Ways to promote a noise control programme.

The purpose of this study was to find out the proper ways to promote and to start a noise control programme in small and medium size industries. The situation of the noise control programme was inspected in four industrial enterprises. The noise exposure and the noise sources were studied and recommendations for noise reduction were given. The information concerning the noise control programme and noise levels was given to the personnel. How the noise control programme was started in the companies and which were the best ways to promote the programme were examined after 1 year. Noise reduction work was carried out in companies during the past year and new ideas were awaiting investment. The systematic noise control programme was not written on paper or connected to a risk management programme. The lack of proper models of a programme, lack of time and knowledge of easy means to reduce the noise were reasons for missing noise control programmes. The best ways to push up the noise control programme were to give information and examples of the programme. The EU-directive concerning machines and its noise information was a help in the noise reduction work connected with new investments.

Thermal effects of emollients on facial skin in the cold.

Ointments are traditionally used in Finland for protection against facial frostbite. Recent epidemiological reports showed unexpectedly, however, that the use of ointments is a statistically considerable risk factor for frostbite of the face and ears. The effects of 4 different emollients on facial temperature were studied in 46 acute cold exposures. The voluntary test persons sat in a cold chamber after emollients were applied thickly on half of the face, while the other half acted as an untreated control. Thermistors and an infrared scanner were used to measure skin temperature of symmetrical areas of the face. The thermal sensations on the corresponding sites were also recorded. Test emollients more often had an objectively cooling than a warming effect on facial skin. However, white petrolatum often produced a subjectively warming skin sensation. "Protective" ointments may cause a false sensation of safety, leading to increased risk of frostbite due to neglect of other protective measures.

Thermophysical effects of ointments in cold: an experimental study with a skin model.

The use of emollients on the face is a traditional way to protect the skin against cold injuries in cold climate countries like Finland, but their preventive effect against frostbite has been questioned. The purpose of this investigation was to define the thermal insulation and occlusivity of ointments in cold by using a skin model with a sweating hot plate. The properties of four different emollients were studied in both dry and humid conditions simulating transepidermal water loss, sweating, and a combination of sweating and drying. The thermal insulation of ointments applied on a dry surface was minimal. Evaporation of water from an oil-in-water cream caused significant cooling for 40 min after its application. The diffusion of water through the applied emollients changed their thermal effects depending on their composition and on the amount of water. Low input of water increased and high input diminished slightly the thermal resistance of ointments. The minimal or even negative thermal insulation of emollients in varying conditions gives them at best only a negligible and at worst a disadvantageous physical effect against cold.

Work ability of young adults.

This paper reviews the themes related to work ability of young adults. Premature working discapacity causes significant economical and social costs in Finland compared to other Nordic countries and has for that reason been studied most intensively there. Work ability is an interaction of social, environmental and individual factors such as physical fitness, coping skills, social support behaviour and health behaviour. Environmental factors influencing work ability can be concrete, like physical and chemical exposures or more abstract like unemployment. The work ability of ageing people has been studied intensively, while work ability of young adults has not been properly evaluated so far. The worsened economic situation in Finland has meant an excessive work load for those who still have work. At the same time the risk of permanent unemployment is increasing. This polarizationing affects especially the young because they may fail to enter the working life. Also factors related to childhood may affect and even determine work ability in adulthood.

Cutaneous heat loss in children during anaesthesia.

We have measured non-evaporative, cutaneous heat loss using heat flux transducers at eight skin sites in five children during anaesthesia and compared the data with basal metabolic heat production. The effect of disposable surgical covering and a radiant heater on heat flux was examined. The mean total heat flow rate before draping was 3-9 W higher than the basal metabolic rate after induction of anaesthesia with a simultaneous decrease in rectal temperature. Mean cutaneous heat loss was 62 (SD 9) W m-2 (9.5 (2.1) kJ kg-1 h-1) in children older than 1 yr and 84 W m-2 (17.2 kJ kg-1 h-1) in a 3-month-old infant. Disposable drapes diminished cutaneous heat loss by 29% and a radian heater by 77%. Heat conduction to the mattress was 21 (7) W m-2. These results showed that the decrease in core temperature after induction of anaesthesia was genuine cooling, that is heat loss exceeded heat production.

Prevention of the adverse health effects of cold by using infrared heaters.

The aim of the work has been to develop a planning guide for local infrared heating systems and to compare the results to the heaters in the work place. The planning process for radiators is started by defining the goal ambient temperature and then the electric power needed for the radiators. The planning result should always be compared to the recommendations for infrared radiation. The usefulness of the planning instructions were tested by building a local heater for a cooled storage where a computer was used. The increase in operative temperature and the physiological responses of workers were measured as well as the change in the thermal sensations after using heaters. With these heaters the operative temperature increases 7 degrees C. The skin temperature of the fingers increased about 7 degrees C, which is meaningful, when finger dexterity is needed in using computers. Also the thermal sensations increased all over the body. Both the planning instructions developed and the local heating system turned out to be very useful. Also the low costs of local heaters are a good reason for using them. However the exact direction and the narrow bean cone of the heaters are important in obtain the maximum benefit from them.

Vibration syndrome in railway track maintenance workers.

An inquiry was sent to all railway maintenance workers in three railway districts in Finland and hand-arm vibration was measured on the handlebars of tools used by maintenance workers. The study group included 252 (82%) subjects, whose mean age was 41 years and who had worked in track maintenance for 14 years (SD 9). In Finland there are over 600 railway maintenance workers who use vibrating tools. The frequency-weighted acceleration of hand-arm vibration was calculated according to the ISO 5349 standard. Hand-held tamping machines had caused most of the vibration exposure, and aw4h was 10.6 m/s2 measured on the handlebar of tamping machine, but many workers also used other vibrating tools. The annual vibration level was 2.5 m/s2 when the use of all vibrating tools and the exposure time was taken into account. In the questionnaire the prevalence of vibration-induced white finger (VWF) was 14% in the entire material, and the prevalence of VWF increased significantly with the total duration of the maintenance work. In addition, 39% of the subjects had suffered numbness of the hands, and the prevalence of hand numbness also increased significantly with the total duration of maintenance work. According to the measurements of vibration and the prevalence of hand symptoms the present investigation indicates vibration syndrome as being related to railway track maintenance work. In the exposure group, where tamping machines mainly were used and exposure to other vibration was small, the prevalence of VWF was also significantly higher, but the prevalence of hand numbness insignificant compared with the control group. In this study vascular and nerve hand symptoms were considered to cause serious trouble in work by 4-11% of the maintenance workers.

Hand-arm vibration and terrain vehicles.

Hand-arm vibration was measured on the handlebars of terrain vehicles (N = 36) and a postal inquiry was made among N = 2705 reindeer herders (snowmobile drivers). Since many subjects had also used other vibrating tools the snowmobile group proper (N = 334) was established. In the whole group 19% of the subjects reported having experienced white finger attacks and 48% numbness of the hands. The frequency-weighted acceleration of snowmobile vibration was 3.5 m/s2, and risk evaluation using the ISO 5349 standard predicted the prevalence of white finger well in the snowmobile group proper. The vibration levels were 1.6-7.9 m/s2 on snowmobiles, 5.5-11.8 m/s2 on all-terrain vehicles and 6.9-12.7 m/s2 on terrain motorcycles. The most critical points for damping the vibration were the motor mounting and resonance in the steering yoke. There is need for health care, technical improvements, and other protection means to reduce the symptoms of vibration in driving terrain vehicles.

Dose-response relationship between smoking and impairment of hearing acuity in workers exposed to noise.

The study included an inquiry and clinical examination of 443 reindeer herders (mean age 43 years) who frequently used noisy tools and vehicles, in particular snowmobiles and chain-saws. Age-adjusted hearing thresholds at 3 and 4 kHz deteriorated significantly with increased exposure to noise. There was the dose-response relationship between the amount of smoking and the impairment of hearing acuity when exposure time to noise was used as covariance. The amount of smoking was not significant until very heavy smoking (more than 144,000 cigarettes, i.e. 20 cigarettes/day for more than 20 years), and no smoking effect could be seen using the classification of current smoking habits. The results support the practice that screening of hearing acuity should be repeated more often in smokers than in non-smokers in noisy work so that hearing damage can be found in an incipient stage and noise-induced hearing loss effectively prevented.

Effect of occupational noise on the course and outcome of pregnancy.

OBJECTIVES: The goal of this investigation was to examine the effects of occupational noise during pregnancy prospectively. METHODS: The exposed group [continuous A-weighted sound level (LAeq(8 h)) > or = 78 dB] consisted of 111 pregnant women, and the reference group comprised 181 pregnant women with approximately similar work conditions but without noise exposure. The noise-exposed women had more frequently other inconveniences in their work, however, like shift work, impulse noise exposure, vibration, and a high or low temperature. RESULTS: With the limit of 78 dB (LAeq (8 h)), the course and outcome of pregnancy did not differ between the groups. When the noise exposure was 90 dB (LAeq (8 h)) or more, a decline in birthweight, either absolute [mean 3304 (SD 585) g for the exposed versus mean (SD 548) g for the unexposed, 95% CI of mean difference -471--+15 g] or related to the gestational age (below the 10th percentile [5 of 25 (20%) versus 13 of 180 (7%)]), was seen. These findings were more pronounced if the woman was simultaneously exposed to a standing work position or shift work. CONCLUSIONS: Working in high noise exposure can be considered a form of risk during pregnancy.

Calculation of mean skin temperature and changes in body heat content during paediatric anaesthesia.

Mean skin temperature and changes in body heat content were calculated in several different ways from measurements made in five children during operation. Mean skin temperatures were calculated from 162 sets of measurements using 15, 12, eight, seven and four skin sites with various formulae modified according to age. The results of other formulae were compared with age-adjusted, area-weighted 15-site mean skin temperature which was used as a reference. Changes in body heat content were calculated from Burton's equation in different ways and errors from different variables in the formula were evaluated. Mean skin temperature from 12 skin sites was within 0.5 degrees C of the 15-point reference method, and that from four sites within 1 degree C. The core temperature selected and the weighting coefficients used in calculating mean body temperature were more important sources of error in the determination of change in body heat content than was mean skin temperature.

Hand-arm vibration in snowmobile drivers.

Hand-arm vibration was measured on the handlebars of snowmobiles (N = 29) and a postal inquiry was made among reindeer herders, N = 2,705. Since many subjects had used also other vibrating tools a snowmobile group proper (N = 334) was established, and in this group 18% of the subjects reported that they had experienced white finger attacks and 48% numbness of the hands. The age-adjusted prevalence of the white finger syndrome was more than three times higher in the snowmobile group than in the controls. The frequency-weighted acceleration of snowmobile vibration was 3.5 m/s2, and risk evaluation based on the annex of the ISO 5349 standard predicted the prevalence of the white finger syndrome well in the snowmobile group. The most critical points for damping the vibration were the motor mounting and resonance in the steering yoke. There is a need for health care, technical improvements, changes in working habits and other protection means to reduce the symptoms of vibration associated with driving terrain vehicles.

Thermal responses in the body during snowmobile driving.

Thermal responses were examined in 12 healthy men during snowmobile driving (tests for 1 1/2-2 1/2 hours) in mild winter conditions. Ambient temperature ranged from -1 to -13 degrees C and average wind chill index from 1,050 to 1,520 kcal*m2/h. The subjects (23-49 years old) wore their ordinary winter clothing (insulation 1.7 - 2.4 clo). Work rate during the driving was 280-350 W. Rectal temperature increased slightly during driving, and mean skin temperature decreased quickly and fluctuated afterwards at a level 2-3 degrees C lower. Mean body temperature decreased by 1.2 degrees C in the most extreme case. Local cooling on the face and on the peripheral area of the extremities was considered the most serious problem: those temperatures were often below the limit of performance degradation and indicated occasionally the risk of frostbite. The winter conditions were mild in the present study, and on colder days cooling problems will be more severe, as the high incidence of frost injuries reported earlier indicates.

Noise and hearing loss in reindeer herders.

Air conduction hearing thresholds were examined in 512 reindeer herders (aged 18-65 years, clinically normal ears) to evaluate the prevalence of noise-induced hearing loss. The hearing thresholds at 6 kHz showed significant noise-type impairment of hearing compared with those in the ISO 7029 standard or a Finnish reference population. The subjects were exposed to noise mainly in the use of snowmobiles and chain saws: daily noise exposure ranged from 93 to 104 dB(A). The age adjusted hearing thresholds deteriorated with the total noise exposure time, especially at 3 and 4 kHz. The prevalence of significant (class IV) hearing loss was 15% and impairment of hearing was frequently found even in the younger age groups. Although the use of ear protectors seems to be increased among reindeer herders, it still appears to be insufficient, and efforts to promote their use are needed.

Combined effects of cold, vibration and smoking, particularly in snowmobile users.

In a living and working environment more than one factor is usually important for physiological and psychological responses in the body. In this report the effects and combined effects of hand-arm vibration and cold, in particular their effect on frostbite, has been reviewed. As a second example is given the combined effect of vibration and smoking on vibration-induced white finger. In both cases our previous work among reindeer herders frequently using snowmobiles has been utilised as an example. Descriptive terms for combined effects have varied in previous multi-exposure studies. Here, the terminology recommended in the Saariselkä agreement has been applied, and according to that the combined effect between cold and vibration on frostbite was called synergism and between vibration and smoking on white finger Bliss synergism.

Whole body vibration and the snowmobile.

The whole body vibration from the seat and foot board was measured during ten years from 11 different snowmobiles to evaluate the exposure and the need for technical improvements. In a questionnaire more than half of the drivers had back pains but only a few of them considered the whole body vibration as a health hazard. However in the literature there is often comments on spinal injuries related to shock vibration. The frequency-weighted acceleration of snowmobile vibration was from 1 to 6.1 m/s2 and the risk evaluation using the ISO standard predicted the problems. Speed and the unevenness of the driving terrain caused vibration. The damping depends on the properties of the seat, terrain and speed limits. Also the driving posture is important. Especially on the snowmobile tracks the whole body vibration was high and according to modern knowledge more attention should be paid the technical properties of snowmobiles.

Snowmobile driving and symptoms of the locomotive organs.

The role of snowmobile driving as a factor in symptoms of the locomotive organs was examined in 1,793 reindeer herding men using a postal questionnaire. Thirty-eight % of the respondents reported troubles in the upper limbs and shoulders which according to their own judgement were caused by snowmobile driving, and 34% reported such symptoms in the knees and 42% in the back. Aching, pain or tenderness upon movement in at least one joint during the current year, inquired by independent questions, were reported by 46% of the men. The prevalence of joint symptoms felt in the elbow (reported by 15% of the subjects), wrist (13%), fingers (10%), shoulder (22%) and knees (20%) increased by a factor of 1.6-2.5 from those driving a snowmobile 1-20 days a year to those driving 150 days or more. The findings confirm earlier reports of increased occurrence of symptoms in the locomotive organs in snowmobile drivers and justify technical and other preventive measures.

Service of snowmobiles in the wilderness and villages.

The maintenance of terrain vehicles like snowmobiles has been developed for arctic wilderness use by paying attention to occupational health, safety and quality and efficiency of work. A small tent carried on a snowmobile sledge supplied with heating and lighting equipment was planned, built and tested. It was sized based on an ergonomic survey for the servicing of snowmobiles. The planned thermal and occupational aims were reached at temperatures down to -35 degrees C. Two movable, shielded fluorescent lamps with total of 140 W electric power was enough to produce 150 lx illumination and the local illumination for the repair point was 700 lx. The 8 kW warm air fan had enough power to hold the temperature inside at the desired level with an outside temperature of -35 degrees C. The fan was also used as a local heater by conducting warm air to the hands and tools. The temperature of the fingers was close to the comfort level, when repair work was carried in the tent. When the repair work was carried out outside, the finger temperature was near the risk of cold injury. The handles of the tools were made from heat insulating materials, which raised the contact skin temperature with about 3 degrees C.

Developing the snowmobile helmet.

With the annually increasing use of snowmobiles in the Nordic countries the amount of accidents is also increasing. The head is the location of some of the most serious injuries with head injuries comprising 12% of all injuries. At the time being there is no special standard for the snowmobile helmet and there are mainly two kinds of helmet models on the market: full face and open face helmets. The most significant differences between the helmets were observed in the subjective evaluation, whereas the differences were minimal in technical evaluation. According to this study an open face helmet was more comfortable than a full face helmet. The present helmets have many deficiencies such as the lack of thermal comfort, high weight, slow removal of mist from the visor and unsatisfactory hearing protection. The aim of future development projects should be to make a more comfortable and lighter helmet. One important aspect of the project could be to integrate hearing protectors and an information channel in the helmet.

Assessment of cold stress in outdoor work.

The evaluation of cold stress in working life was done in 13, mainly outdoor, occupations and 143 workers using local temperatures, body cooling and thermal sensations. The subjects in the study were young, healthy men and they wore the type of winter clothing generally used in those ambient temperatures (+6...-29 degrees C), for in a work load of from 112 to 480 W. Local temperatures on finger skin indicated that manual dexterity was often reduced in outdoor work. A risk of frostbite was frequently found on the cheek and the wind chill index predicted the risk quite well. Body cooling was often temporarily too high when measured by heat debt and mean skin temperature. Thermal sensations were cool or cold occasionally in 28% of the workers interviewed. The insulation of clothing worn was often lower than the IREQmin-value recommends. The results showed that in outdoor work in winter time cold stress frequently reduced (70%) working ability at least for a short period. Mean skin temperature seems to be, in practice, a useful indicator for body cooling and the IREQmin-value was suitable, especially in light work, to indicate body cooling. A very sensitive factor for the expression of cold stress was finger temperature, at least as an indicator of finger dexterity. Due to the adverse health effects found the cold stress should also be evaluated more systematically in occupational health and safety with health examinations, with protective clothing and technical preventive means.