Clark County Heat-mapping Project shows temperatures rise with development

A one-day heat-mapping project conducted last July found noticeable temperature variations across Clark County depending on building density and landscapes. The findings, presented Wednesday by Clark County Public Health staff to the county board of health, stem from the July 12 Heat Watch. About 50 volunteers from Public Health and Portland-based environmental consulting firm CAPA Strategies participated in the effort. Hotter temperatures were recorded in areas with dense development, while cooler temperatures appeared near parks and green spaces. “Buildings, roads and other paved surfaces without shade hold on to more heat than green spaces, and one really important factor in heat risk is where you live,” Amy Koski, built environment coordinator for Public Health, said Wednesday. “A better understanding of these areas in Clark County that have hotter or cooler temperatures based on the urban heat island effect or factors of the built environment can really help us better understand the impacts on health.” During the heat-mapping event, volunteers drove across 17 planned routes and collected approximately 102,000 temperature readings in the morning, afternoon and evening. Most of Vancouver, including downtown, Fourth Plain, Fruit Valley and the Orchards area; Washougal; downtown Camas; and downtown Battle Ground were the hottest areas in the afternoon. Cooler places during the afternoon included west and central Camas and the Burnt Bridge Creek Trail in Vancouver, according to Clark County Public Health. The data showed the hotter areas in the evening included Washougal and central and east Vancouver, particularly the Ogden, Bennington and Fisher’s Landing East neighborhoods. Cooler places in the evening included Ridgefield; La Center; areas north of Vancouver city limits, such as Mount Vista, Felida and Lake Shore; and northwest Battle Ground (Cherry Grove), according to Public Health. “I had the opportunity to be one of those volunteers out on campus. I did the morning and the evening,” Clark County Council Chair Sue Marshall said. “So I’m just fascinated with these maps and the difference in the time and how things change.” ‘An increasing health threat’ Extreme heat is the deadliest weather-related hazard nationally. In Washington, summers are getting longer and hotter, and heat waves are becoming more frequent, according to Amy Wilson, an epidemiologist with Public Health. Some populations are more sensitive to the health impacts of heat, including older adults, pregnant women, infants and children, and people with existing health conditions or who may take certain medications, Wilson said. “Some populations may be more exposed based on factors like where they live or work, and those include people living unsheltered or unhoused, people living in urban heat islands,” Wilson said. “Heat is becoming an increasing health threat in the Pacific Northwest.” When temperatures rise, the number of emergency department visits for heat-related illness in Clark County increases, according to Public Health. Between 2017 and 2024, there were more than 650 emergency department visits for heat-related illness at Clark County hospitals, Wilson said. Koski and Wilson encouraged the board of health to consider policies that reduce heat islands and promote community resilience, prioritize resource allocation for neighborhoods with increased vulnerability to heat, and support the expansion of energy assistance programs for cooling. Public Health does not have a future Heat Watch campaign planned, but it may revisit the possibility of another event after some changes have been implemented, Koski said. Clark County residents can prepare for hot weather by signing up for public alerts and monitoring weather and heat-risk forecasts during warmer months, Public Health said in a Wednesday news release. The Heat Watch Campaign summary report can be found at clbn.us/CountyHeatData. Chrissy Booker: 360-735-4613; chrissy.booker@columbian.com About the project: This story was made possible by Community Funded Journalism, a project from The Columbian and the Local Media Foundation that is funded by community member donations. The Columbian controls all content. For more information, visit columbian.com/cfj.

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