Quantitative verification of the effects of using parasols

Climate change impacts

Climate change has increased summer thermal stress and the risk of heat stroke. The adoption of adaptive measures for heat mitigation is required.

Adaptation activity

In order to quantitatively assess the effectiveness of normal and UV-shielding parasols as heat countermeasures (see Note 1), a study run by the Ministry of the Environment examined human physiological and psychological responses. Trials were carried out in a weather chamber equipped with an artificial heat source to stand in for the sun. Physiological reactions (heart rate, weight loss, skin and ear temperature) and subjective impressions (perceived heat, discomfort, humidity, perspiration, air flow, effectiveness in blocking heat, perception of irradiance, impact on physical movement and general satisfaction) were measured with subjects wearing hats, using a normal parasol, and parasols with added UV-protection (Fig. 1).

Results showed that UV-shielded parasols were the most effective amongst the three, for both physiological response, and subjective impression, followed by normal parasols. For example, there was a statistically significant decrease in weight loss (including perspiration and involuntary evaporation (see Note 2)) with normal and UV-shielded parasols compared to only wearing a hat. The decrease in body weight was 17.3% less with a UV-shielded parasol compared to hats, and 12.1% less between UV-shielded and normal parasols.

In addition, public health information (Fig. 2), using quantitative data from these trials, was displayed where parasols are sold in department stores and major retailers with feedback being sought from shoppers. An example of a feedback comment is "the use of thermography and the information that perspiration is reduced by 17% clearly communicate the benefits of parasols".

Outputs / Expected benefits

Quantitative verification data has made it possible to promote the use of UV-shielding parasols as a more effective heat countermeasure. It is also expected that greater public awareness will be achieved with the creation of promotional material based on the verification data.

(Note 1) A UV-shielded parasol is a sunshine parasol that cuts 99% or more of solar radiation.
(Note 2) Involuntary evaporation refers to water loss, other than perspiration, from the skin or through exhalation.