Mastarbete i kyla

Désirée Gavhed, Kalev Kuklane, Ingvar Holmér. Work on masts in cold conditions. Arbetslivsrapport 1999:22.
Eight tower operators were studied in February during their ordinary duties in masts in four regions of Sweden. The activities of the workers were observed during a full working day and the skin temperature at seven spots, body temperature and heart rate were measured continuously. They also rated their thermal sensation and perceived exertion at several occasions. The air temperature varied between -13 and 3 °C and the wind speed between 1 and 13 m/s. The tasks were maintenance, mounting and exchange of equipment on the masts. The workload varied much during the day from very light (standing) to very heavy (climbing with loads). The oxygen consumption, measured during climbing, was 15 - 38 ml/kg·min. The majority (six out of eight) of mast workers were bothered by cold, five also by wind. Four had lower insulation than recommended according to the cold stress index IREQ. Six workers reported that they sweated during some part of the day. The face, the hands and the feet were reported as being the coldest body parts. This was probably mainly due to bad insulation in gloves and shoes, contact with cold surfaces, wind and periodically low physical activity. The finger temperature decreased to 6-14 °C. The lowest foot and toe temperature measured was 21 °C and 10 °C, respectively. All workers had lower toe temperatures than 18 °C at some occasion. Two workers were unsatisfied with the safety shoes. They were considered cold and uncomfortable. The weight gain in the socks and shoes was 6-94 g, which corresponded to an evaporation rate of above 2-13 g/h. The other work clothes used were considered to protect enough from cold. An improved flexibility of the coverall is recommended to let out excess heat. To reduce the risk of evaporative cooling of the feet, it is recommended that the footwear are detached at each break indoors. Electrical shoe heaters may be of good value to get rid of the accumulated moisture in the footwear. The shoe material should be flexible also in the cold. The sole material should not be stiff in the cold and give good friction against the mast construction snow and ice. There is a need for ergonomic improvement of the work gloves, concerning fit, design, insulation, protection against injuries and flexibility. Facilities for heating should be arranged. All mast huts should be heated. Hot air fans or radiators may be used for effective heating of cold body parts. In other conditions, heat bags can be used for cold prevention or heating. Finally, the study showed a need for good oxygen uptake capacity and good health at mast work. Moreover, good muscle power is required at lifting and lowering of equipment and tools.
Key words: cold, temperature, heart rate, oxygen consumption, wind, thermal sensation, workload, clothing, gloves, shoes