Wood burners or diesel vehicles – what’s behind London’s air pollution ?

Posted: January 29, 2017 by oldbrew in atmosphere, opinion

Bad air day in London [image credit: BBC]

Bad air day in London [image credit: BBC]

At one time diesel vehicles were given tax concessions in the UK due to lower emissions of CO2 than petrol equivalents, but that tide is turning now.

London’s pollution problem worsened this week – so much so that it briefly overtook Beijing in the filthy-air department for the first time – an alarming development widely attributed to the rapidly growing use of household wood burners, as iNews reports.

Readings on Monday afternoon showed that the air in parts of London contained 197 micrograms per cubic metre of ‘particulate’ matter, compared to 190 in the Chinese capital.

Dwarfed by human hair

Particulates are miniscule specs of dust, heavy metals and other fragments generated by diesel engines, manufacturing and central heating – the most deadly of which are less than 40 times the width of a human hair. These particles reach deep into the lungs and bloodstream, causing problems such as asthma, heat disease and strokes and responsible for an estimated 29,000 premature deaths a year in the UK.

The other major source of pollution is nitrogen dioxide – mostly from diesel vehicles, aviation, industry and railways, but not wood burning – which is behind for an estimated 11,000 early deaths a year in Britain.

As the London smog hit the national headlines, with schools hauling children in from the playground and Mayor Sadiq Khan taking to Twitter to bemoan “the shameful state of London’s toxic air”, many were blaming wood burners for the spike in pollution.

What is the culprit?

But was wood burning really to blame? The smoke escaping through the capital’s chimneys contributes around 5 per cent of the city’s particle pollution over the course of a year, according to King’s College London pollution expert Gary Fuller – noting that public health effect of wood burning is exacerbated because so many of the fires are in residential areas, increasing people’s exposure.

This figure jumps about considerably during the course of the day and the year – rising to around 10 per cent or more on particularly cold, still winter nights, when it’s late and the traffic has died down – and falling to virtually nothing in the summer.

“Wood burners are a serious and growing environmental problem that looks likely to get much worse in the next 20 years. They are already contributing to thousands of premature deaths in the UK each year – a number that is set to rise considerably between now and 2035,” said King’s College London air quality Professor, Martin Williams. He said that “very preliminary” findings suggest that by 2035, wood burning from households and businesses will have roughly doubled in London.

Data on wood burner pollution outside London is thin on the ground, although with wood burner ownership so much lower away from the south east it is regarded as less of a threat. But the problem is likely to spread across much of the country in the next 20 years, as wood burning looks set to steadily increase.

“People should think twice about burning wood because the particle emissions are much higher than using gas or electricity,” Prof Williams said.

Air pollution campaigners agree that wood burning is already an issue in parts of the country – and one that is set to spread. However, they point out that particles from wood fires are only responsible for a few per cent of the health problems stemming from London’s air pollution – and considerably less across most of country.

And even if the number of particles doubles, campaigners say the primary focus must remain on diesel vehicles, which are responsible for around half of the total air pollution in London and similar levels across much of the UK.

“While we need to tackle all major sources of pollution, including that from wood burners, we should not lose sight of the fact that the illegal levels of air pollution in our towns and cities all year round comes overwhelmingly from road traffic, in particular diesel vehicles,” said Andrea Lee, an air campaigner for the environmental law firm ClientEarth.

The iNews report continues here.
– – –
A Transport for London technical paper says:
‘On average, a diesel vehicle will emit 22 times as much particulate matter and at least four times as much NOx as a petrol equivalent.’

  1. oldbrew says:

    iNews also reports:
    ‘The burners are much more popular in London and the South East, where an estimated 16 per cent of households have them, compared to less than 5 per cent in Northern England and Scotland.’

  2. rms says:

    Steve Milloy’s book “Scare Pollution: Why and How to Fix the EPA” is an important book to read before jumping to too many conclusions about London air pollution.

  3. rms says:

    Also, what air pollution laws/regulations are being violated, by how much? Again,needs to be understood and communicated before jumping to conclusions and actions.

  4. David Ashton says:

    My niece’s husband jointly owns a company which manufactures stone fire places, but also supplies and installs all types of fireplaces. They cannot keep up with demand for wood burning stoves. Quite simply, people are finding their fuel bills too high and believe they can scavenge wood to reduce their costs. The business is based in the North West of England.

    With regard to particulates and asthma; a while ago I saw a map of the UK colour coded to show regional asthma rates. It surprised me to see that East Anglia had a very high, if not the highest, incidence. This suggested to me that agricultural activity, probably pollen or a particular types of pole, have as much effect as car emissions.

  5. Bryan says:

    But think of the CO2 versus Particulate issue the way a climate warmist does.

    CO2 increases for Petrol against Diesel option for the same car journey.
    Wood Burning Stoves utilise a renewable fuel but produce more particulates than gas central heating
    Particulates are generally thought of as a cooling agent in the climate.
    So for a Warmist the choice is easy, its good to use Diesel cars and Wood Burning Stoves.

    Unfortunately the WB Stove will kill a few thousand extra people – but hey that’s also a cooling tendency.

  6. scute1133 says:

    I thought the 1956 clean air Act was still technically in force but its Wiki entry says it was repealed in 1964, perhaps because it had the effect of encouraging gas and Electric. The 1956 Act was directed at households mainly burning coal but the Wiki entry suggests it included wood because only smokeless fuels were allowed.

    The 1968 Act, cited as a follow-up to 1956 in Toxipedia was just for industrial power plants. So it seems burning wood is legal. I really would’ve thought they’d have kept the 1956 Act operative for the very reason that unforeseeable future prices/fashions might prompt a resurgence of coal or wood burning. However, in 1964 it would’ve been considered regressive in Wilson’s era of “White heat of technology” (not actually said by him).

    Re the diesel infatuation (because it was supposedly climate friendly) I arrived in an almost empty supermarket the other evening. When I opened my car door I was knocked sideways by billowing fumes of diesel smoke coming in. And a rumbling chugging sound like a Chieftan tank coming down the way. When I looked it was a tiny Mercedes box car about a foot longer than a Smart car, just started up and reversing out. The cold evening air meant it was running inefficiently and all the smoke was hanging in the air below waist height. Literally nauseating. This is how far the fanaticism has gone. It’s an entirely inappropriate engine type for such a small car. But the incentives must’ve added up in favour of such folly. We have Tony Blair to thank for that.

    One more thought: I go to central London regularly and never smell the same nauseating diesel smell as I do in the suburbs. It must be because of the emmision zone. It may be costly but the situation at slow-moving juctions and traffic jams in the suburbs is beyond intolerable. ‘Beyond’ because some don’t tolerate it and drop dead.

  7. Joe Public says:

    @ Bryan says at 10:52 am

    “Wood Burning Stoves utilise a renewable fuel but produce more particulates than gas central heating”

    Stoichiometric combustion of natural gas produces no particulates.

  8. Joe Public says:

    Wood burners & clean air.

    It seems these two missives now apply:

    DIRECTIVE 2008/50/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 21 May 2008 on ambient air quality and cleaner air for Europe


    Protocol to Abate Acidification, Eutrophication and Ground-level Ozone
    The 1999 Gothenburg Protocol to Abate Acidification, Eutrophication and Ground-level Ozone


  9. oldbrew says:

    Government facing legal action over failure to fight climate change

    Lawyers say ministers have been in breach of legal requirements to come up with a plan to make major cuts to the UK’s fossil fuel emissions for years – and further delays in its publication could be the final straw

    Wasn’t the UK supposed to be leading this imaginary ‘fight’?

  10. Steve borodin says:

    The measure of ‘premature’ deaths is an emotional and misleading measure. It is composed largely of people under the age of 86 who die of some respiratory disease, when it is assumed that particulates MIGHT have contributed to some degree.

  11. Paul Vaughan says:

    People were reprehensibly naive about “new clean diesel” marketing.

    People are still naive today. For example people think the leadership the world needs right now is going to come from the US. This line of thinking is just as naive.

    Naivety backfires. Diesel is dirty and the solutions to the world’s problems will come from outside of USA (doesn’t matter whether Donald or Bernie’s in charge, solutions will come from outside…)

    With the extreme level of infighting going on in the US, it’s a complete no brainer that any “solution” there will be unstable. We’re on course for more suffering if we believe in exhausting ourselves with infighting to achieve only a fragile “solution” that can be torn down 1 or 2 elections from now.

    The real challenge is to pursue enduring stability that makes good common sense.

    For example it makes good common sense to be prepared each winter to stay reliably warm. It’s just common sense and it isn’t appropriate for governments to interfere with the basic right to plan to stay warm in winter.

  12. Robin Heath says:

    I’ve been burning wood in stoves since 1976. To me the most interesting thing about your report is that in all the reportage and subsequent comments there has so far not been a mention of the very major fact that the moisture content of the wood is crucial for running a clean burn. If that is kept below 20%, all will be well and the chimney will only sweep small amounts of soot and tar, otherwise there will be much larger falls of soot, and the fire will smell kippered, tarry and generally unhealthy, as if a garden bonfire has entered the house.

  13. p.g.sharrow says:

    The installation and use of wood fired heating is SELF DEFENSE against expensive and undependable electric power. Wood or Coal is dirty and difficult to use, a real pain to work with. This problem is the hallmark of Bureaucratic failure. A demonstration of government failure to provide for the better solution…pg

  14. BLACK PEARL says:

    I did read some time back that there were far more road particulates generated from tyre dust & brake pads than ever came out of the tail pipe of a modern diesel vehicle !
    So are those particulate filters fitted to diesels no use ????

    If this is the case, we appear to have been miss-sold diesel vehicles buy the EU ‘experts’
    Will there be compensation available if its going to cost the diesel vehicle owners extra expense, as is the case in the ongoing PPI claims ?
    Bit of a tricky one I guess, with the Scientists ‘say’, experts ‘say’ and politicians ‘say’… being wrong yet again.

  15. oldbrew says:

    ‘A vehicle might still pass the MoT visible smoke emissions test, which is primarily
    intended to identify vehicles that are in a very poor state of repair, whilst emitting
    illegal and harmful levels of fine exhaust particulate.’ – Government statement

    Diesel particulate filters

    Removing a diesel particulate filter is an automatic MoT fail.

  16. Sorry Oldbrew you are wrongly blaming diesel for NOx production. NOx is formed at high temperature Petrol burns (or is exploded by ignition) at a much higher temperature than diesel which self ignites under pressure. So petrol ignition causes more oxidation of the nitrogen in the air. Even higher temperature results from the combustion of natural gas or methane. On cold days the source of NOx is likely to be all those gas fired boilers Combustion of diesel and fuel oil give flames with high radiant heat (through high emissivity). Natural gas (unless throttled for air) gives very low emissivity. For the same radiant heat transfer the flame temperature needs to be several hundred degrees higher and this causes more NOx. Finally, NOx can be reduced by reducing conditions such as injection of fuel (coal or heavy fuel oil) into the combustion zone or just after where the high temperature is occurring but that can result in CO and unburnt particles. It should be pointed out that a diesel engine that emits some black smoke will produce no NOx.
    Diesel was promoted because it is very much more efficient than petrol and is cheaper to produce (straight distillation with less gas flaring from CAT Crackers). The Greens do not like any fossil fuel for political reasons so they are now out to kill diesel use. Do not fall for Green’s tricks and lies. High pressure critical water boilers with automated controlled low excess air combustion of pulverised coal is the best solution at present for power production.

  17. I should have added that wood burns at relatively low temperature and there is little or no NOx created by oxidation of nitrogen. However, wood does have combined NO radicles in the organic matrix and NOx can be produced by burning of the wood matrix. It is very difficult to control the combustion in a domestic wood burner so there will be some emission of particles, NOx, SOx., CO CO2, H2O, and CH4. However, if you live on some land with lots of trees, it is a free fuel, and will cause no concern if the chimney is high enough. I have a burner in the fireplace which gives a visual pleasure and warmth on a few cold nights of our mild winters. We have basaltic soil and can see trees grow several metres every year. More free wood than we can handle.

  18. Tim Hammond says:

    If you want real junk science, look no further than PMs. There is no biological mechanism (unsurprisingly since PMs include natural things such as pollen), the relative risks are paltry (usually 1.2), and all suffer from the exposure fallacy – many of the supposed “excess deaths” won’t actually have been exposed to the “pollution”.

    This is yet another scare story about nothing, with no actual evidence to support the claims if thousands of deaths.

  19. oldbrew says:

    Test data for diesel and petrol vehicles…

    The EQUA Air Quality Index is the independent authority on how car emissions affect air quality. Poor air quality is a serious issue in many locations, contributing to some health problems. All vehicles running on diesel or petrol/gasoline emit air polluting nitrogen oxides (NOx), but the amount varies significantly from car to car.

    The EQUA Air Quality Index clearly identifies vehicles emitting the lowest quantities of nitrogen oxides (NOx) on a scale from A (best) to H (worst).


  20. parliamentofideas says:

    Here in the Mid-Atlantic States of North Carolina and Virginia, we export wood pellets by the millions to the UK to burn for power production. Why? Because it is apparently illegal, or quite costly, to burn coal, oil or nuclear for power production.
    Pogo, “We have met the enemy and he is Us.”

  21. Robin Heath says:

    The enemy is vested interests posing as a caring democracy, underpinned by a bought priesthood of modern climate scientists, some of whom, it has been alleged, were corruptable because they needed a job. The person on the Clapham omnibus (this will do nicely as an example in London’s case) is hardly going to be responsible for the death of the world because they fit a wood stove and scrat around for free wood in order to keep their family warm, while ten million diesel vehicles charge around the city 24/7. But if and when ten million people, once driving those vehicles, follow suit because they can no longer afford to pay for the energy supplied by the oil and gas utilities, then surely our world would rapidly disappear in the form we have known it. The White Van Age will be over, fulfillment centres will become ruinous and Amazon will return to being just a large river in South America. And the air will become much cleaner.

  22. oldbrew says:

    BBC Viewpoint: The trouble with diesel

    The trouble is that diesels with particulate filters are much more common than they used to be, so how come the pollution is getting worse ‘due to diesels’?

  23. oldbrew says:

    Plan to reduce air pollution chokes in Mexico City
    February 2, 2017

    ‘Having fewer motorists on the road on Saturdays led to close to zero impact. Proponents of the Saturday program had estimated vehicle emissions would be reduced by 15% or more.’

    Read more at: http://phys.org/news/2017-02-air-pollution-mexico-city.html

  24. Oldbrew maybe you are beginning to realise that diesel is not the cause of NOx pollution. Mexico has lots of gas and I found on the internet that Mexico is amongst the world’s three largest users of LPG. In Australian capital cities all taxis use LPG as a fuel. LPG burns hotter than petrol and a conversion of older cars required the replacement of the valve stems in cylinder heads to withstand higher temperatures. For many years I drove company cars that had dual LPG/petrol with the LPG tnk tanking most of the boot space. Compressed natural gas (as used in trials for some city buses) is even worse. I say again oxygenation of nitrogen in combustion only occurs at high temperature.