Report of the Director-General of Public Health, New South Wales.

New South Wales. Department of Public Health.

Date:: [1937]

Catalogue details

Licence: Public Domain Mark

Credit: Report of the Director-General of Public Health, New South Wales. Source: Wellcome Collection.

114/154 (page 102)

It was considered, however, that when the bus was running, especially under load, the fumes might contain dangerous concentrations of carbon monoxide. On 24th August, 1937, experiments were carried out to determine the effect of the exhaust fumes when climbing the Spit Hill. A flexible extension hose was connected to the exhaust pipe of the bus and led to a cage in which guinea-pigs were placed. This method was similar to that used in the previous experiments (19-8-37), but in the earlier experiments, tho fumes were cooled by passing the hose through a water trough, whereas in these experiments this was found impracticable, and the temperature in the cage could only be reduced by by-passing some of the exhaust fumes. Experiment 1.—After idling for 75 seconds, the climb was commenced, and 45 seconds later the guinea-pig collapsed. It took 135 seconds to climb the hill; the guinea-pig was dead, probably due to heat of exhaust fumes. Its blood contained 10 per cent, of carbon monoxide. Experiment 2.—The conditions were similar to those in experiment 1, but some of the exhaust fumes were by-passed to reduce the temperature in the cage. After idling for a few seconds, the climb was commenced, and took 3| minutes. The guinea-pig was uncomfortable, and staggered about the cage. Its blood contained 20 per cent, of carbon monoxide. Experiment 3.—This experiment was similar to Experiment 2. Idling time, 30 seconds; climb, 3 minutes 45 seconds; the pig when taken out wras unconscious, but recovered. Its blood contained 25 per cent, of carbon monoxide. Experiment 4.—To determine the effect when running without the engine under load, a run lasting 15 minutes 45 seconds was made on practically level ground. One guinec-pig was removed after 4 minutes 15 seconds (the same time of exposure as in Experiment 3). The pig wras apparently not affected by the fumes, and no carbon monoxide was detected in its blood. The other pig was exposed for 15 minutes 45 seconds, was still active when removed, and its blood showed no signs of carbon monoxide. The results of both sets of experiments may be summarised as follows :— When idling or running on level ground, the amount of carbon monoxide produced is too small to be detected in the blood of guinea-pigs wdien exposed for from 2 minutes to 18 minutes. When running under load (that is up hill) the blood of guinea-pigs, which had been exposed to exhaust fumes for from 45 seconds to 3 minutes 45 seconds, contained from 10 per cent, to 25 per cent, of carbon monoxide. In view of the results obtained in the second series of experiments, it was decided to expose guinea-pigs for 8 hours in the driver’s compartment of two buses. This was carried out on 8th September, 1937. The first pig was carried on the Rose Bay North run, and the second pig on the Watson’s Bay run. Their blood w-as examined for carbon monoxide within a few minutes of removal from the bus, but none was detected. Conclusions.—These experiments indicate that carbon monoxide is only found in the exhaust fumes of Diesel buses when the engine is running under load, and this occurs, I am informed, when a bus is running up-hill or when a bus is getting under weigh after stopping. Apparently this depends on the fact that only on these occasions is enough oil injected into the compressing chamber to use up the available oxygen. This condition is the reverse of that found in petrol engines—here the generation of carbon monoxide is greatest wffien idling. The carbon monoxide generated by Diesel buses under the worst conditions is less than one-tenth of that generated by petrol-drawn vehicles under these conditions. Tho cabin of the Diesel bus, if it received the greater part of the fumes of an, exhaust, is only likely, in my opinion, to cause a hazard to health from carbon monoxide poisoning when running up-hill and repeated stopping and starting, and at no time will this hazard approximate that known to exist in petrol-driven buses. ANTHRAX. One death from anthrax occurred in the wool industry. The man was employed sorting sheep skins. According to the police report, he complained of headache six days before his death, and left work two days before bis death when he had a swelling under the left arm. His physician suspected anthrax, which was proved by post-mortem examination. The Agriculture Department was informed, and enforced the isolation and destruction of the skins coming from the district suspected of giving rise to this case. It was recommended that the Dead Wool Regulations be enforced in their entirety, and that fellmongering and working in sheep skins be brought under them. THE FELT HAT INDUSTRY. Following a complaint of a dust nuisance in a hat factory, three factories making felt hats were visited in order to compare the hygiene of the industry generally. Two of the factories were quite good from a hygienic point of view, but the third, the one from which the complaint arose, left much to be desired. In this factory, in the “ shearing ” process the exhaust attached to the machines was not sufficient to remove the dust and fluff, and much was in the air and lying around the floor and rafters. The general lighting and ventilation of the room was unsatisfactory. The “ cutting ' process was the worst in the factory. The room in which this wras carried out had no ventilation apart from the stairway leading to it. The windows were kept shut owing to the breeze blowing the fur about. The machines for the cutting process were fitted with exhaust ventilation, but so designed that a large percentage of the fluff, dust, and a little fur still found its way into the workroom. This fluff had settled on rafters, window sills, machines not in use, etc., and had accumulated on the floor in considerable quantities. Moreover, stacks of carroted skins were placed on the floor in one corner of this room, so the whole process was a potential mercury poisoning hazard. No signs nor symptoms of mercury poisoning were evident in the men engaged in the process. The general standard of hygiene and illumination of the rest of the factory were not considered satisfactory.