Heat and UV exposure regularly affect pedestrians utilizing active transport in Maricopa County, Arizona. Ultraviolet radiation affects the epidermis (skin) and is related to skin cancer. Gathering UV data provides information that is not currently available to optimize shade coverage of active transport zones. The study collected fine-scale micrometeorological data in high-active transport areas in Tempe and Phoenix to quantify heat and UV stressors along the pedestrian route (~20-minute segments). We utilized a mobile weather station (MaRTy) pulled along the walking routes to simultaneously collect air temperature, humidity, wind speed, latitude, longitude, and solar and infrared radiation. In addition, attached six ultraviolet dosimeters in a 3D setup, similar to the net radiometers. 20-minute transects were segmented into three portions throughout the day (morning, midday, afternoon) to simulate a workday commute. The transect was a low-income community, with three bus stops. Data calculations include: 1) Average Mean Radiant Temperature (MRT) and surface temperature along transects. 2) A Standard Erythemal Dose (SED) was collected from UV dosimeters. 3) Bus stop ridership frequency is being used to calculate “degree minutes” of exposure along selected transect.
Results/Conclusions
Urban planners can determine how shade structures can be utilized along a route and at a bus stop to protect pedestrians from heat stress and overexposure to sunlight during peak foot traffic of the day. Further, bus stop and street shading have potential to employ green infrastructure involving ecological processes (e.g., plants, vegetative artwork, bus stops, green roofs to attract pollinators; other autotrophs to provide habitats, nutrients, and energy for organisms). Green infrastructure will benefit the urban heat island by providing cooling. The MRT at the 20 minute transect at 4-5 pm, overall had a mean of 60°C, surface temperature over all had a mean of 50.31°C. Bus Stop 1) had an MRT max of 46.52°C, min: 42.63 2) Max: 51.45, min: 49.64 3) Max: 65.48, min: 65.03. The variation in MRT shows that there was little to no benefit to the shade structures present. The time of 3 pm to 5 pm had the highest ridership frequency throughout the day for the three bus stops. The SED results at 12:10-1:25 pm breached the erythema threshold, thus posing a high risk for skin reddening/burning during this time. Further results and analysis will be included at the talk.