Pollution Report

This was written in response to a pollution report brought out a few years ago in Britain. The measurements are based solely on ambient monitoring.

The NO_x values will not be decreased by the more widespread use of catalytic converters on vehicles. The present catalytic converter oxidises carbon monoxide and, to a certain extent, carbon in the presence of oxygen using a platinum catalyst to produce carbon dioxide. It has no beneficial effect on nitrogen oxides, but may, indeed, increase them slightly. There are not yet any effective methods of removing nitrogen oxides. The only useful way of dealing with them is to prevent their formation. This is best carried out by reduction of combustion temperatures and the avoidance of spark ignition systems. Petrol engines produce much higher NO_x levels than diesel engines. Quoting solely NO₂ levels hides a large part of the problem, especially if the sources are local. In many cases, over 95 % of the NOx emissions are nitric oxide (NO). Since present measurement methods assume that all the NO will eventually oxidise to NO₂, this can mean a level of NO₂ nineteen times the measured value at a point downwind. It will, of course, be diluted and therefore not be as obvious, but it is there.

Since both nitrogen dioxide and sulphur dioxide are highly soluble in water, fog and rainfall will reduce the ambient levels dramatically at the cost of increased levels in the ground and water supply. Using solely ambient monitoring as a benchmark leads to errors in this way, and the values for foggy weather or rainy periods should be either excluded or corrected.

The comments that over 70 % of the carbon monoxide is caused by traffic seems strange so long after the introduction of the catalytic converter for petrol engines. Are the converters not working, or are there so many vehicles which are not fitted with converters? Many countries charge a higher level of vehicle tax for vehicle not fitted with catalytic converters, meaning that these and diesel vehicles are indirectly promoted.

Most domestic appliances in the area will presumably use natural gas, so these are unlikely to be causing significant levels of CO, although the emphasis on checking for CO levels in the home is, frankly, suspicious. Why check for it if we can assume it is not there?

Derbyshire in general tends to be fairly windy, so most of the pollutants encountered are likely to be from other areas, and the pollutants produced in Derby are probably mostly encountered elsewhere. This makes the measurement of ambient conditions near the smoke stacks of Willington and Ratcliffe-on-Soar power stations irrelevant. Carbon monoxide and NO are not heavier than air and these sources will not be measurable at ground level in the vicinity. Earlier research showed that even the heavier molecules such as SO₂ and NO₂ produced by British power stations tends to descend in Sweden, which has made Britain very unpopular in Scandinavia.

There are no figures relating to the causes of the pollutants, simply figures about ambient levels with the implied assumption that they are produced locally and no suggestions about tracing the sources and, if economically viable, attempting to reduce or, at least, monitor them. In many cases, pollutants, particularly CO, are produced as a result of inefficient combustion, and there are substantial possibilities to decrease expenditure on fuel by improving efficiency.