MEASURE DESCRIPTION. Temperatures: Daily, Weekly, Monthly, Seasonally Diurnal Temperature Range: Daily, Weekly Unit:

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1 STATE ENVIRONMENTAL HEALTH INDICATORS COLLABORATIVE (SEHIC) CLIMATE CHANGE INDICATORS Category: Indicator: Environmental Indicators Maximum, Minimum, and Diurnal Temperature Measure(s): 1) Maximum Temperature 2) Minimum Temperature 3) Diurnal Temperature Range MEASURE DESCRIPTION Last updated: January 4, 2013 Time scale: Temperatures: Daily, Weekly, Monthly, Seasonally Diurnal Temperature Range: Daily, Weekly Unit: Degrees F Geographic scope: State and multi-state Geographic scale: Where monitors exist Background and Heat extremes can influence the economic, agricultural, manufacturing, significance: energy and infrastructure costs, as well as increase morbidity and mortality. In the United States, there are, on average, 400 deaths directly related to excessive heat 1. The true magnitude of temperature-related mortality could be even higher, since the primary cause of extreme heat related deaths is not consistently captured on the death certificate 1,10,11. It is known that infants, children under 1 year of age, and the elderly are considered at higher risk of mortality due to elevated ambient temperatures 1,12,13. Statistically significant increases in cardiovascular and respiratory mortality have been associated with extreme heat 5,3. Daily maximum and minimum temperatures have been used to evaluate the temperaturemortality relationship 18. In the Ramon et al. study of 50 U.S. cities, extreme heat increased mortality 5.74% from 1989 to Daily maximum temperature was used to define extreme heat; those days with a maximum temperature that exceeded the 99 th percentile were considered extremely hot 2. Another study by Lin et al. showed that for each degree above a pre-calculated temperature-health-effect threshold there was a 2.7%-3.1% increase in respiratory hospitalizations, and an increase of 1.4%-3.6% in cardiovascular hospitalizations 6. Aside from extreme temperatures, variations in sub-maximum temperature changes have been associated with other increases in morbidity and mortality rates 7,8 and with periods of at least 3 consecutive days of elevated temperature and humidity 9. Based on these reported findings, diurnal temperature ranges can be used to assess consecutive days of elevated temperature, as well as determine variation in temperature 18. Air temperature alone is not a sufficient indicator of heat stress 18. It has been estimated that over the past century, the overall global surface

2 Rationale: temperature has increased by F 17. Climate change is expected to have an impact on the occurrence of extreme temperature days and weather patterns. It is predicted that, in the future, climate change will increase the number of extremely hot days, and decrease the number of extremely cold days 8. As the U.S. becomes more urbanized, and the elderly population continues to increase 16, it is likely that heat-related morbidity and mortality will become an even larger public health concern than it is today. However, it is also anticipated that a series of technologic, infrastructural, and behavioral strategies could be implemented to mitigate the adverse consequences of ever-increasing heat on morbidity and mortality 8. These indicators may help us monitor trends in temperatures. This type of analysis could produce results that could be useful in the evaluation of public health policies and related intervention efforts. Diurnal temperature range is defined as the difference between daytime maximum and nighttime minimum temperature. On a weekly scale it is calculated as the difference between that week s maximum and minimum values. This measure will help monitor variation, and may more accurately identify unrelenting excessive heat, which is related to several adverse public health complications. Current predictions are that increasing ambient and apparent temperatures will create a growing public health concern. Minimum and maximum temperatures will capture temperature extremes. Thus, a maximum-minimum temperature indicator can be used as a precursor to the near-term occurrence of a heat hazard, and its associated public health consequences, which have been identified as increases in morbidity and mortality. The future linking of this proposed hazard heat indicator to adverse health outcomes may offer further benefits and insights. Because there is no widely accepted standard for assessing elevated ambient or apparent temperature, this temperature indicator will provide an easy to understand hazard measure of extreme heat. Maximum and minimum temperature values will be more sensitive in detecting temperature extremes than the information that can be extracted from average temperature 19. Limitations of measure: Daily temperature readings from weather monitoring stations are readily available and can be used to evaluate trends in temperature that occur temporally and spatially. Tracking these measures may help us to better understand evolving extreme temperature changes that can occur in the future, as a concomitant climate change event. One limitation of this temperature extreme indicator is that it does not include other known changes in criteria air pollutants, such as ozone or fine particulate matter. For this reason, this extreme temperature indicator will necessarily underestimate the additional contribution of air pollution on respiratory or cardiovascular chronic diseases due to extreme heat events. In addition, this extreme heat indicator alone cannot adequately measure extreme heat exposure because indoor temperature can be influenced by air conditioning, activity patterns, and other factors which are difficult to

3 quantify. Finally, a third limitation is that this indicator does not define what is considered an extreme temperature, a heat wave, or a heat hazard. Data source: Limitations of data source: NOAA- individual station data Monitors are available in some, but not all, locations in the U.S. Temperature monitors are usually placed in population centers or nearby airports. Thus, it will be difficult to capture variations in temperature extremes or changes in the heat index in places that do not have temperature monitors. Even though some small airports next to less densely populated cities do have temperature monitors, there a far more temperature monitors in large cities. This will present a bias in the temperature extreme data that may require correction by also using modeled temperature predictions. Related datasets: Additional data elements: Month of year Another limitation is that, because of equipment failure, there can be missing temperature readings even where there are temperature monitors. Additionally, there could be time lag between when data are recorded and when they become available for others to analyze. Comparative climatic data are often released 4-6 months following the end of each year, and individual station data are made available approximately 2-3 months after they are recorded. Descriptive statistical analyses of minimum and maximum temperature values and the diurnal temperature range may be acceptable at the beginning. But, in the future it may be necessary to use more advanced statistical methods to analyze the three proposed measures. ED data, Hospitalization data (NHDS), Vital Records (death records), Air quality data (e.g. ozone, particulate matter) Recommendations: 1. Since maximum temperature should be higher than minimum temperature for any given day, check and flag all negative values of Diurnal Temperature Range (DTR). 2. Check for outliers of both maximum and minimum temperature as well as outliers in DTR. An outlier as more than 4 standard deviations of the indicator. 3. Check the amount of missing data over time. Stations with more than 10% missing data may need to be excluded during analysis. References: 1 Basu, R and Samet, J Relation between Elevated Ambient Temperature and Mortality: A Review of the Epidemiologic Evidence, Epidemiologic Reviews, 24: Medina-Ramon M and Schwartz J., Temperature, Temperature Extremes, and Mortality: A Study of Acclimatization and Effect Modification in 50 United States Cities. Occupational Environmental Medicine, Epub ahead of print: PMID: Bhaskaran K et al Effects of ambient temperature on the incidence of myocardial infarction. Heart, 95(21):

4 4 Panagiotakos, DB et al Climatological variations in daily hospital admissions for acute coronary syndromes. International Journal of Cardiology, 94(2-3): CDC (Centers for Disease Control and Prevention) Impact of heat waves on mortality Rome, Italy, June-August MMWR Morb Mortal Wkly Rep, 53: Lin,S et al Extreme High Temperatures and Hospital Admissions for Respiratory and Cardiovascular Diseases. Epidemiology, 20: Basu R, High ambient temperature and mortality: a review of epidemiologic studies from Environmental Health, 8:40. 8 McGeehin MA and Mirabelli M The potential impacts of climate variability and change on temperature-related morbidity and mortality in the United States. Environmental Health Perspectives, 109(2): Saez M, et al Relationship between weather temperature and mortality: a time series analysis approach in Barcelona. International Journal of Epidemiology, 24: Donoghue ER, et al Criteria for the diagnosis of heat-related deaths: National Association of Medical Examiners. Position paper. National Association of Medical Examiners Ad Hoc Committee on the Definition of Heat-Related Fatalities. American Journal of Forensic Medical Pathology, 18: Shen T, et al Toward a broader definition of heat-related death: comparison of mortality estimates from medical examiners classification with those from total death differentials during the July 1995 heat wave in Chicago, Illinois. American Journal of Forensic Medical Pathology, 19: CDC Heat-related deaths four states, July August 2001, and United States, MMWR Morb Mortal Wkly Rep,51: Foroni M, et al A retrospective study on heat-related mortality in an elderly population during the 2003 heat wave in Modena, Italy: the Argento Project. Journal of Gerontology and Biological Science Medical Science, 62(6): Schwartz, J Who is Sensitive to Extremes of Temperature? Epidemiology, 16(1): NOAA. National Weather Service, National Weather Service Weather Forecast Office: Heat Index. < 16 Hobbs FB and Damon BL in the United States. Washington, DC: Bureau of the Census, US Department of Commerce 17 National Research Council Reconciling observations of global temperature change. Washington, DC: National Academy Press, Guest, C.S. et al Climate and mortality in Australia: retrospective study, , and predicted impacts in five major cities in Climate Research, 13: Perry, ML, Canziani, OF et al. Climate Change 2007: Impacts, Adaptation, and Vulnerability: Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, 2007

5 How-To-Guide Maximum and Minimum Temperature/Heat Index Accessing the data To access the data, NCDC NOAA has created a map interface for selecting the individual stations you would like data from. To select the appropriate stations follow these instructions: 1. Go to the NCDC NOAA National Climatic Data Center ( 2. Select Climate Data Online from the menu on the left hand side (see screenshot below) 3. On the Climate Data online page, select the Temperature map. (see screenshot below)

6 4. This should bring you to an interactive map that will allow you to select stations of interest. You can choose to review the different options explained in the Map Help window to learn how to utilize the different tools, but this is optional since the following instructions will take you step by step to your data. 5. Close the Map Help window. Change the basemap layer to Streets view. To do this, place your cursor over the button labeled Basemaps, a pop out will give you the option of selecting satellite view, hybrid view, streets view, topographical view, and relief view. We suggest using Streets view since this will make it easier to differentiate state borders and identify major cities. (see screenshot below)

7 6. Click and drag the map center it on your jurisdiction. Use the zoom scale bar to reach the scale that is most appropriate. 7. Each light brown dot on the map represents an individual data station. To select the stations for your jurisdiction activate the identify tool ( ) located in the tool bar at the top of the window. 8. A red outline will appear around the tool button to indicate that it has been activated. Using the cursor, click on a station you would like to collect data from. Once a station is selected, a pop up window will appear to show all the stations that may be located near the dot you clicked. (Note: Depending on the zoom scale certain dots may overlap one another on the map and so there may be multiple stations in the pop up window since a single dot may in fact be several dots overlapping one another.) Click the check boxes to select the stations to gather data from. Then click the Get Selected Data button

8 9. This will bring you to the NCDC NOAA database query page. 10. Select the appropriate dates to calculate weekly, monthly, seasonal, or diurnal temperature range. Click Continue. Click on the link to access the data in txt. format. 11. Repeat for all dates and stations needed for calculations. Then calculate the maximum and minimum temperatures for each time period (weekly, monthly, seasonal, diurnal) for the years of interest. It is up to you as to how many years you would like to collect data for it is suggested to collect data from 2000-present or most recent year available. Refer to the original indicator how-to-guide for dates that define each season (spring, summer, fall, and winter). Weekly Maximum and Minimum Temperature: a. Use the data obtained above. There is no week variable present, so the date of observation must be used to derive the number of week.

9 b. Produce a table that stratifies maximum and minimum temperature by week. The result should be only two temperature readings (the highest and lowest) per week. Monthly Maximum and Minimum Temperature: a. Use the data obtained above. b. Produce a table that stratifies maximum and minimum temperature by month. You may need to use the date to derive the month. The result should be only two temperature readings (the highest and lowest) per month. Seasonal Maximum and Minimum Temperature: a. Use the data obtained above. b. Produce a table that stratifies maximum and minimum temperature by season. Seasons will be defined as below based on the dates of the northern hemisphere equinoxes and solstices. Spring- March 20 th -June 20 st Summer- June 21 st -September 22 nd Fall- September 23 rd - December 20 th Winter- December 21 st - March 19th The results should include two temperature readings (the highest and lowest) per season. Diurnal Temperature Range (the most common indicator used in literature): a. Use the data obtained above. b. Produce a table that stratifies maximum and minimum temperature by day. The result should be only two temperature readings (the highest and lowest) per day. c. Daily maximum temperature - Daily minimum temperature = Diurnal temperature range.