[The temporal variation of fine dust concentration in the air in fattening pig housing. Hygienic and occupational medicine aspects]. / Die zeitliche Variation der Feinstaubbelastung der Luft im Mastschweinestall. Tierhygienische und arbeitsmedizinische Aspekte.

The temporal variation of airborne dust concentration (less than or equal to microns) was examined with an instrument operating on the nephelometer principle combined with a specifically adapted data processor in two pig fattening houses at night, at day and during feeding. Activities and factors affecting the dust level were noted. The measurement system allows the uptake and storage of values in the stable. For further processing, the data can be transmitted to a personal computer. In our experience the instrument is very suitable for the registration of airborne dust concentration in animal confinement buildings. Peak concentrations ranging up to 100 mg/m3 in intervals of 10 seconds could be measured. The data of a longer trial were averaged over 1.5 minutes. Animal activity has a great influence on the dust concentration. The highest mean concentration of dust with maximally 2.5 mg/m3 were determined at feeding time and when pigs were disturbed. The concentration of airborne dust particles was obviously lower at night than at day. A defect of the ventilation system, referable to the emission of feed dust, was disclosed by the continuous registration of air dust concentration, in one of the pig fattening houses. During the feeding periods, for a short time of less than 20 seconds, the dust concentration rises to 100 mg/m3 resp. 27 mg/m3 by dry resp. wet feeding. About 30 minutes after feeding the dust concentration was again in the average of 0.67 mg/m3. In conclusion the results were considered under hygienic and medical aspects.

Changes in lung function after working with the shotcrete lining method under compressed air conditions.

Shotcrete techniques under compressed air are increasingly applied in the construction of tunnels. Up to now little is known about the influence of shotcrete dusts on the function of the lung. The lung function of 30 miners working with shotcrete under compressed air (before and after one shift) was measured. They carried personal air samplers to assess the total dust exposure. Long term effects were studied on a second group of 29 individuals exposed to shotcrete dusts and compressed air for two years. A significant increase of airway resistance and a significant decrease of some flow-volume parameters were found after one workshift. These changes partially correlate close to the dust exposure. After two years exposure a significant decrease of mean expiratory flow (MEF)50 and MEF25 was found. These results point to damage in the small airways and emphasise the major role of the lung function test--including the flow-volume manoeuvre for the medical examination of the workers. Additionally, they should carry filter masks.

[Noise-induced hearing loss caused by dental turbines]. / Lärmschwerhörigkeit durch Dentalturbinen.

Sound level measurements and third octave analyses were carried out to estimate the risk of hearing impairment caused by working the turbine drills. Idling noise of two turbines equipped with ball-bearings and air-bearings respectively and the effects of different burs under varying load conditions in particular were examined. Finally, the background sound level in a great consulting room of a dental clinic at medium activity was looked at. Without any exception the sound levels were situated below 85 dB (A). The sound level exceeded 80 dB in only a few third octave bands; this was the case only with the antiquated ball-bearing turbine. Working with turbine drills requires only a fraction of the total treatment duration, resulting in a very low equivalent sound level. As a consequence a hearing impairment risk may be excluded within the reach of this investigation.