Ozone in Los Angeles and Surrounding Areas A.
w. BARTEL, United States Rubber Co., Los Angeles, Calif.
J, w. TEMPLE, -United States Rubber Co., Detroit, Mich.
F
F o r some considerable time, it has been apparent that Since potassium iodide in OR a considerable time, it has b e e n a p p a r e n t rubber products exposed to the atmosphere i n the Los solution is photochemically Angeles area developed characteristic ozone cracking oxidized to iodine in the presthat rubber products exmore rapidly than i n most other parts of the United States. ence of light, the whole apposed t o the atmosphere in The accumulated data are compared with information paratus was enclosed in a the Los Angeles area develop cardboard box with openings surface checking more rapidly . available from other areas and confirm that the Los AngeIes atmosphere, during the period oi measurement, was o n l y f o r a i r inflow and than in most other parts of relatively high i n ozone. vacuum line. Tygon tubing the United States. Aplausiwas used for the inflow line. ble explanation would seem to be that ozone concenThe complete apparatus was assembled without difficulty in a casing suitable for transportatrations of the region are relatively high. Inquiry, early in 1949, failed to develop any information on surface ozone concentration and field operation. At the fixed Los Angeles laboratory, the source of vacuum was tions for the Los Angeles area, and it was decided to make a few a Hy-vac pump, and for determinations a t remote points, the orienting determinatiods; these were subsequently expanded to vacuum was obtained from the manifold vacuum line of the car. many, and the results are reported herein. I n most cases, sampling was for a 10-minute period a t the rate Determinations in meteorological circles by spectroscope or spectrophotometer deal with oione in the total atmosphere, with of 5 liters per minute. With this 50-liter sample, the titer for a 10 parts per hundred million ( lo8) by volume ozone equivalent the clear recognition that the great bulk of the measured amount in the sample is about 0.5 ml., and using a microburet, this was is in the stratosphere or above. It is generally considered that this stratosphere ozone is by far the major source of surface ozone, handled without any particular trouble. Replication. Most of the data of this report are from indivhich is brought down by convection currents and thereafter is subject to movement and decomposition from factors of weather, vidual, nonreplicated determinations. Consecutive runs had geography, photochemistry, and both natural and man-made indicated that appreciable variation of values can occur along the hourly time axis, and that replicates, if made, should be for contaminants of the lower atmosphere. It is not surprising that concentrations should vary from one location to another and from brief measuring periods. On several occasions checks made in replicate for two successive 10-minute periods yielded the followseason to season. On the basis of cracking bent rubber samples during warehouse ingpairs of results: 5.3,5.6; 28.8,24.4; 13.6,15.2; and 19,3, 18.7. exposure for 45 days (September 15 to November 1, 1949) Various oonfirmations of the general magnitude of the figures Nellen, Dunlop, Glaser, and Landes (9) rated the severity of were obtained from independent determinations made b y another agent. For exlbrnple, on August 24, 1949, the reported figure was cracking at a large number of locations. Typical ratings of 44 parts per hundred million. Data taken on the same day, a t severity, including the extremes, were: Santa Monica, 420; Los Angeles and Denver, 360; Long Beach, Calif., 230; Dallas 12:OO noon, by Stanford Research Institute (IS)are read from and Boston, 150; Washington, I).C., and Portland, Ore., 30; New its chart as about 40. York, Seattle, Atlanta, and Conshahocken, Pa.,
