Breathe London solar-powered wireless AQ monitor – close up on a lamp post on C9. These are Clarity node S sensors

As an off-beat way to mark the half-century since that iconic song Can the CAN topped the charts in June 1973, LBHF has sponsored air quality monitors that were installed on roadsides near a number of primary schools, and on the C9 cycleway in the last six months. The short and long-term numbers show that air quality isn’t very poor as claimed, suggesting instead that the Clean Air Neighbourhoods policy should be canned, or rather better, renamed and prioritised towards the basket of the other proposed environmental improvements in an unfortunately misnamed policy. With London Climate Action week around the corner, this is especially true when the extra miles, economic and other downsides of the proposed LTN’s are considered.

The policy aims to improve the overall environment in H&F, and who can deny that’s a good idea? But the unnecessary LTN part of the policy is likely to make the air worse in the worst hot spots, and the PR fails the fact-check, which we explore further below.

Our interactive map of ‘BreatheLondon’ sensors coloured by sponsor, May 2023. Click for more detail

50 monitors in H&F were supplied by Breathe London, as part of a 430+ fleet across London supported by Imperial’s ERG (Environmental Research Group). When they produce data, which can be intermittent because they’re radio linked, they appear to give reasonably consistent results in line with the council’s ‘regulatory’ stations HF4 and HF5 at Shepherds Bush Green and the Broadway, plus a new one, HF7 by Frank Banfield Park, which are run professionally by Ricardo Environmental.  Those stations are rather more sophisticated and reliable, covering more pollutants than the NO₂ and PM2.5 measured by the new monitors, which are nevertheless of most interest. We’re told that the council is also supplementing these with a private network of sensors, details of which are unavailable, though this from 2021 turns up in searches. In this article, we set the scene for an ongoing citizen science project, building on a previous article

A good news story

Long Term AQ Trends 1970-2020
[ Chief Medical Officer’s 2022 Air pollution report ]

Contrary to many reports, since the H&F Air Quality commission first reported in 2016 (and the 2015 publication of the KCL report the council relies on), average nitrogen oxide levels in the borough have nearly halved, in line with the national figures shown adjacent. The decades-long steep straight-line downward trends previously described, suggests a proportionate and realistic plan is needed to address causes of the remaining local issues, rather than the imposition of unhelpful LTN’s.

PM2.5, though a quarter of the level it was in 1970, is still said by the WHO to be the main concern. While the council’s CAN page describes a good range of issues, it relies on short term pandemic-skewed data to shore up a fragile argument, ignoring long-term trends. If the graph adjacent represented rates of infant mortality, road accidents, heart attack, cancer rates or obesity, everyone would be singing from the rooftops, celebrating such a great success.

‘Clean Air’ vs. Roads

Vocal social media campaigners, sections of the traditional media, the Mayor of London and LBHF have expended a lot of effort and no small amount of money, alarming you with declarations such as “Toxic air is a matter of life and death, causing around 4000 premature deaths every year in London”, calling it ‘deadly’. On the same topic, there’s the Mayor’s ULEZ, and its planned expansion this August. But,

London has the cleanest air since 1585

That was said controversially 22 years ago, long before ULEZ, expanded ULEZ, or even the Congestion Charge, when nitrogen oxide pollution was about three times the level it is today, yet already lower than it would have been in Shakespeare’s time, but it’s still not good enough for some diehards, and we still have the most congested city in the world making everyone’s lives more difficult. In support of  Clean Air Neighbourhoods, LBHF recently claimed that ‘because the air across the borough is of very poor quality, we need to take immediate action’.

But it’s not the air that’s very poor quality, it’s the somewhat alarmist and unconvincing argument. Pollution in the borough, as most of the UK, is classed by DEFRA as ‘low’ over 96% of the time, the remaining 4% being attributed to PM2.5, largely unaddressed by the CAN policy. The council says it knows better, calling the air ‘filthy’ and ‘poisonous’, and suggesting that the increasingly stringent national and international regulations that have been so demonstrably effective for 30 years will somehow cease to be effective now – unless we have LTN’s.

It’s not that there’s no pollution, it’s that the graph above shows nitrogen oxide pollution falling towards background levels in the next 10 years with no evidence it will stop falling, certainly below WHO latest 2021 guidelines, and that vehicle NO2 pollution must fall further as EV’s take over. According to Public Health England, 88% of the concerning particulate pollution is unconnected with the target. Such ‘Clean Air’ measures can then be framed as a backwards-looking policy, wasting precious council funds and your time, while barely addressing the important sources, and yet unnecessarily hampering businesses and life in general, especially for those trying to do better, by investing in an EV, or even better, using public transport.

A pilot scheme runs in South Fulham (TCPR), on which the council has doubled-down, describing it as ‘successful’ by saving just 1 tonne of CO2 daily – of a total 300,000 (while not counting extra miles driven, or seen in LBHF). Unfortunately, despite the new sensors, conspicuously absent are claims of measured air quality improvements – the name on the tin.

As a result of the debacle at the TCPR, there’s been a 1500-strong petition in the next target area, and leader’s own patch, Brackenbury, and as a result it’s been widely reported that Better Brackenbury are no longer campaigning for this policy – or specifically the LTN part of it – and it won’t proceed there.  The problem may have been that a) the unfortunate name and associated PR polluted the better parts of the policy, and b) Air Quality was being conflated with traffic dangers in a one-size-fits-all approach, whereas an EV poses as much pedestrian danger as a diesel car – a key local concern – but rather less pollution.

Then there were the forty or so businesses who expected to see their livelihoods suffer as 76 out of 84 polled in South Fulham have. Some report income declines of 38% since the TCPR, many report profits turning into significant losses, and some, including nearly all the builders merchants in Carnwath road, are planning to move out after residencies of up to 40 years. Damningly, a common sentiment is that TCPR is worse than COVID.

Unfortunately there’s also a real possibility that this is a simple old-fashioned cash-grab, as regularly suggested in the media. The Times reported last month via FOI, that LBHF is a parking fine hotspot, (the mechanism also used to charge transgressors in the TCPR and other planned CAN’s), and third highest earner in the country, earning a staggering £18.9 million last year (£103 per resident), equal to 15% of it’s net expenditure budget. As Ella’s mother says “The coroner recommended they monitor & inform people about the air they breathe. Instead they shut roads & create mayhem & milked the public for their money. AQ has steadily got worse, disgraceful!”. The AQ mentioned of course referring to main roads where she lived at the time Ella died, and which she now says local LTN policies are worsening.

We commend LBHF for doing the first half of the job, but for quite a few years, air quality hasn’t been about the NO₂ in back-streets. Below we look into the four significant AQ issues.

Everything in proportion

Despite a background level that’s been present forever, the WHO and others are now being widely quoted as saying that there’s no safe level of air pollution, which is unfortunate because quite a few daily activities that might have been familiar to Shakespeare, such as cooking, washing clothes, vacuuming or sweeping the floor, or using more recent inventions such as so-called ‘air fresheners’ or perfumed detergents, plus a long list of others, generate significant and persistent air pollution at home – sometimes a surprising amount – which means we’re all going to die. But as adults, we knew that already.

We’re not speculating on what is so-called ‘safe’, ‘unsafe’, ‘clean’, or ‘dirty’ (unhelpful binary social-media constructs), for the reasons that a never-before-seen ‘zero’ is being widely called for, the WHO have moved the goalposts substantially recently – though not to an impossible zero – and central government is consulting on a new strategy to which we contributed.

We deserve a more sophisticated debate than an overly toxic and infantile “clean” vs. “dirty” binary campaign, but rather than address the actual issues, local government is determined to make it largely about road transport – their predetermined bogeyman – in the face of the clear long-term trends and effective measures, and the worldwide nature of relevant sources.

Names matter

“Flora Gardens Primary School” AQ sensor – Dalling Road. [Photo: BreatheLondon]

Following on from the unfortunately named CAN policy, despite site names, the LBHF-sponsored sensors are not actually in primary schools, they are roadside on lamp posts, somewhere near primary schools, and that makes a significant difference. They, like some infamous politicians, are not quite inhaling what they claim. The photo adjacent shows a typical one, here named “Flora Gardens Primary School”, but actually on a lamp post in Dalling Road, as you can see. The raw data shows this.

For those interested, DEFRA publishes a spreadsheet calculator to calculate the reduction in NO₂ with distance from the roadside (PM is another matter, as much as 80% windblown so not easily determined). NO₂ figures from these detectors need normalising with such a calculator to represent the levels in the vicinity and especially within the named schools, which will be significantly lower – perhaps 30-40% lower – than roadside. Concerned parents take note. 

This sensor might be more accurately named ‘Dalling road south’, as ‘Thomas’s Academy’ would be named ‘New Kings Road’.  But they could actually be put in schools as some other boroughs do, which you can see by checking sensor photos linked to our interactive map above.  Ideally they would be in pairs, inside and out, to make a school science project out of comparing the daily activities that affect readings. Recognising this, there is already a related ERG project called ‘WellHome‘, and there’s the SAMHE project for schools – their monitoring doesn’t mention NO₂

Searching through the megabytes of data in the Mayor’s London Datastore, one can find the actual and future modelled figures for Flora Gardens as an example:

NO₂ – this policy’s main AQ target – is expected to continue its 30-year long fall regardless – near halving again in the next decade – as it has in the last one – approaching background levels, whereas the problematic and largely unaddressed PM2.5 is falling rather more slowly, though it’s going in the right direction.

Out of the 84 schools in H&F modelled, only one (unsurprisingly St Paul’s CofE Primary School at the Broadway) exceeded the WHO’s extant NO₂ recommendations in 2019, and then by just 0.5%.  In 2025, using the WHO’s very much stricter guideline levels from 2021 (values of 25ug & 5ug), Just 2 schools: St Paul’s C of E Primary and Sacred Heart are predicted to marginally exceed NO₂, but all will exceed the tighter PM2.5 recommendation. By pushing traffic onto main roads, this policy would only make the situation worse in these most adversely affected locations.

The curious case of the Hammersmith wood burner

Averages are wonderful things, until they tell a story that masks the truth, For this reason, the WHO has both short term (24hr) and  long term (annual) guidelines – and they are just guidelines. That should cover it, right ? Perhaps, but let’s look at the curious case of the Hammersmith wood burner. At the start of the year we added live data feeds to the website selected from the above sensors. These aren’t 24hr averages, nor annual averages, but hourly spot measurements. This turns out to be useful for spotting something unusual. 

In Hammersmith we appear to have four problems:

1. 

   Air Quality 1am Saturday morning

   Local wood burners, in cold weather and regularly at weekends, particularly Friday nights in winter.  This is a factor that really skews our local AQ statistics.  The same (Friday) that the ‘Brackenbury Primary’ feed arrived on our website as part of our citizen science project ahead of the proposed LTN, later that same evening, the numbers went through the roof. It transpires that we’re not alone

   What was so instructive was that not that it could be smelt by the Mk.1 nostril – no tech required – but that the regulatory stations HF4 and HF5 on busy main roads were unmoved, as you can clearly see.

   The pollution was caused by PM2.5, and was very local to backstreet residential areas. There was almost no traffic on the road – obviously – data shown was recorded at one o’clock in the morning!

   By daybreak, normal levels prevailed.  Sometimes a similar effect can be seen when a local activity, for example caused by building activities (planning consents recognise this and now usually mandate AQ management plans), or even a BBQ, cause airborne pollution to be raised for a short time. Its wise to be careful not to exaggerate one-off events, but similar readings across a range of sensors – as here – can point to something of significance.

2. In some hotspots right next to main roads, we have current NO₂ issues, particularly when traffic grinds to a halt – we listed those before, and suggested that rather than the council gumming up main roads with more restrictions such as LTN’s, keeping them moving would be a Good Thing. In London, buses still transport ten times more people than – dare we say it – cycling, in a very economically and increasingly environmentally effective way. Especially for those less able – as long as they can access them, they are timely, and not emasculated on the altar of noisy social media campaigns. Giving over bus lanes is seen as regressive by a significant portion of the population.
3. 

   Air Quality, Feb 13 2023 [ IQAir ]

   PM2.5 pollution created by widespread and predicted atmospheric conditions, or imported from other parts of the world, which then appears uniformly across all stations. We know that unusual weather conditions, such as occurred last summer, sometimes cause roofs to be covered with sand from the Sahara, but more frequently, wind blows PM from southern Europe, closer and farther afield too, such as the from recent Canadian forest fires, already showing up on the prevailing winds – and the sensors. This is when you get an Airtext alert indicating poor air quality several days in advance (the 4% above). Checking a map of the world: the adjacent example from 13th February shows that rural France, Cornwall, the Northeast coast, West Wales and much of Ireland were as polluted as London – and that was predicted and alerted 2 days earlier, on the 11th.

   

   Easter ‘AirText’ alert

   

   Air Quality, St Georges Day 2023 [ IQAir ]

   Another example occurred on Easter Sunday, and alerted on Good Friday by Airtext.

   

   Easter Sunday AQ

   Even if the unpredictable roads were the source, closing yours clearly isn’t going to help, and would be likely to increase CO2 emissions as all journeys, including those by bus, get longer and slower. 

   We should also look at the opposite case for completeness. Here, as if to mark St. George’s day, rural middle England is ‘moderately’ polluted, but 100% of London and most of the rest of Western Europe is ‘low’.

4. Heat derived pollution. Previously, we mentioned the effects of sun and to some extent domestic boilers on nascent atmospheric pollutants such as ammonia from agricultural sources which is the one pollutant that hasn’t fallen significantly since the 1970s – PM2.5 can be created from these sources. Little we can do about that – locally – other than reduce the heating, or move to a non-burning option, which is the medium term government plan.

Changes over a day

Air Quality : Morning : 22 Feb [ IQAir ]

Air Quality : Late afternoon : 22 Feb [ IQAir ]

These two graphics show how normal weather can affect PM2.5 pollution. In this case, as the prevailing wind blew in from the west, the pollution receded eastwards across the whole of Western Europe and North Africa, and London went from yellow to green in the space of a few hours – just by natural progression of weather patterns. Warm weather often reduces this air movement, so any pollution may hang around longer.

The Problem

Underground Pollution: Central Line vs. Shepherds Bush [@PeteK_AQ]. The Central Line is equivalent to the most polluted city in the world.

A short step into the toxic politics of predetermined cause and effect, and road transport is the identified problem – almost always cars – making no allowance for significantly rising EV numbers, particularly buses, forgetting those diesel-powered commercial vehicles and taxis, the “genuinely filthy” deep tube trains (shown adjacent), domestic heating – particularly local wood burners – agriculture, air transport, oil exploration and notably worldwide shipping.

As shown, these turn out to be overwhelmingly responsible for actual air quality issues, which for most of us is PM2.5, and on which, despite getting a passing mention in the policy, they should be taking far more action.  The council’s mantra, following City Hall’s diktat, is that somehow randomly closing this road or that helps, whereas these are tiny factors swamped by the global factors above, likely having no measurable benefits, but at the same time placing significant inconvenience and costs on businesses, the environment – via increased CO₂ emissions – and of course you.  This is not to advocate for cars, just for a policy addressing the actual sources, and rather less Fear, Uncertainty, and Doubt – of which we have enough already.

We’ve been archiving the raw data from across London, the rest of the UK and Western Europe for some time, and will be more deeply analysing cause and effect to create useful information from the data in part 2 if necessary; checking the effects of road closures before and after, should the council still decide to continue with the unfortunate LTN’s.