the “feels like” temperatures which account for humidity and wind speed. Temperature data are population weighted, to best represent population exposures.
- Heat-related illness visits are analyzed by county of residence (where the patient lives) and county of care (where the patient was treated). Place of residence analyses are restricted to Maine residents, whereas place of care analyses include anyone who was treated at a Maine facility. Percentages represent the number of heat-related visits compared to all emergency department visits, which allows for comparisons while accounting for population or utilization differences. Sagadahoc county does not have a hospital and does not show on the map when data are shown by place of care.

Emergency Department Visits and Hospitalizations
- Visits with a primary or secondary diagnosis of heat-related illness (e.g. heat stroke) are included in the analysis.
- Hospitalization 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. Caution is advised when comparing rates in years before 2015 to rates in 2016 and later due to the coding change.
- Analyses are based on the year of admission to an emergency department or hospital.
- Heat-related illness visits are analyzed by place of residence (where the patient lives) and place of care (where the patient was treated). Place of residence analyses are restricted to Maine residents in order to calculate rates per population. Place of care analyses are not restricted to Maine residents, and only displayed as counts (Number). Use place of residence to compare rates across the state. Use place of care to view the burden (total number) of heat-related illness visits.
Air Conditioning Access
- Air conditioning data are from the Maine Behavioral Risk Factor Surveillance System (BRFSS), a random-digit-dial telephone survey of non-institutionalized Maine adults ages 18 years and older. Estimates are based on a positive response to the question “Do you have any type of air conditioning?”

Data Limitations

Near Real-time Emergency Department Visits and Temperature
- Syndrome definitions using key words are imperfect, and occasionally include non-heat-related visits or mistakenly exclude heat-related visits.
- ED visit data do not include visits to the Veteran’s Affairs hospital in Maine or the Indian Health Service.

Emergency Department Visits and Hospitalizations
- Visits associated with Maine’s Veteran’s Affairs Hospital and the Indian Health Service are not included.
- Only Maine residents seen at Maine hospitals are included when data are analyzed by place of residence. Out-of-state residents are included when data are analyzed place of care.

Air Conditioning Access
- Maine adults who are institutionalized, do not have a phone, or are unable to communicate are not represented.
- Statistical weights are used to calculate prevalence estimates in order to be more representative of the general adult population in Maine and to adjust for non-response, though weighting methods are not perfect in accomplishing this. In 2015, weighting methodology changed to include cell phone and landline respondents. Changes in prevalence estimates may be partially related to changes in weighting practices.

Additional Details

In order to protect privacy as per the Maine CDC Privacy Policy, data may have been suppressed. For locations where data must be suppressed a range (e.g. 1-5) is provided for the number of events and an asterisk (*) for the rate. Data may be secondarily suppressed to prevent indirect identification and displayed as not reported (NR).
Age-adjusted rates are considered unreliable and not reported (NR) when case counts are less than 25.
Combined year population data are the sum of individual years (e.g., 2010-2014 is the sum of populations in 2010, 2011, 2012, 2013, and 2014). Combined year rates are annualized across all included years.

Environmental Public Health