Heat Early Warning Systems. Karen Smoyer Tomic, PhD HealthCore and Department of Geography, University of Delaware

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1 Heat Early Warning Systems Karen Smoyer Tomic, PhD HealthCore and Department of Geography, University of Delaware

2 Understanding Heat Health Warning Systems What is a heat health warning system (HHWS)? How does a HHWS work? How and Where are they being used? How effective are HHWS? What should we expect for HHWS in the future?

3 What is a HHWS? A public health warning system that uses meteorological forecasts to predict the likelihood of hot weather conditions that are expected to have serious adverse health impacts May or may not include specific public health interventions

4 HHWS Epidemiologic Surveillance Objective is to find the signal (health impact caused by heat) in the noise (background health impacts due to other factors) Need to consider exposure (weather event) and health impact (e.g., mortality, ED visits, hospital admissions, EMR calls) Type of active surveillance (searching for a pre-specified health signal associated with a known exposure)

5 Heat Health Impacts Pyramid Mortality Severity of Effect Hospital admission Medical seeking behavior: emergency room, physician s office, clinic, EMT Heat cramps, heat exhaustion, heat stroke Mild symptoms, discomfort, subtle effects (e.g. skin eruptions, heat fatigue) Source: Bassil et al Proportion of Population

6 HHWS Factors for Consideration Expected health impact is serious (death, heat stroke capable of irreversible organ damage, etc.) Trade off between requiring actual health impact (ED visits, EMR call) which may be too late versus using predicted health impact associated with given hot weather exposure Long record of heat/health studies solid evidence for estimating health (mortality) impacts associated with hot weather on given populations and places

7 How does a HHWS work? Define harmful exposure Identify unacceptable level of risk Establish warning criteria Design an intervention plan Develop and test system Implement, evaluate, and re-set parameters as needed

8 Issues in developing a HHWS How will exposure (hot weather) be defined? What health impact(s) should be used? How big a difference in actual or expected health impact is needed to trigger an alarm? What level of statistical significance is to be used?

9 HHWS Systems have at 2 major components Weather Forecast/Parameters forecast (univariate, bivariate, multivariate index) action criteria for heat warning or emergency (thresholds, probability of deaths, etc.) Other variables (timing, duration of conditions) Public Health Intervention Disseminate warning (how, to whom?) Action plan (increased health care, education campaigns, cooling shelters, utilities not cut off, power backup, special intervention for vulnerable populations and places)

10 Appropriate intervention is essential in HHWS Reactive: respond to heat after a warning is issued (education, cooling shelters, home-visits/check-ins, increased health services) Proactive: prepare year-round, limit exposure (distribute AC to at-risk before summer season, increase green space/ light colored materials)

11 Intervention types Behavioral modification Focus on individual Requires individuals to change behavior/take action May be low cost but success may be limited Environmental modification Policies prohibiting or encouraging actions Changes in physical or built environment Can be expensive and time-consuming but may be more successful in desired health outcome

12 Public Health Education Campaigns

13 Environmental Modification Raise the Albedo, Add Vegetation

14 How Do HHWS work? Example from the field - Philadelphia Began after 1993 heat wave responsible for 115 deaths. Part of Department of Public Health, coordinated by Division of Health Promotion Uses Kalkstein and Sheridan s air massbased spatial synoptic classification HHWS

15 Philadelphia HHWS Includes prevention and education before heat waves Intervention/mitigation include using block captains as part of buddy system to check on at-risk individuals Increased EMS staffing Service (utilities) suspensions halted Heatline Relatively low cost to implement (some activities are already being done; others require extra funding for staff time) Source: Ebi et al BAMS

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17 HHWS developed by L. Kalkstein et al, Synoptic Climatology Lab USA International Chicago, IL Dayton/Cincinnati, OH Dallas/Fort Worth, TX Detroit, MI Houston, TX Jackson/Meridian, MS Lake Charles/Alexandria, LA Little Rock/Pine Bluff, AR Memphis, TN/Tupelo, MS Minneapolis, MN New Orleans/Baton Rouge, LA Washington DC/Baltimore, MD Philadelphia, PA Phoenix, AZ Portland, OR St. Louis, MO San Francisco/San Jose, CA Seattle, WA Shreveport/Monroe, LA Yuma, AZ New York, NY Los Angeles, CA Oklahoma City, OK Kansas City, MO/KS Italy: Bari Bologna Florence Genoa Milan Naples Palerma Rome Torino Canada: Brampton/Caledon/Mississauga Toronto Seoul, Korea (+6 additional cities) Shanghai, China

18 Does one HHWS fit all? City-specific needs Population (elderly, isolated, low income, ill) Place (high heat load, high crime, low service) Sector-specific needs public health utilities transportation emergency planning Two-tiered or targeted systems

19 HHWS Considerations Two-Tiered Warning General Alert High-Risk Area Alert city/suburb vs within city Targeted Intervention High-Risk Populations High-Risk Places Mobile teams Cooling shelters at familiar sites

20 Examples from St. Louis 1980 heat wave City not prepared 113 reported heat deaths Unknown number of excess deaths Impetus for HHWS (Operation Weather Survival) Not all areas of city equally affected

21 Heat exposure is not evenly distributed

22 Vulnerability involves exposure and sensitivity. Where do they overlap?

23 Potential High-Risk Housing with Moderate Socio-Demographic Risk

24 Mortality is not evenly distributed during heat waves

25 Factors in Targeting Heat Warnings and Interventions Urban heat island (city/suburb) Microscale temperature variation Socio-demographic risk Housing type and equipment Accessibility to services

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27 Challenges in 2-Tiered HHWS Data Limitations Census tract or neighborhood-level health data Microclimatic temperature data Can use land use, remote sensing, or housing proxies Resource Limitations Funds Personnel

28 Research Developments that will benefit 2-Tiered HHWS Research on spatial vulnerability to heat Smoyer (1998); Harlan et al. (2006); Reid et al (2009/in press) Newest work includes: Socioeconomic and demographic information at tract or block level (from US Census) Remote sensing Land Use/Land Cover Building footprints

29 The Heat Risk Surface is Uneven The most effective warnings and interventions need to target high risk populations AND high risk places, especially where the two overlap.

30 Evaluating HWWS Difficult to control for heat wave severity What criteria should an effective HHWS satisfy? Many different types of HHWS (different exposure and impact criteria; different agencies involved, different interventions) Knowledge gap more research needed here, especially systematic external evaluation comparing different systems

31 Evaluation of PHHS system summers of Estimated 2.6 lives were saved on average, for each warning day and for the following three days. Based on # warnings called by Philadelphia Weather Service Forecast Office, watch warning system saved an estimated 117 lives over 3-summer period. In 2005, system identified heat events contributing to 21 of 22 heat fatalities. System flagged a mortality-inducing heat event 5 days out (July 18-20); not hottest event, but worst human impact of year. Source: Kalkstein presentation and summary of Ebi, KL, Teisberg, TJ, Kalkstein, LS, Robinson, L, Weiher, RF Heat Watch/Warning Systems Save Lives: Estimated Costs and Benefits for Philadelphia Bull. of the Am. Met. Soc. 85:

32 Challenges in HHWS Research shows that few individuals consider themselves at risk during heat (Mattern et al. 2000; Kalkstein, Sheridan, Kalkstein 2007) Those most at risk may be least likely to take protective action Response needs to be centralized, well planned, consistent, and able to mobilize quickly (Bernard and McGeehin, 2004)

33 Source: Kalkstein, Sheridan, & Kalkstein, Region of Peel Evaluation of Summer 2006 Heat Response (presentation)

34 HHWS as adaptation Is HHWS an effective adaptation? Behavioral vs. environmental modification both are needed More HHWS in more places expected Systems generally effective at forecasting dangerous heat events HHWS success depends on effectiveness of the intervention.

35 Adaptation can help beat the heat