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fuel. In some of these instances a method of diluting the flue gases has been installed and the
products of combustion have been discharged near ground level. As this does not affect the
ground-level concentration of sulphur dioxide it is not generally realised that other forms of
pollutants can be increased. These are in the form of oxides of nitrogen, some carbon monoxide
and an increase of carbon dioxide. There may also be a vapour nuisance. These pollutants when
discharged at low level in large quantities are likely to be prejudicial to health and this situation
is being kept under close observation with a view to preventing this kind of increase in atmospheric
pollution. Obviously this low-level diluted discharge has a specious appeal, in so far as
it enables some architectural problems of chimneys and costs to be pushed under the proverbial
carpet, but it is felt that this type of solution to a tedious problem should be viewed with a fair
degree of c?ution.
So far, those appliances that burn more than 1¼ million British Thermal Units per hour have
to comply with the Chimney Height Regulations, whilst those under this figure must be judged
on their merits and are subject, after their installation, to Public Health Act legislation It is a
fairly simple matter under the Chimney Height Regulations to ensure that large quantities of flue
gases are discharged at the proper dispersal height, but it can be seen that smallerappliances present
some difficulty as they can be dealt with only after their installation.
Measurement of Atmospheric Pollution
The measurement of atmospheric pollution has continued during 1969.
Daily readings are taken at the two volumetric stations to enable the concentration of sulphur
dioxide to be found, by the volumetric measurement of sulpheric acid which is produced when air
containing SO2 is bubbled through a solution of Hydrogen Peroxide.
Air is drawn from the atmosphere, through a filter paper, thus collecting small smoke particles.
This produces a grey coloured stain which by its density can give the quantity of smoke
in the atmosphere.