Research has shown that it is inadvisable to spray crops during either near-absolute calms or very windy conditions; therefore, we studied weather maps and reports of herbicide accidents to investigate the hypothesis that the strong positive correlation between largescale pressure gradient and wind-speed can be used to facilitate prediction of favourable spraying times in Oklahoma. We gave detailed study to the conditions of 10 May 1977, the date in that year when the most herbicide accidents were reported. Although a relatively large pressure gradient existed, there was only weak wind at the KTVY meteorologically instrumented tower (150 km distant from the area of the accidents). We also searched for a strong relationship between herbicide accidents and the pressure gradient through tabulations of daily gradients and accident reports. Only a slight tendency is shown for accidents to occur on days with larger gradients. Research and significant findings for this study were hampered by a lack of specificity and detail in accident reports.

Monitoring and evaluation of air quality in urban and industrial areas are essential for air quality management. For evaluating the composite air-quality in the concomitant presence of several pollutants in the atmosphere, many air quality indices have been developed. This paper presents two indices, the ‘composite air-quality index (I1)’ and ‘the standard-exceeding index of air pollution (I2)’ together with their respective sub-indices, for the pollutants monitored and for use in combination.

The first index, I1, is based on the annual average concentration measured in a year for each pollutant; it measures the overall composite air-quality. By relating the annual average concentration (Ci) of each pollutant to its hygienic standard (Si), as many (Ci/Si) values as the number of pollutant parameters monitored are found, whereupon I1 is computed as the geometric mean of the maximum and average of all (Ci/Si) values. A greater value of I1 means worse composite air-quality. It is simpler to compute than those more sophisticated ones in the literature, and holds the unique characteristic of considering, and yet not overemphasizing as formula (3) does (Nemerow, 1974), the maximum (Ci/Si) value.

Discussions on environmental implications of nuclear energy have so far been concentrated on radiological aspects: disposal of radioactive wastes, safety of nuclear power production, safe handling of plutonium, and problems associated with uranium mining. There are, however, several environmental issues associated with nuclear power production that are non-radiological in nature: thermal pollution and attendant effects on aquatic life, problems associated with land-use requirements, aesthetic considerations, habitat alterations, and atmospheric effects. These different non-radiological environmental implications of nuclear energy are reviewed.

The paper concludes that, while there are some environmental problems which exist at present, and a few more could emerge in the future, all these problems appear to be solvable with the present state of technological development. The extent of environmental degradation can be significantly reduced by appropriate design and planning.

Atmospheric pollution over cities accumulates under light wind or stagnation conditions and, on occasion, may be supplemented by transport from distant sources. These conditions cannot easily be predicted by use of the average weather elements. However, material which is useful to decision-makers who are concerned with air pollution problems can be obtained by presenting the data, as in the case of Durban, South Africa, first in terms of the nature and characteristics of vertical mixing in the lower atmosphere, and secondly in terms of the horizontal transport of air. In this way the nature and characteristics of surface and non-surface inversions and mixingdepths, as well as of macro- and meso-scale atmospheric circulations, can more easily be appreciated. In addition, a measure of the air pollution potential can be obtained from daily maximum mixing-depth and win-speed values.