These results suggest that PSR augments physiological and psychological strain and reduces vigilance in the heat. Taking a nap seemed to be effective in reducing psychological strain and inhibiting the decrease in vigilance.

To examine how repeated cooling of fingers with a rest pause schedule at work affects cold-induced vasodilatation (CIVD), pain and cold sensation in fingers, six healthy men aged 21 to 23 years immersed their left index fingers six times in stirred water at 10°C for 10 minutes. After each cold-water immersion of the fingers, 5-minute rest pause was taken to observe the recovery process of the indicators. This cold-water immersion/rest pause test was carried out in a range of three ambient temperature conditions: 30°C (warm), 25°C (thermoneutral), and 20°C (cool) as experienced in daily life. At the ambient temperatures of 30°C and 25°C, marked CIVD response occurred and the CIVD reactivity did not significantly change upon repetition of cold-water immersion. The lowered finger skin temperature also tended to recover quickly to the pre-immersion level during each post-immersion rest period. At the ambient temperature of 20°C, however, the CIVD response weakened continuously upon repetition of immersion and almost disappeared during the final immersion. The recovery of finger skin temperature during each post-immersion rest was gradually delayed upon repetition of immersion. At every ambient temperature, finger pain and cold sensation induced by each cold-water immersion significantly decreased upon repetition of immersion and completely disappeared during each post-immersion rest period. Oral temperature during the experiment showed no significant change at the ambient temperatures of 25°C and 30°C, but it decreased significantly at the ambient temperature of 20°C. These results suggest that in a cool work environment where the body core temperature is liable to decrease, repeated finger cooling may weaken CIVD reactivity and delay the recovery of finger temperature during post-immersion rest periods. In such lower ambient temperature work conditions, subjective judgements such as the decrease in finger pain and cold sensation during repeated finger cooling and the absence of them during post-immersion rest may not be reliable indicators for monitoring the risk of progressive tissue cooling and frostbite formation.

The observation of winter lightning has been continued using magnetic links, digital recording systems for the current oscillograms, field mills, still cameras and video camera systems for the images of lightning channels on the west coast of Japan. Of the 59 magnetic link records, 59% were negative in polarity, 29% were positive, and the remaining 12% were unknown. The maximum peak current was over 270 kA in a positive flash, and the largest peak currents were found in positive flashes. The measured current oscillograms show that winter lightning stroke or ground flash often has a very long duration or continuing current. Moreover, two kinds of bipolar strokes were frequently recorded in the winter season. Nine of the 45 flashes showed bipolar strokes, 24 flashes were negative in polarity, seven were positive, and five were unknown.

In many parts of the world ongoing climate change during the last three decades has produced higher temperatures and occupational heat stress levels in both outdoor and indoor workplaces 1,2) . Working people are particularly exposed to these heating trends in tropical and sub-tropical countries, where excessive workplace heat exposures linked to the outdoor ambient thermal environment are a traditional part of local life, but heat waves in cooler countries are also affecting workers health and productivity 3) .Outdoor work is avoided by local people during the hottest part of the days in the hot season, as the heat stress from air temperature, humidity and wind, and the additional heat load from solar heat radiation, overwhelms the human physiological capacity to maintain thermal balance 4) . High workplace heat exposure is connected to various clinical effects and also to increased incidence of occupational injuries 5) .The notion that indoor workers are generally sufficiently protected via air conditioning, fans or other cooling systems does not apply to most industrial workplaces in low and middle income countries in hot parts of the world 6,7) . These are the countries where most of the global population lives. Rapid urbanization in Asia, Africa and Latin America adds to the local heat exposures via great amounts of construction work 8) and the Urban Heat Island effect 9) .The lack of technical protection against heat is an important threat to the health and productivity in workplaces. Future climate change will make this situation worse for millions, and maybe even billions, of working people 10) .Daily life non-work activities are also affected by high heat exposures, and for most poor people there is no distinction between work and daily chores. This special issue of Industrial Health presents papers on different aspects of occupational heat problems in relation to climate change. The papers present examples from different parts of the world, and highlight methods for heat exposure assessment 11) , standards for occupational heat exposures 12,13) , and the health and productivity risks of workplace heat in relation to climate conditions and climate change 14) . A small scientific conference on "Occu- Tord KJELLSTROM

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