Maricopa County (MC), Arizona experiences extreme weather, including heat waves, dust storms, drought, wildfires, flooding, and poor air quality events. These climate-sensitive hazards pose a threat to public health and can lead directly to illness, death, or worsening underlying health conditions. Maricopa County Department of Public Health (MCDPH), Office of Epidemiology has been conducting heat-associated morbidity/mortality surveillance since 2006, and extreme heat has become a public health priority as temperatures continue to rise. To combat the health risks associated with rising temperatures, the Maricopa Association of Governments (MAG) and the City of Phoenix formed the Heat Relief Network (HRN) in 2005. This collaborative created an innovative system of community cooling centers and water distribution stations throughout the county (Heat Relief Regional Network).

MC in Arizona is located in one of the hottest regions in the southwest. Over 4 million people (62% of the state’s population) reside in MC. The Phoenix metropolitan area is located at its center and includes more than 20 municipalities and three tribal communities. Each year, MC experiences extreme temperatures and continues to experience two to three weeks (cumulative) of excessive heat warnings issued by the National Weather Service. These temperatures result in an average of 100 heat-associated deaths each year. However, over the last three years, heat-associated deaths exceeded 150 each year (Graph 1) and the number of heat-associated injuries exceeded 2,000 each year.

Nearly 40% of these deaths occur indoors. Despite more than 90% of MC homes having an indoor cooling system, people are still at risk for adverse health outcomes as a result of extreme heat in their homes. People at highest risk of dying indoors tend to be elderly individuals and those with chronic medical conditions partly. High temperatures also disproportionately affect other vulnerable populations including people of color and those experiencing poverty or homelessness, who may not have easy access to air conditioning and the cooler indoors. In MC, heat-related death rates were highest among people aged 75 years and older (8.1 per 100,000 residents), people aged 65 – 74 years (3.7), Native Americans (4.1), and African Americans (3.1). African Americans aged 75 years and older had the highest death rate of any age and race/ethnicity group within the county (37.4 per 100,000 residents). To view more statistics by year, trends over time and heat deaths by geography, check out this ESRI MAP developed by the Office of Epidemiology.

Measuring the Effects of Heat on Public Health

The Office of Epidemiology at MCDPH uses a data-driven approach to identify risk factors for heat-related deaths and injuries. A key component was a survey of the community to learn about community behavior, heat perception, and access to cooling systems.

Using data collected after death, we identified that older individuals who died from heat were more likely to be indoors than outdoors. The vast majority (87%) of those who died indoors of heat-related causes were not using an air conditioning (AC) unit at the time of death. For 61%, the AC unit was not functional; for 11% there was no electricity; and for 28%, either the AC unit was turned off or the reason was unknown.

To better understand the underlying cause for lack of functioning AC and to identify the unknown reasons for lack of AC in the death data, we conducted several heat-related surveys. In 2014, MCDPH conducted the Cooling Center Evaluation project in collaboration with community partners and educational stakeholders. For this evaluation, we interviewed individuals who visit cooling centers. From the visitor survey, we learned that 27% of respondents had an inoperable AC unit or could not afford to operate AC. 65% indicated they were aware of utility assistance programs, but had not applied. 10% were unaware of utility assistance programs (Maricopa County Cooling Center Evaluation Project” Visitor Survey Results).

In April 2015, we conducted a Community Assessment for Public Health Emergency Response (CASPER). The results of the CASPER found:

• An overwhelming majority of residents (94.5%) reported using central air conditioning to cool their house over the past summer.
• Among AC users, 7.2% reported using it during nighttime only, while 4.8% reported using it during daytime only.
• 10% of people felt too hot inside of their home “most of the time” or “always” during the previous summer.
• The top three reasons that prevented people from using AC were the cost of electricity (20%), a non-functioning AC (5%), or the cost of repairs (2%).
• Over 50% of respondents did not know that utility assistance services were available.

In 2016, we conducted a survey of homebound individuals focused on cooling systems in their homes to quantify their awareness and willingness to utilize community services. A majority of homebound individuals within our community (approximately 75% of respondents) felt too hot inside of their home “most of the time” or “always” during the previous summer. This is significantly higher than the response from the general population. The majority of homebound individuals reported having AC to cool their house (85%), however only (72%) reported that their AC is functioning. The top three reasons that prevented people from using AC were the cost of bills (81%), the cost of repairs (27%), or mobility limitations (17%).

These data gave us an opportunity to make a strong case to our partners and the community to highlight heat as a public health issue. Information from these surveys is shared with community members to assist in building prevention and intervention programs and actions.

Counter the public health effects of climate change by building partnerships.

The insight provided by the data has helped cultivate a series of long-standing partnerships focusing on heat and health between MCDPH and local governmental agencies, academia, and community organizations. Through surveillance information sharing, our partners have developed more targeted interventions. Examples of this include:

• The cooling center evaluation study provided information on cooling center service gaps in the community, and we have worked with our partners to develop expansion plans to address these gaps (Cooling Center Evaluation), which has led to the existence of triple the number of cooling centers in the county since the evaluation.
• The National Weather Service modified their heat advisories and heat-risk maps based on heat-related death data provided by public health (Heat Risk Map).
• Our partners promote awareness in the community about heat safety and availability of services.

Beyond heat, climate-related hazards are a public health concern.

The data we collected for heat-related deaths and injuries, not only helped to create partnerships and solidify heat as a public health concern, but also allowed for expansion to other climate-sensitive hazards.

In 2015, MCDPH Office of Epidemiology was awarded a grant from the Public Health Institute (PHI) to expand the focus from heat to climate change more generally. This grant provided the opportunity to join the Climate Change and Public Health Learning Collaborative for Urban Health Departments and receive financial support to incorporate climate change mitigation, adaptation, and resilience work into local public health department program practice.

As a part of this project, MCDPH worked with community stakeholders to host a series of meetings designated, Bridging Climate Change and Public Health (BCCPH). BCCPH convenes representatives from a diverse array of local community organizations, private businesses, government agencies, and academic institutions to discuss public health issues associated with climate change. These meetings helped identify local activities in the fields of climate and health, as well as stakeholders’ perceived needs of the community and barriers to successful collaboration.

In 2017, the CDC funded the Building Resilience Against Climate Effects (BRACE) project. This grant allowed us to develop a strategic plan with five priority actions (Bridging Climate Change and Public Health strategic plan) for addressing environmental concerns affecting the health and well-being of the community.

We have been working in this area since 2005 and our experience has allowed us to join other efforts locally and nationally. Locally, we became core participants in The Nature Conservancy’s (TNC) Nature’s Cooling Systems project to design urban heat solutions in the Valley of the Sun. In addition, we closely collaborated with staff of the Institute for Sustainable Communities, which was instrumental in helping build our partnership capacity, and we recently we joined The Rio Reimagined project workgroup. Nationally, MCDPH, in collaboration with Columbia University and the American Council for an Energy Efficient Economy, will begin conducting research to understand the public health impact of energy insecurity.

Addressing the impact of heat on health is well-aligned with MCDPH’s vision and mission “to make healthy lives possible” by protecting and promoting the health and well-being of MC residents and visitors. The climate has significant impacts on our community’s health. Through extensive surveillance and community surveys, we have demonstrated the importance of local public health data to increase buy-in from new and existing partners and obtain funding to address this significant public health issue. We encourage other health departments to consider the power of data and collaboration as they seek methods for protecting the public’s health from a changing climate.