Footwear for cold work: a field study at a harbour

A series of field studies at cold workplaces were initiated. This paper deals with a study at a harbour and the main attention is paid to the thermal responses of the feet and footwear performance. The study was carried out in February. Eight male workers were the subjects. They were selected among volunteers who carried out four different jobs in pairs. The warm winter boots were provided by the experimenters. The insulation of a boot (size 41) was measured on a thermal foot model and was 0.34 m2°C/W. One subject used his own shoes with an estimated insulation of about 0.23 m2°C/W. The subjects used one pair of thin socks (about 75 g/pair). Temperature sensors were taped to the second toe and dorsal foot. The workers were observed during the whole workday. The foot skin temperatures stayed relatively high, usually over 30 °C, except in the subject with shoes whose foot skin temperature was mostly below 30 °C. The lowest toe temperatures were occasionally around 17-18 °C, but commonly they were higher than 25 °C. The sweat accumulation in the footwear was at average 20 g per day and foot (1.3-3.8 g/h). Around 2 g of that stayed in the socks at the end of the day. The footwear was generally considered comfortable. Still, problems with the footwear were: difficulty to walk, limited mobility and poor fit, limiting effect on work ability, cold feet (the subject with shoes) and sweaty feet. The provided boots had too high insulation for the particular weather conditions (4 to 8 °C). The shoe insulation seemed not to be enough (one subject). Under the studied climatic and work conditions the recommended insulation would be between 0.25 and 0.30 m2°C/W. (Less)