Reducing Our Risk

Hennepin County Emergency Management

Medina, MN, USA
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An Overview Of Our Solution

Disaster Preparedness Goal:

To protect human life by helping the NWS enhance their heat advisories and warnings. Enhanced advisories and warnings would lead to earlier messaging to vulnerable populations, reducing heat stress injuries in athletes, those who work outside, as well as people who serve the public (police, fire, EMS etc.).

Which Hazard from above are you addressing?

Extreme Temperature: Heat

What are you doing to reduce the risk?

Hennepin County Emergency Management has installed Wet Bulb Globe Temperature (WBGT) sensors to measure the effects of solar radiation.

Who is this solution impacting?
Ecosystem
Urban Built Environment
Urban/Built Environment
Community Type
Urban
Urban
Additional Information
  • Population Impacted: 1.2 Million
  • Continent: North America
General Info

Address

1600 Prairie Drive
Medina, MN 55340
United States

Email

eric.waage@hennepin.us
Problem

Hazard

Extreme Temperature

Identify the likelihood and frequency of this hazard

In the past 10 years, Hennepin County (HC) Minnesota has recorded 60 days with Heat Indices over 90 degrees Fahrenheit. Heat indices over 90 degrees is where the National Weather Service (NWS) describes people should take extreme caution when outside or doing an extraneous activity as they are at risk for heat illness. With high temperatures and humid climate during summer months, Hennepin County expects extreme heat conditions annually if not multiple time each year.

Explain how vulnerable the community is to this hazard

Urban and suburban areas are at greater risk for extreme heat due to the urban heat island effect. Urban heat islands are large metropolitan areas that are warmer than surrounding rural areas because of pavement, blacktop, and buildings. The University of Minnesota conducted a study showing the Twin Cities metro area temperature differences in 2011. HC is the largest county by population in Minnesota with large urban and suburban populations which makes us extremely vulnerable.

List the potential affects of this hazard

Extreme heat has been referenced as a silent killer because extreme heat doesn’t immediately impact people when it sets in. Heat strokes are the most serious of heat illness which can cause death or permanent disability. Heat stroke occurs when the body becomes unable to control its temperature. Heat exhaustion, another heat illness, is the body’s response to loss of water and salt seen during exercise, in elderly, or in those working in hot environments.

Identify how sensitive the community is to these affects

Hennepin County is extremely sensitive due to the Urban Heat Island mentioned earlier as Minneapolis, one of the cities that makes up the Twin Cities, is located in Hennepin County. In addition, we have 22 independent school districts, many without air conditioning, large elderly population, and a large homeless population.
Action

Preparedness Goal

ie - What did you do to reduce this risk?

Implementation Actions

Hennepin County Emergency Management has installed four WBGT sensors around Hennepin County and expects to have two additional sensors installed by May 2015. Currently, the NWS issues heat advisories and warnings based on the Heat Index. The Heat Index takes the actual temperature (measured in the shade) and combines it with the humidity to create a number that reflects what temperature ‘feels’ like outside. However, one is not always in the shade when outside in extreme heat conditions. This is where the WBGT shows a better indication of the heat stress because it takes into account temperature, humidity, wind speed, sun angle, and cloud cover (solar radiation). These additional parameters are the key factors that need to be taken into consideration with how the temperature feels on our bodies, how our body reacts to heat, and how efficient our body is at cooling itself.

The WBGT has been used for many years amongst military and marathon organizations. To this day, there is no permanent network of WBGT sensors to aid in the initiative of advanced advisory and warnings. Hennepin County Emergency Management and the NWS Twin Cities have realized the importance of this WBGT technology and have partnered to begin creating a network of these sensors. We feel the effects of solar radiation when we choose to wear a white shirt outside on a hot sunny day rather than black.

Since many workplaces currently use the Heat Index as an indicator for work/rest ratios, or how long individuals can work outside, a training program is also needed to be implemented to show the importance and innovative information now available to the public, but also how to interpret the new information as the numbers given by the WBGT data, will be different than the current heat index.

Solution

Describe Your Solution

The combined efforts of installing these WBGT sensors, and working with the NWS to enhance their extreme heat advisories and warnings will reduce the risk of extreme heat related illnesses by being able to communicate the true effects of the sun on the human body and how it ‘feels’ to the public who are outside.  One example is for athletic directors of schools can revise their districts heat stress policy to include work/rest periods based on guidelines from the WBGT readings. This may be that coaches adjust their practices times, or include additional water and shade breaks into their athlete’s workouts.  This can also be the case for employers that have outside duties or trainings for their employees (eg. Firefighter training in full gear). An additional way this network of sensors reduces heat illness risk is it will allow cooling centers to open under new criteria that better represents the heat stress on our bodies which will be beneficial for our homeless population.

The information collected will be available to the public for free on a website. This way they will be able to see current up to date readings, along with the impacts/safety recommendations (consistent with the NWS) for themselves whenever they want. If they have experienced a heat illness in the past, and wish to set more strict guidelines for themselves, they are able to do that because this information will be free and available 24 hours a day 7 days a week.

Results

Economic?

The WBGT sensor network is part of a larger weather related initiative by Hennepin County called the Hennepin West Mesonet. It was/is economic for us to build out a WBGT network at the same time we are building out the mesonet.  Since the information is completely free for anyone that wishes to use it, they are able to keep themselves safe with not only heat related information, but all aspects of weather related information without having any cost to them.

Environmental?

There are minimal impacts to the environment beyond putting the equipment up. The majority of the sensors are co-located with other weather sensors so there are not additional disturbances to the environment.

Social?

Research has shown that in disaster situations, people are more likely to act in a calm and organized manner when they have plentiful information available for them to make educated decisions.  Although, as mentioned, heat illnesses due to extreme heat situation tend to take longer to show, by having the WBGT network available, people are able to make the best educated decision for themselves and they are able to help their relatives, neighbors, and friends as well.

What were the negative or unintended impacts (if any) associated with implementing this solution?

At this point we have not had any negative impacts. One impact we do expect that could be considered negative is the WBGT sensors give a number that is lower than the current Heat Index value because it is measuring additional components of the environment. This might be confusing to the public which is why we are working toward implementing a training program to go along with the impacts/safety recommendations.

Replication/Scale

Return on Investment: How much did it cost to implement these activities? How do your results above compare to this investment?

Each sensor system cost about $3,800. FEMA has noted that the cost of a human life when a disaster hits is about 1.74 million dollars. If we are able to save even just one person’s life with the information we are able to give with this network, we have saved more than we have put into it. In addition, with these sensors will also help to reduce heat stress injuries for Minneapolis employees such police, fire and public works departments who consistently work outdoor operations, cutting needed time off for employees and better production during periods of work time.

What are the main factors needed to successfully replicate this solution

The main factor in order to successfully replicate this solution is have the ability to buy the equipment and work with the local National Weather Service Office. By working with the local National Weather Service Office, they will be able to implement the data gathered from the local area as opposed to estimation from other data gathered.

Overview
Problem
Results