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Chiswick Air Quality and Cycling: Published Facts

It may be helpful if current opinion in Chiswick could be better informed by published data relating to air quality in Chiswick, cycle use and cycle safety. LB Hounslow publish an annual report on air quality and there are three monitoring stations on Chiswick High Road.  There has been year-on-year improvement along the High Road and in the 2020 report (from survey data in 2019) the levels of nitrous oxide were recorded as being at the level regarded as acceptable by both the EU and UK Government standards.  Hence, contrary to what councillors of LB Hounslow often pronounce, air pollution is not bad in Chiswick.  It could be better and the improvement trend should continue with the advances in vehicle engine technologies.  Regrettably the almost constant congestion of recent weeks due to the vehicle access restrictions and a lack of capacity on the High Road have probably increased the pollution levels. LB Hounslow regularly justifies it highway measures through a perceived need to increase cycle use.  However, TfL data published in the Council’s own Cabinet report in September 2019 states that cycle use in Chiswick is in the top 5% in London and is the highest in Outer London.  Chiswick hs a very active cycling environment and has been so for many years.  LB Hounslow could perhaps spend it’s money more effectively through encouraging cycling in the many parts of the Borough where the need is greater and where the benefits of active travel are less accepted.In the same Cabinet report in September 2019 LB Hounslow reported on accidents involving vehicles with cycles over the previous 5 years between Heathfield Terrace and Chiswick Lane, the busiest part of the High Road.  In this period, thankfully, there were no fatal collisions but there were two classed as serious and seven classed as slight. While any injury is something to be avoided the published data suggests that accident rates along the High Road have probably not been exceptional year-on-year, especially in the light of the levels of cycle use within the Chiswick area. 

David Kerr ● 2170d18 Comments

Thanks for this, David.

Claire Moran ● 2170d

Could I just point out that the lower pollution figures for 2020 might have something to do with the fact that we were in lock down from March to May and there were hardly any cars on the road.

Chris Blackwell ● 2170d

Hi David,Where do you see that the levels in Chiswick are acceptable? I agree that the nitrogen dioxide levels are falling from 2018 but still exceed the Governments acceptable level of 40 per the Air Quality Std Regs 2010. A more useful comparison is to compare it to other urban and roadside monitoring stations where the average is somewhere between 20 and 30. I think what you mean to say is that at no point was the legal limit of 200 broken. The last time it was breached in Chiswick  was 2017, on 12 separate occasions.

James Carter ● 2170d

"In the same Cabinet report in September 2019 LB Hounslow reported on accidents involving vehicles with cycles over the previous 5 years between Heathfield Terrace and Chiswick Lane"What specific document are you referring to?From the police collision reports, here are the figures for cyclist casualties in the 5 years from 2013-2017 in the section where the protected lane has been built (from CHR/KingSt to Heathfield Terrace)Row Labels Serious Slight Grand Total2013 3 32014 1 12 132015 1 5 62016 1 6 72017 2 3 5Grand Total 5 29 34I can provide the police collision report reference for all 34 casualties.For reference, there were 18 pedestrian casualties in the same section of road over the same time period.The CHR/King St junction is the top location for cyclist casualties in the entire route.Happy to update these figures with 2018 and 2019 but I won't have time until the weekend.The source data is all available from https://data.gov.uk/dataset/cb7ae6f0-4be6-4935-9277-47e5ce24a11f/road-safety-data

Michael Robinson ● 2170d

I am only quoting figure published by Councillor Khan in his Cabinet Paper for consideration on 3rd September 2019 - a matter of public record.The air quality report of 2020 refers to datas from 2019 and there is no lockdown impact.

David Kerr ● 2170d

There are 19 cabinet papers on cycleway 9 published for consideration on 3rd September 2019 - can you say which one you are referring to?

Michael Robinson ● 2170d

David, While NO2, NO and NOx have been falling due to improving engine design, as you said, they are not by any means the most hazardous pollutants for health. It's particulates, particularly the finest PM2.5 category that do the most damage, some 80% of the health costs of pollution in terms of premature deaths and health treatment. These amount to around £40m a year for Chiswick based on the London average, and this is probably an underestimate. If we look at the pollution counts on the High Road, we have been above WHO healthy levels for PM2.5 every year up to lockdown. Since then we have been averaging below this limit of 10 µg/m^3. This is simply due to the reduced number of vehicles on the High Road, not the improvement in vehicle technologies. If we are going to reduce the health costs of pollution, as well as environmentally damaging  emissions, then there has to be a reduction of traffic along the High Road. That is what a shift to active transport aims to achieve.

Tom Pike ● 2170d

Here we go again Tom. So you say:'there has to be a reduction of traffic along the High Road'Which means you believe a fall in traffic there will reduce pollution and improve health on that stretch of road. So what about those other roads which see significant displaced traffic, many of which are already busy and congested and therefore where residents suffer from the pollution. They actually suffer directly as a result of these schemes and road closures. We have seen the new bus gate increase queues along the west end of the High Road, an area with many flats and more under construction. Same is true of the stretch of High Road by the bus garage and up Goldhawk Rd, or Acton Lane. This is a point very clearly raised by Ealing MP Rupa Huq but studiously ignored by Hounslow and other lobbyists. PS: please answer without use the traffic evaporation fairy tale.

Paul Green ● 2169d

The particulate emissions of any sort of car less than ten years old is practically zero. Most of the exhaust based emissions of particulates on Chiswick High Road are now coming from lorries and vans on which the filters are not effective as those on cars. Bus emissions of this kind will also have dropped significantly because of the Low Emission Bus Zones. As someone pointed out on here previously traffic jams might actually reduce bus emissions because the hybrid buses stuck in traffic only use electric power with their diesel engines only kicking in when they pick up speed.Any number on the health costs of transport based pollution needs to be offset by how changes are paid for because there is a higher correlation between income than air quality when it comes to life expectancy. If you improve air quality by making people poorer then you probably won't be reducing health costs.

Mark Evans ● 2169d

You are conveniently forgetting about brake, tyre and road dust, which contribute approximately 50% of driver-caused particulate pollution.https://www.bbc.co.uk/news/business-48944561

Ken Munn ● 2169d

I didn't forget, I specified exhaust emissions. Working out how much of the pollution comes from non-exhaust sources is very difficult but it is likely to be more correlated to speed reached and distance travelled so, while not dismissing it as a general concern, it is unlikely to be anywhere near 50% of emissions on the High Road. The particles emitted are also generally not the very fine ones that come from engines which are generally recognised to do the most harm to health.

Mark Evans ● 2169d

On the question of the relationship between speed and brake/tyre/road dust you're right, so the more slowly drivers move down the High Road, the better.On the question of deleterious health effects, suffice it to say that experts don't agree with you.

Ken Munn ● 2169d

Experts agree and disagree on about everythig these days Agree ?

Julian Pavey ● 2169d

It will be obvious to most that slow moving traffic generally does not mean reduced pollution.I thought it was generally accepted that the finest particles were the worst for health because they get retained in the lungs. Non-exhaust vehicle emissions tend not to be of this sort but if you can cite research that contradicts this please share.

Mark Evans ● 2169d

You could start here...Environment Minister Thérèse Coffey said : “The documents published today make clear that it is not just fumes from car exhaust pipes that have a detrimental impact on human health but also the tiny particles that are released from their brakes and tyres."

Ken Munn ● 2169d

Thérèse Coffey is not an expert and her statement has confused you. These dust particles are tiny but they are not generally of the microscopic size that come from diesel emissions that are universally held to do the most damage to health. They will cause problems for people that have pre-existing breathing difficulties but whether they are a significant factor in the quality of air on Chiswick High Road is difficult to say. Unfortunately as electric vehicles emit them as well they are likely to be a constant factor.

Mark Evans ● 2169d

'Although brake wear particles are emitted as a result of a predominantly mechanical process and are expected to lie into the coarse size fraction, there are many studies which report high particle concentrations in the fine and ultrafine fractions (Iijima et al., 2007; Riediker et al., 2008; Wahlström et al., 2010b; Kukutschová et al., 2011). Garg et al. (2000) conducted brake dynamometer tests in different brake pads and found that 86% and 63% of the brake wear airborne particle mass was distributed in the PM10 and PM2.5 fractions, respectively. They also noticed that a considerable 33% (by mass) of airborne wear particles lied into diameters smaller than 0.1 μm. '

Ken Munn ● 2169d

I stand corrected.It remains a reasonable assumption however that the generation of brake wear particles would occur at a far higher rate when vehicles are decelerating from high speeds so the contribution they make to particulate pollution on CHR may not be that high. Even if it is - it isn't something that can be got rid of with current technologies.

Mark Evans ● 2169d