Earlier this month, 32 community science volunteers spent a day driving around Pierce County with heat and humidity sensors on their cars.

The goal: Map urban heat.

Urban heat islands are areas in cities that are often much warmer than nearby rural areas. Cities, roads and buildings gain heat during the day and radiate it into the surrounding air.

Cities can be 15-20 degrees warmer than areas with more trees and other vegetation!

A grant from the National Integrated Heat Health Information System (NIHHIS) funded the project. Tacoma-Pierce County Health Department coordinated the work with the support of 17 partners, including Pierce County Planning and Public Works and the Tacoma Tree Foundation.

Why map urban heat?

Extreme heat is the top weather-related cause of death in the U.S. With climate change, we are seeing heat waves increase in frequency, intensity, and duration.

People in cities don’t share the heat burden equally. Due in part to historical racism, the hottest neighborhoods are often home to poorer communities of color. Urban heat mapping campaigns identify them so communities can make them cooler for people disproportionately impacted by heat.

These community-science field campaigns are also a great chance to raise awareness.  One driver, Angela Gilmore, said the project meant a lot to her because, “You feel less powerless when you get involved.”

What will we do with the data?

Data collected by volunteers is on its way to a company called CAPA Strategies. It will create maps and other tools our partners can use to make decisions that will help reduce urban heat.

Urban planners can:

• Plant trees along streets to make shade, especially over dark surfaces.
• Add vegetation to urban spaces, including green roofs.
• Implement cool surfaces on roofs, roads, and walls.
• Provide more access to public cool spaces, including opening cooling centers during heat events.
• Vary the height of new buildings to increase airflow and create shade canyons.
• Use more natural ventilation in buildings.

A big thank you to all the volunteers and staff who made this work possible! Follow our social media accounts and sign up for the Your Reliable Source blog for regular updates on important public health topics.