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Technology Frontier

Feb 2014 Issue

Cooling vests effective in beating the heat, Lower health risks in blazing temperatures

A scientific study that raises safety standard for outdoor workers

Hong Kong is getting warmer and warmer.  Sweltering summer heat is a big concern of outdoor workers who perform physically demanding duties.  At the moment, outdoor workers are given access to shade, water and even rest breaks, as best measures against heat stress.  However, numerous evidences surfaced and suggested that extreme heat poses real health risks, according to Professor Albert Chan, Interim Dean of the Faculty of Construction and Environment.  Common problems include dehydration, heatstroke, and elevated heart rate.  The government is now searching for appropriate ways to offer better protection. 

When the temperature becomes too high for the body to cope, the body loses its ability to cool down and becomes overheated, and that’s where heatstroke sets in.  Strenuous activity further increases the risk.  Can outdoor workers be better protected on the job?
Experts at The Hong Kong Polytechnic University have carried out a one-year study to help workers remain cool.  Cooling vests were given to workers who spend a lot of time in scorching heat, while researchers led by Professor Chan set out to determine their effectiveness.
The study was commissioned by the Occupational Safety and Health Council (OSHC) in an effort to prevent heat stroke.  Cooling vests were put to the test out in the field.  Scientific studies were conducted in twelve locations, which included construction sites, the airport apron, outdoor gardens and public canteens.  Two models of cooling vests imported from the U.S. and Korea designed for soldiers and athletes were given to 130 workers.  The participants wore one type of cooling vest in the morning and switched to another type in the afternoon.  Vital signs such as body temperature, blood pressure and heart rate were taken before and after each session.  
After these on-site studies, the team identified the model which offered more comfort and efficiency for further testing.  These tests were also carried out in a climate-controlled environment, where participants performed strenuous tasks and had their body conditions closely monitored.
The study found that wearing a cooling vest did provide the much-needed cooling relief.  Vests with cooling fans have been shown to reduce body temperatures and allow the wearers to recover faster and get back in shape sooner.
“This new information should help improve decisions regarding safety measures against intense heat,” said Professor Chan.  “The study provided a sound basis for employers to consider about the cooling vest solution before making any investment.”  
The Labour Department, in collaboration with OSHC, launched a pilot scheme in summer 2013 to promote cooling vests.  Under the scheme, 1,500 cooling vests were distributed to 248 participating organisations from 4 industries for further testing.  It marked an important step in the right direction to protect workers from health-threatening temperatures.
Apart from workers’ health and safety, intense heat also affects their productivity.  “Working in a hot environment is very uncomfortable, and will amplify stress and fatigue at work.  It can also influence their performance and judgement, while increasing the likelihood of errors and accidents at work,” continued Professor Chan.  He therefore emphasised the importance of health and safety management for workers under extreme heat.  
The findings are also valuable to Professor Chan and his team as they move on to develop cooling vests for construction workers which will keep the wearer comfortable in summer weather.