Riding to and from the Cyclist office in Central London comes with all the usual benefits of cycle commuting but also all the drawbacks. Poor road infrastructure, a section of the motoring public with a disregard for the safety of others and pollution so bad on some days that you can almost taste it.

Promises from City Hall to 'make London a byword for cycling' are somewhere between ambitious and laughable. The newly launched Utra-Low Emission Zone is a step in the right direction but a small step in the grand scheme of the challenges faced by the country and the planet.

Those challenges have been taken on by a group calling itself the Extinction Rebellion. Making the lead story on most news outlets, readers will be aware of the protests taking place in London. Roads have been blocked and public transport disrupted.

The former approach, that is the blocking of roads such as Parliament Square, Waterloo Bridge and Oxford Circus among others, has had a positive albeit anaecdotal impact on cycling in the capital.

Waved through by the campaigners to ride on effectively traffic-free roads has made the cycle to and from work vastly better than normal.

An improved commute aside and whatever anyone's thoughts on the group or its tactics, about which we're not offering an opinion, the London Air Quality Network, part of King's College London, has found measureable impacts of the groups actions.

LAQN measurements of air pollution during the protests

The London Air Quality Network analysed the air quality effects up to Wednesday 17th April, which at the time of writing was the latest full day of the protests.

Hourly measurements of nitrogen dioxide concentrations were taken at sites across the London Air Quality Network (LAQN). These were taken from Monday 15th to Wednesday 17th April - the opening days of the protest – and compared to days of the week when London is running as normal.

The LAQN explained that 'the measurements used for non-protest days were taken from March, April and May to reduce the effect of seasonal variations in air pollution.

'Only measurements since 2016 were included to reduce the impact of any long term changes, whilst still including sufficient data to make a comparison.'

The above graph shows measurements from the Northbank BID site on the Strand, which is situated near to one of the key protests locations on the north end of Waterloo Bridge.

'Although the Strand is not itself blocked traffic was visually observed to be lighter than normal, although Easter school holidays may have contributed to this,' the report explains.

'Over the full day, nitrogen dioxide concentrations during the protest were about 91% of usual concentrations.' That near 10% drop will be noticeable for those walking and cycling in the area.

The next graph is taken from the monitoring station at the Westminster/Oxford Street site, near Selfridges.

Here, a larger reduction in nitrogen dioxide concentrations was recorded, and this is near to where roads are blocked at Oxford Circus and Marble Arch.

The reports adds, 'the section of Oxford Street next to the monitoring sites is not blocked but access is likely to be reduced.

'Over the full day, nitrogen dioxide concentrations during the protest were about 18% lower than usual concentrations at this location.'

It continues with the analysis and delivers the most impressive stat of the whole report: 'The reduction in hourly pollution concentrations was as much as 45% in the mid afternoon.'

Air pollution almost halved when motor vehicles were restricted from moving through key areas of Central London, in this case through non-official means.

Unfounded claims about increased pollution

A favourite go-to of the anti-cycling lobby is the baseless claim that cycle lanes cause pollution. Overlooking the emissions-free nature of the bicycle, those who like to downplay the benefits of safe, sustainable transport contest that cycle lanes take up space that could be occupied by cars, which makes the cars queue for longer, meaning they give out more emissions.

The air quality report highlights similar claims being made about the climate emergency protests, and so analysis was repeated for locations in areas neighbouring those affected by the protests.

'Some commentators have suggested that an increase in congestion and queuing traffic, or increased traffic in areas surrounding the protests may increase pollution concentrations in these areas,' the report continues.

'At Bee Midtown BID’s site in Holborn, to the north of Waterloo Bridge, there was very little change in nitrogen dioxide concentrations.

'Concentrations during the protest were around 98% of the usual concentrations. At Marylebone Road, to the north of Oxford Street which could be used as an alternative route for traffic there was a reduction in nitrogen dioxide concentrations during the protest.

'Concentrations were around 80% of usual concentrations on these weekdays.'

In fact, only one Central London location showed higher emissions, and the low level increase and this being just one measuring station could mean other factors were at play.

'At Euston Road, nitrogen dioxide concentrations were around 5% higher during the time when the protests took place.'

Things were less clear cut away from the centre of the city, with some stations showing increases but with little to indicate a clear connection to the protests. Although, of course, those insisting on driving by alternative routes could be increasing emissions in other areas as they attempt to circumvent the protests.

'It is not possible to directly attribute or exclude any of these changes as being due to the protest,' the report adds. To balance the analysis and present all the facts it goes on to say that, 'it is important to note that the protests are taking place at a time when traffic in London is often reduced as it is during the school Easter holidays.

'Therefore, reductions in pollution could also be expected for this reason.'

However, the impromptu road closures may have had an even bigger impact than the comparative data shows or could also be a drop in the ocean due to pariculate matter from other sources, as the report goes on to explain.

'A major pollution episode is taking place across London which would be expected to increase particulate pollution concentrations. This analysis has focused on changes in nitrogen dioxide concentrations, for which the main source in Central London is road traffic.

'Similar results would not be seen for particulate matter due to a pollution episode in progress, which includes local and imported pollution.' Further details of this can be found here: londonair.org.uk/london/PublicEpisodes

Summary: Closed roads reduce pollution

The report concludes that the measurements taken show at least some edvidence of a reduction in nitrogen dioxide concentrations at the monitoring stations near to closed roads.

As a result of none of the monitoring sites being located on roads where traffic is completely blocked, it's expected that 'reductions in nitrogen dioxide concentrations would be likely to be much larger where no traffic is able to pass at all as has been seen during other road closures.'

Another crucial point is reiterated, too. 'There is little evidence of any significant increase in nitrogen dioxide concentrations in areas neighbouring those where the protests are taking place.

'The difference in concentrations well away from the affected areas is inconsistent and reflects possible increases in pollution due to meteorological conditions, offset by the possible decreases in concentrations due to lighter traffic in the school Easter holidays.'

Photo: Julia Hawkins/Flickr