Occupational Hygiene Conditions in MTS Workshops

Sanitary Physician B. A. Ryvkin

From the Pskov District Sanitary and Epidemiological Station

We examined the workshops at 12 machine and tractor stations (MTS) in Pskov Oblast. Of these, 10 workshops were of nonstandard design and 2 had been built to the obsolete standard design No. 1658.

Housing a number of shops with diverse technical processes in a single machine and tractor workshop building brings several harmful factors into close conjunction: chemical air contaminants, unfavorable meteorological conditions, noise, and poor lighting. The coppersmithing, forging and welding, and engine sections, as well as fuel-system equipment repair, warrant particular attention.

Tinning, soldering, and the melting of babbitt metal for casting bearings are carried out in the coppersmithing shop. The survey showed that MTS workshops use almost exclusively BN and BN-16 grades of babbitt, which contain up to 70% lead. When bearings are cast, the babbitt is heated to its melting point, and lead vapors enter the workshop air. Air samples taken near the bearing-casting workstation showed lead concentrations of 0.000014–0.000018 mg/L. Still higher concentrations cannot be ruled out, because the brief duration of the bearing-casting operation made it impossible to draw more than 250 L of air through the sampling apparatus.

In addition to lead vapors, the air in the coppersmithing shop contains substantial amounts of carbon monoxide—approximately 0.0621–0.0756 mg/L. In one of the machine and tractor workshops surveyed, coppersmithing was carried out in the forge, where the carbon monoxide concentration reached 0.3164 mg/L when the hearths were being lit.

These chemical contaminants make it necessary to install exhaust ventilation in machine and tractor workshop coppersmithing shops, with exhaust hoods above the melting furnaces and opening transom windows. The coppersmithing shop must also be separated from the other shops.

Heat treatment of metal and electric welding are performed in the forging and welding section. Even in standard-design workshops, forging and welding are intended to be carried out in the same room. The survey showed that exhaust extraction from forge hearths was largely ineffective because the fans were improperly installed, the exhaust stacks were too low and lacked deflectors, and the hoods were not appropriately sized for the hearths. During operation, the room becomes heavily smoke-filled, and carbon monoxide concentrations range from 0.0364 to 0.0756 mg/L. At certain times, when the hearths are being lit, concentrations may reach 0.105–0.3164 mg/L. In addition, the use of low-grade coal with a high sulfur content contaminates the forge air with sulfur dioxide. General shop air samples showed sulfur dioxide concentrations of 0.0082–0.0093 mg/L; samples taken 0.8 m from the hearth contained 0.01–0.016 mg/L.

Electric welding releases nitrogen oxides and manganese and fluoride compounds into the workplace air. Twenty minutes after work began, air samples taken 1.5 m from the welding site contained 0.0019–0.0021 mg/L of nitrogen oxides. Much higher concentrations may occur during more prolonged work.

Thus, our observations show that forging and welding should not be carried out in the same room. In addition, exhaust ventilation should be installed near the electric welder’s workstation, and extraction from the forge hearths should be improved.

Because nonstandard and obsolete standard-design workshops lack testing—

… station, engines are run in in the engine or assembly shop. This causes exhaust gases to accumulate in the room; we found carbon monoxide concentrations of 0.0488–0.2856 mg/L. When a tractor enters the workshop, the concentration of exhaust gases rises sharply, and the carbon monoxide concentration reaches 0.476 mg/L. This concentration persists in the air for 15–20 minutes after the engine is switched off. Exhaust gases also contain nitrogen oxides, gasoline vapors, lead, and a number of other substances. Engines should therefore be run in when most workers are absent, and the room used for running them in should be isolated from the other shops. When tractors enter the machine and tractor workshop, flexible hoses should be fitted to their exhaust pipes to carry the gases outside. Exhaust ventilation in the engine shop is highly desirable.

The engines of several makes of tractor and self-propelled combine harvester run on leaded gasoline, and washing fuel-system components in a washing unit does not completely remove carbon deposits from them. Shops that repair fuel equipment must therefore be fitted with exhaust ventilation. This also applies to standard-design workshops, where ventilation is not provided for in these shops.

The potential effects of all the harmful substances mentioned above on workers’ health have now become even more important in view of the establishment of a permanent workforce of machinery operators. In addition to sanitary and engineering measures, scheduled medical examinations capable of detecting the early stages of poisoning are of great importance. In our district, such examinations are conducted twice a year with the participation of physicians from two or three specialties.

Careful monitoring of machinery operators’ health, together with improvements in working conditions in the workshops, can substantially reduce illness among MTS workers.

Received February 15, 1957.