WMOD00480 - Laserfiche WebLink

Home Browse Search

276 September, 1970 IR3 Type of driving Idle Deceleration Cruise Acceleration Percent volume CO Parts per million Muffler temperature, 0 F 5.2 52,000 500 5.2 52,000 500 0.8 8,000 700 4.2 42,000 900 Depending upon the operating mode, dilution factors varying from 20 to 100 are required to reduce the concentration of CO, as emitted from the exhaust pipe, to levels acceptable for periods up to an hour. The operating mode under which an individual is most likely to encounter high concentrations is, of course, idle. Under idle conditions in an ambient air temperature of 7(1' F, the concentration of CO in the exhaust gases at a point where the temperature is 15(1' F is slightly above 12,000 ppm. In an ambient air temperature of 00 F, the concentration at 15(1' F is over 22,000 ppm. As noted earlier, concentrations of 4,000 ppm or higher are fatal in less than an hour. Lead halides are present in automobile exhaust. It is used in gasoline in the form of tetraethyl or tetramethyl lead. The amount per gal of gasoline varies from 2 g to 4 g, depending on the brand and location where it is sold. Using an average value of 3 g of lead per gal of gasoline and considering a speed of 30 mph at a consumption rate of 1 gal per 15 miles, 6 g of lead, primarily chlo- rides and bromides (4) are released to the atmosphere per hr. Variation of cruising speed or gasoline consumption rate will alter this value in direct proportion. The toxic hazard of lead is severe if inhaled, especially if it is in soluble form and the particle size is between 0.3/-l-2.0/-l. With these characteristics it is retained and readily absorbed by the lungs (11). Much of the lead re- leased to the atmosphere as part of automobile exhaust is in this form. It has been estimated that the principal source of atmospheric lead as an air pollu- tant in urban areas is from the combustion of leaded gasoline (7). About 60 % of the atmospheric lead in the Los Angeles area has been shown to be less than 0,45/-l and 90 % is less than 1.6/-l (9). Because of the cumulative factor of lead absorption, the potential hazard of lead poisoning is high, its effects well known (5). COMPARISON SUMMARY A direct comparison of a silver-iodide generator and an automobile, both operating in an ambient air temperature of 7(1' F, with their effluents diluted to 1500 F, is as follows: Silver Iodide Generator Effluent. 1. Iodine vapor; concentration 0.47 mg per m3 of air. This is less than one-half the ACGIH threshold level: no hazard. 2. Carbon monoxide; concentration 150 ppm. This concentration canbe ac- cepted for at least 1 hr without effect: no hazard. 3. Silver iodide and complexes. Absorption is unlikely due to the relative insolubility. If absorbed, no constitutional symptoms will result: no hazard. ., I