Characterizing the Energy Budgets of Children during Active Play in Hot Weather through the use of Personal Sensing Devices

Overexposure to ambient variables, such as ultraviolet radiation (UVR) and extreme heat, are considerable risk factors to children’s health. Inconsistencies exist in risk assessments due to lack of fine-scale exposure data connected to the built environment, thus true exposures to extreme heat and UVR are often unknown. This research addresses child exposures to extreme heat and UVR in outdoor playground microenvironments in a poverty and educationally stricken neighborhood in Lubbock, TX. The objectives of this field study are to 1) determine children’s individually experienced temperatures (IET) and UVB exposure lined to physical activity (PA), 2) compare modeled and actual thermal sensation (ATS) values indicative of thermal comfort (TC), and 3) assess how playground design affects overall exposures and PA levels.

Sixteen children participated in a three-week field study during 60min of after school activity in the spring of 2016 in Lubbock, TX. UVB dosimeters and thermochron iButtons were used to collect IET and UVB data. Stationary microclimate data of air temperature, humidity, wind, and UVB radiation were also collected. All students wore Polar Team Pro monitors for heart rate monitoring and accelerometry. All data were incorporated into the COMFA energy budget model to calculate the predicted thermal sensations (PTS), which were directly compared to ATS and preferred change surveys provided by the children. Comparisons of IET, UVB radiation, PA, and TC were completed over various surfaces, and in shade/no shade conditions.

Field results demonstrate high variability of surface temperatures and IETs experienced by children over various play surfaces. Energy budget distributions were skewed to the ‘hot’ end of the scale, with children having a narrower range of neutrality based on ATS votes. Children often expressed ‘comfort’ although preferring to be ‘much colder’, a finding which may be related to children’s limited experience dealing with symptoms of heat stress. Finally, UVB exposures were significantly less while under a shade sail, with personal UVB exposures differing significantly from the onsite microclimate station UVB monitor.  

Heat stress connected to solar exposures lowers PA and TC in children, a vulnerable subpopulation to extreme heat and radiation. However, proper playground design can help mitigate heat stress both now and as our climate changes. Multiple microclimatic and human activity factors result in differing values by person and as compared to stationary in situ data, where understanding offsets of temperature or UVB may provide improved modeling capabilities for health end points. Environmental sensing technologies offer new opportunities to understand such exposures and monitor children’s exposures while allowing for safe and active play.