Mitigation of pedestrian heat stress using parasols in a humid subtropical region
- 172 Downloads
Concerns over heat illness have been an increasing social problem in humid subtropical regions. One measure for avoiding excessive heat stress in hot outdoor environments is the use of parasols or umbrellas. The advantage of parasols is that they are a mobile and inexpensive way to provide personal shade outdoors. The objectives of this study were to compare the wet-bulb globe temperature (WBGT) under parasols and at an unshaded point as a reference, and to quantify the reduction in WBGT from the use of parasols in a humid subtropical region. Measurements using three parasols of different colors and materials were conducted at the athletics field at Daido University, Nagoya, Japan, between 9:00 and 15:00 Japan Standard Time in August 2015. The WBGT was obtained at heights of 0.1 m (ankles), 1.1 m (abdomen), and 1.7 m (head) above ground, according to the measurement procedure described in ISO 7243. On a sunny and partly cloudy day, the use of a parasol lowered the average globe temperature by up to 6.2 °C, through blocking direct solar radiation. The average reduction in WBGT by the parasol was found to be 1.8 °C at head level in sunny conditions with solar radiation of over 800 W/m2. The reduction in WBGT at head level by the use of parasols in sunny conditions was greater than that in cloudy conditions. However, although parasols can reduce WBGT at the head level of the user regardless of solar radiation, they cannot reduce it at the level of the abdomen or ankles.
KeywordsParasol Umbrella WBGT Heat stress Thermal comfort
This work was supported by JSPS KAKENHI Grant Number 25350085. The authors would like to thank Ms. Mana Kawashima and Ms. Kana Inuzuka for conducting a series of measurements and observations.
- Asayama M (2009) Guideline for the prevention of heat disorder in Japan. Glob Environ Res 13(1):19–25Google Scholar
- Égerházi LA, Kovács A, Unger J (2013) Application of microclimate modelling and onsite survey in planning practice related to an urban micro-environment. Advances in Meteorology 2013 Article ID 251586. doi: 10.1155/2013/251586
- Fire and Disaster Management Agency (2015) Ambulance report of heat disorders in 2015 (in Japanese). http://www.fdma.go.jp/neuter/topics/houdou/h27/10/271016_houdou_1.pdf. Accessed 22 Nov 2016
- ISO 7243 (1989) Hot environments—estimation of the heat stress on working man, based on the WBGT-index (wet bulb globe temperature)Google Scholar
- Jojima E, Sueki T, Baba N (2007) UV ray and thermal ray protection properties of parasols. Bulletin of Human Life Sciences, Jissen Women’s University 44:126–131 (in Japanese)Google Scholar
- Kuno T, Hori Y, Kobashi M, Watanabe S, Ishii J (2013) Measurement of short- and long-wave radiation flux under various parasols. Proceedings of the 37th Symposium on Human-Environment Systems pp. 53–56 (in Japanese)Google Scholar
- Ministry of the Environment (2014) Heat disorders health guidance manual (in Japanese). http://www.wbgt.env.go.jp/pdf/envman/full.pdf. Accessed 22 Nov 2016
- Pickup J, de Dear R (2000) An Outdoor Thermal Comfort Index (OUT-SET*)—part I—the model and its assumptions, biometeorology and urban climatology at the turn of the millennium, 279–283. WCASP 50: WMO/TD No. 1026.Google Scholar
- Sugiura M, Oda K, Watanabe S, Ishii J (2014) Evaluation of outdoor thermal environment with parasols by the subjects. Proceedings of the 38th Symposium on Human-Environment Systems, pp. 111–114 (in Japanese)Google Scholar
- Yaglou P, Minard D (1957) Control of heat casualties at military training centers. AMA Arch Ind Health 16:302–316Google Scholar