2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
HEAT STRESS AND EXPOSURE TO UV RADIATION
IN ROOF WORK
Raija Ilmarinen 1 , Henna Hämäläinen 1 , Harri Lindholm 1 , Maila Hietanen 2 ,
Patrick von Nandelstadh 2
1 Health and Work Ability, 2 Work Environment Development,
Finnish Institute of Occupational Health, Helsinki, Finland
Contact person: raija.ilmarinen@ttl.fi
INTRODUCTION
Heat stress combined with solar ultraviolet (UV) radiation is an occupational health issue in
outdoor work during summer months. As a result of high heat stress levels, mental confusion
related to heat illnesses may predispose workers to unsafe activities and the risk of accidents
increases. Adverse effects of exposure to UV radiation focus on eyes and skin. Short term
exposure can result in photokeratitis of the eyes and erythema ("burning") of the skin. Long
term exposure can cause cataracts of the lens, premature skin ageing, and different types of
skin cancer.
This field study was conducted to elucidate the physiological effects of heat stress, and to
determine the daily UV dose during sunny summer months among roof workers. The results
are used to develop guidelines for Finnish outdoor workers for the prevention of harmful
thermal health effects, and to evaluate the need for protective clothing against UV radiation.
METHODS
Subjects. Nine voluntary and healthy professional roof workers with an average age of 35
(25−49) y, height of 176 (171−185) cm, weight of 79 (58−108) kg, BMI of 25 (20−36) kg/m 2 ,
body fat percentage of 19 (9−33)%, and body area of 1.9 (1.7−2.2) m 2 participated the study.
Before the experiments, the subjects underwent a medical check-up including a clinical
cardiopulmonary exercise test and a heat stress test. The subjects had no history of heatrelated
diseases and their average evaluated V& O2max
was 40.0 (33.3−49.2) ml/kg·min -1 .
The research protocol was reviewed and approved in advance by the Institutional Research
Committee and the Coordinating Ethics Committee of the Hospital District of Helsinki and
Uusimaa (Finland). The subjects gave written informed consent before the experiments and
received no payment for their participation.
Measurements at work sites. The physiological field measurements were conducted during
normal working days at several roof paving sites in southern Finland in June 2006. The
registrations of UV radiation were carried out in June and July 2005 and 2006. The subjects
were clad in protective clothing they received from employers. After instrumentation the
measurements started at about 7 am and continued until about 15 pm.
Daily local weather was received from the weather stations of Finnish Meteorological
Institute near working sites. Air (Ta) and globe temperatures (Tg) at working sites were
measured continuously (Veritec Instrument Type 1400), and relative humidity (RH) and air
velocity (Va) were recorded every two hours (Vaisala Humicap HMI 31 and ALNOR F70).
WBGT-index was calculated for hot working days.
Workers' exposure to solar ultraviolet radiation was measured and the daily UV dose was
determined by using personal electronic data loggers (Gigahertz-Optik Model X2000-4). Each
dose meter contains two detectors: one for measuring the UV-A radiation (320−400 nm)
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