Method of Evaluating Air Pollution in Tables and Maps

Abstract

The constantly deteriorating quality of the atmosphere, in particular in the cities and large industrial areas of Czechoslovakia, just as in all other highly industrialised countries, is creating conditions for serious damage in forestry and agriculture and, in extreme situations, also in the health of the population. Highly polluted air may, in certain cases, even act as a limiting factor of further industrial and housing development. In view of the high density of settlement in this country, it has become necessary to work out a review of air pollution on a national scale. This was a task presenting considerable difficulties, since the extensive material of terrain measurement was greatly diversified. This material provided by various institutions which carry out measurements of air pollution, was summarized after some slight adaptation in such a way as to furnish an overall picture of air pollution in this country. The resulting work consists of tables giving the basic data, for instance period of measurement, number of sites and of measurements in the individual areas, and annual dust fall averages in t/km2/yr. Data on the measurement of toxic gases, especially sulphur dioxide, are treated in the same way. In this case the average values are given in units of measurement according to the method employed - mg/m3 in case of short-term measurements and μg/hr, mg/wk, mg/day when a summation method is used. The average results of dust fall and gas concentration measurement for the given period (as a rule 1 year) are quoted in the tables in extreme values acquired from the various sites. Apart from this, they are also given for the whole measured area. The review is put together according to regions, areas and localities in alphabetical order and chronologically up to the year 1962, the data for every year (period) being given in one line. In maps the data were presented on a scale 1 : 200,000 for every region and 1: 750,000 for the country as a whole in a few copies; a year later (1963) they were printed on a scale 1: 50,000 and 1: 500,000. Isolines of average values according to a chosen classification scale are marked. Dust fall is given in t/km2/yr, dust fall of toxic nature being marked in a different colour. Isoconcentration lines of toxic gases are again differentiated by colour, separately for sulphur dioxide and for all the other toxic gases, in mg/m3. The dust fall isolines represent the individual classes of the chosen classification scale, the lowest limit of the scale being 50% of the highest permissible value according to hygienic instructions. The classification scale of toxic gases is formed by half and n-multiple of the highest permissible concentrations. This general expression was made necessary because in the hygienic instructions various gases possess different highest permissible values which, moreover, exist in two variants (short-term and long-term). As far as the method is concerned, the isolines of the classification scale were designed by interpolation of the average values of the individual sites in maps of 1 : 25,000 scale, and then reduced to the scale required. In the maps areas of organoleptically detectable odour are also marked, distinguishing industrial and agricultural odours. It is open to doubt whether this way of presenting data on air pollution by dust fall in tables and maps by this rather primitive metod in t/km2/yr is really suitable. It was made necessary, however, mainly because other kinds of measurement of pollution - for instance of concentration in mg/m3 - are few. In view of the lack of cleaning devices, which leads to the atmosphere in Czechoslovakia being polluted by large particles, this method of measurement is fully justified. In future, when the quality of dust changes and fine particles will come to predominate, pollution will have to be measured exclusively by its concentration.