Upwind Site Research Articles

Variations of NO, NO 2 and O 3 concentrations downwind of a Los Angeles freeway

A sampling study was conducted to quantify the relationships of NO, NO 2 and O 3 concentrations with distance downwind of the San Diego freeway in Los Angeles. By continuously, monitoring at a site upwind (background) of the freeway and at selected downwind sites, patterns of NO, NO 2 and O 3 concentrations were detailed. Minimal separation distances of the samplers from the roadway to eliminate measurable influence were estimated to be approx 400–500 m for NO, NO 2 and O 3. A spatial model was fitted to the empirical NO and NO 2 data, which incorporated the effects of dilution, reaction and background level on measured downwind concentration. This model fit the experimental data closely and indicated that: 1. (1) the decrease of NO x downwind of the freeway can be expressed by a simple exponential dilution, 2. (2) the reaction of NO and O 3 downwind of the freeway is not well mixed and deviates from the ideal photostationary state, and 3. (3) the simple rate equations for the reaction of NO with O 3 and the photodissociation of NO 2 could be combined with a simple exponential dilution term to define the measured concentrations of NO 2.

Lead in human blood and in the environment near a battery factory.

Samples of blood, air, dust, soil, vegetation, and tap water were examined between 1973 and 1975 to determine whether a large battery factory (with a smelter) was contributing to lead in the environment and to lead absorption by the local population. Mean blood lead levels in the children of lead workers were about 6 μg/100 ml higher (P<0·001) than in otherwise comparable children. Capillary blood samples in wives of lead workers were 1·7 μg/100 ml higher (P<0·05) than those of otherwise comparable wives, but venous blood samples from the same subjects showed no significant difference. Lead in dust, soil and vegetation, although variable, decreased in concentration with distance from the factory. This relationship with distance from the factory was not however found in blood lead levels. No consistent effect of distance was found with lead in air, but significantly higher concentrations were recorded at downwind than upwind sites. The blood lead results have been analysed to assess the influence of domestic factors of possible relevance—such as, lead pipes, car ownership, age of house, etc. The presence of a lead-worker in the household appears to outweigh these other factors. The findings are consistent with the work of Burrows (1976) who showed that lead workers take lead home. An interlaboratory comparison on lead in blood was carried out. The two laboratories concerned were found to be equally consistent, but there were differences between them and the design of this comparison did not make it possible to say that the results of either were `absolute9 values.