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(b) RAILWAYS
Railway engines are prohibited from emitting 'dark' smoke but are not subject to the grit and
dust emission provisions of the Clean Air Acts nor to a Smoke Control Order. THe Clean Air Act 1956
requires the owner of any railway locomotive to use any practical means there may be for minimising
the emission of smoke.
Since the changeover from steam-powered to diesel and electric locomotives during the past
two decades there has been a marked reduction in atmospheric pollution from smoke and other
pollutants. The same principles and conditions apply at an enhanced rate to the use of diesel oil for
railway motive power as they do for road traffic.
The overhead railway lines in the Borough include a small section of London Transport (electric)
and parts of three British Rail suburban lines (diesel) together with the main British Rail Eastern
Region (Northern Section ) line which traverses the Borough (partly underground) from Kings Cross
to Finsbury Park. The motive Power Depot for this Region is situated at Finsbury Park, in conjunction
with extensive railway yards and sidings, and would be the most likely source of nuisance from diesel
fumes in Islington. Locomotives refuel at this depot and the engines are parked on the sidings and
ignited prior to being brought into service. The ignition period takes only a few minutes and the
amount of smoke observed by the Public Health Inspectors who visited the depot when the process
was in operation was very slight.
Daily observations at varying times have recently been made from Isledon Road and no dark
smoke has been seen. British Rail, who operate a 24 hour service, appear to take all possible steps to
prevent pollution from diesel fumes. The Depot Manager stated that no complaints of fumes have
been received and there is no record of any complaints having been made to my Department.
Electrification of the suburban lines from Kings Cross is expected to commence within the next five
years.
In connection with the National Survey of Atmospheric Pollution, the Council maintains three
testing sites and, bearing in mind that one of the sites is approximately only 300 feet from the Motive
Power Depot, the following data is of interest. For comparison, the relative figures for 1962 are
shown in brackets as an illustration of the reduction in atmospheric pollution during the last 10 years.

* Seven Sisters Road.
These results indicate that the air in the vicinity of Isledon Road is generally cleaner in respect of
smoke and sulphur dioxide than in the other areas and that no adverse effect results from these diesel
emissions compared with the Borough as a whole. From the British Railways' point of view the most
important toxic constituents of diesel fuel are the oxides of nitrogen. These are easily monitored,
however, and the safe level is defined as 5 ppm. This limit is only likely to be achieved if diesel
engines have to be run in confined spaces for any length of time, e.g. during tunnel tests.
Benzpyrene (a carcinogen) is produced in measurable quantities only by engines which are
grossly over-fuelled or in a very bad state of repair producing heavy black smoke. The soot particles
in the smoke absorb the benzpyrene and it is not easily desorbed by body mechanisms. In other
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