Last week’s protest by farmers against changes to inheritance tax, involving tractors being driven into Westminster, produced a sharp rise in air pollution levels in the area, according to readings taken on the day.
Sensors on Horseferry Road, close to Parliament and government buildings in SW1, registered a spike on 11 December, the day the protest took place, in the level of nitrogen dioxide (NO2) in the atmosphere, taking it far above World Health Organisation (WHO) guideline levels.
Data was collected from two sensors, one of them part of a Department for Environment, Food and Rural Affairs (DEFRA) monitoring station, the other a smaller device in Imperial College’s Greater London Authority-sponsored Breathe London network
show the NO2 level peaking at more than three times the concentration the WHO advocates as a target for reducing illness linked to breathing in the harmful gas.
A graph of the Breathe London sensor data (below), gathered by Westminster Council officers, shows NO2 exceeding the WHO guideline of 25 micrograms per cubic metre of air for a 24-hour average from around 7am, reaching roughly 80 micrograms early in the afternoon.
The DEFRA sensor, which captures levels of all nitrogen oxides and other air pollutants, registered two spikes in NO2 levels around the time of the protest, the first matching the highest level seen earlier in December and the second greatly exceeding it (graph below)
In internal correspondence, a Westminster Council officer pointed out to colleagues that, “Across London, there are often spikes above the WHO guidelines due to various traffic or meteorological events,” but added that “the evidence of previous days” suggested that the spikes “can be directly attributed to the recent protest.”
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