Extreme Heat at Outdoor COVID-19 Sites

FLIR thermal image at the UArizona POD. Thermal image showing temperature differentials with the colder evaporative coolers on the left (purple) and the hotter vehicles on the right (yellow).

Final paper of my Extreme Heat at Outdoor COVID-19 Vaccination Sites research with Nicole Iroz-Elardo, Erika Austhof, Ida Sami, and Mona Arora is now available! The project began by invitation from the site operators who were very responsive in using the recommendations. It was an honor to work on this project with my colleagues to help increase the safety of the dedicated volunteers and workers involved in the early vaccination efforts.


Extreme heat is an increasing climate risk due to climate change and the urban heat island (UHI) effect and can jeopardize points of dispensing (PODs) for COVID-19 vaccination distribution and broader public health emergency preparedness (PHEP) response operations. These PODs were often located on large parking lot sites with high heat severity and did not take heat mitigation or management strategies into account for unacclimated workers and volunteers. To investigate the personal heat exposure of workers, volunteers, and clients at three PODs in Tucson, Arizona, we collected ambient air temperatures, wet bulb globe temperatures (WBGT), surface temperatures, and thermal images. We also made qualitative observations and compared data against daily meteorological records. Ambient air temperatures at all three PODs exceeded the meteorological recorded high. WBGT on average were 8°F (4.4 °C) higher in full sun locations than shaded locations such as tents. Evaporative cooling decreased ambient air temperatures by 2°F (1.2 °C) when placed one per tent, but decreased ambient air temperatures by 7°F (3.9 °C) when placed en masse in a larger tent. Vehicle surface temperatures exceeded recommended safe limits of 140°F (60 °C) at all three sites, with a maximum temperature recorded at 170.9°F (77.2 °C). Public health professionals should consider heat resilience, including heat mitigation and management measures, in POD and PHEP response operations to reduce exposure. This includes considering the UHI effect in the siting of PODs, applying heat mitigation strategies in the design of PODs such as the adaptive use of solar panels for shading, and improving heat safety guidance for workers and volunteers.

Full open-access paper is online at: https://www.sciencedirect.com/science/article/pii/S2667278221000407