PM 2.5 particles are the smallest particles and are in the air inside and outside of our homes whether we have a stove or not (think the finest of dust particles). It is these particles that are dangerous to health for everybody if prevalent in high enough numbers over long periods of time.
A wood burning stove, correctly working, will not exceed small particle safe-guidelines (I will provide some figures shortly) or come anywhere close. A stove sucks air from the room, drawing particles into the fire and off up the chimney and outside.
The conclusions of a US survey in 2019 by the Journal of Exposure Science and Environmental Epidemiology were that homes without stoves had a Median PM 2.5 of 6.65  µg/m3 whilst homes with stoves were a fraction higher at 7.98  µg/m3J. As a comparison outside air in central London averages 18-25  µg/m3.
Just think about that for a minute: a home has a natural and normal amount of 6.65  µg/m3 PM 2.5 particles all of the time, 24 hours a day (in my home it is usually around 7µg/m3 ). Using a wood stove can increase that a smidgen for the few hours the stove is on (whilst still remaining well within recommended safe guidelines).
So "very safe" becomes "still very safe".
With regard to clean air DEFRA states that their cleanest and freshest air classed is anything under 11  µg/m3. The World Health Organisation's advice is not to exceed annual average concentrations of PM 2.5 of 10  µg/m3n.
Note that this is an average over a whole year so even if your stove was running 24 hours a day, 365 days a year the average PM 2.5 levels would still be within WHO safe guidelines. For most homes, woodburners are only used for a few hours a day, a few months of the year and PM2.5 additions, caused by a stove, are negligible.
Scale by DEFRA. Sources at foot of page.
Highlighted figure is PM2.5 level - under 35 is low, under 11 is there absolute freshest on the DEFRA scale.
Scroll through the pictures to get the full story.
Experiment: I lit one match and let it burn almost to finger. I stood 2 metres from the meter.
Levels returned to "007" about 10 minutes later.
Wife gently cooked an omelette (did not burn it).
It took one hour and 13 minutes for the PM2.5 levels (caused by the wife cooking an omelette) to drop from 107 to 37
And another hour to drop from 37 to 19
Highlighted figure is PM2.5 level (under 35 is low, under 11 is the absolute freshest on the DEFRA scale).
Scroll through the pictures to get the full story.
Prior to lighting reading is 011.
Why did lighting a match not cause a significant raise as it did in the morning? Because I lit the match just inside the stove door and the draw of the chimney sucked away any smoke or smell from the match.
A couple of minutes after opening the door, prodding the logs to rearrange, and adding a new log.
Rest of evening settles around 008 to 010.
Recent press reports (late Dec 2020) discussed PM 2.5 pollution inside houses. These articles all stemmed from one syndicated article. The article is by Rohit Chakraborty of "The Live Forever Club" (https://liveforever.club/resources/rohit-chakraborty), using a sample of just 19 stove users) and this stated:
"The results showed the burners were usually lit for about four hours at a time... During those four hours, average particle levels rose to between 27 and 195 micrograms per cubic metre of air" (under 35 is low, under 11 is there absolute freshest on the DEFRA scale).
This data differs wildly from the US data and I can state that these outlandish levels are not comparable to levels in my own house or other people I know with wood stoves. Lighting the or refuelling the stove in my house makes almost no difference whatsoever to small particulate levels (open my stove door and air is sucked INTO the stove and off up the chimney - "sucks the slippers off grandma" as the old saying goes).
Cooking causes the meter to go up and this is to be expected: the cooking particles are not funnelled up a chimney. Toast caused the PM 2.5 level to shoot up to 92 and well-done sausages peaked at 218. So are we going to ban sausages? How about toasters?
One thing is worth mentioning. When the level does rise it takes quite a while (an hour or two) to fall, unless multiple windows are opening to allow through-air (so post-sausage cooking you will be breathing in very high levels of PM 2.5 for a few hours).
Around 2.5 million homes in the UK use solid fuel fire or stoves.
https://www.gov.uk/government/publications/air-quality-explaining-air-pollution/air-quality-explaining-air-pollution-at-a-glance
In 2022 all wood burning stoves sold in Europe must be from a new generation of extremely clean-burning Ecodesign models (look for the term Ecodesign). Particles (the pollution) will be reduced to a bare minimum. Older, more polluting models (usually cheap Chinese) will be banned.
Good news you might think and, for the stove industry working hard on these new models, an exciting new era. I visited a factory in Devon and was surprised at the amount of time and technology that went into testing their latest models.
At the same time as the stove industry was innovating, a few high-profile politicians realised that air pollution in cities was becoming a hot topic and one that needed some swift attention. London, where most of these politicians are based, has high levels of air pollution because so many people are so tightly-packed into a small area and road traffic is dense, slow-moving and constant.
So let's focus on London.
During the winter of 2018 and then again in 2019 the British media, prompted by Environment Secretary, Michael Gove and Mayor of London, Sadiq Kahn lashed out:
"Wood burning stoves to be banned", said the headlines, followed by an avalanche of articles about the perceived sins of the wood burning stove (a few years earlier wood stoves were feted as part of the march toward a renewables energy revolution).
Much of what was written in these outbursts turned out to be, at best, sensationalist and, at worst, highly inaccurate.
It was also aimed at the wrong target entirely (we shall come to this shortly).
Kudos to the Mayor of London - he did later come out in support of Ecodesign stoves: https://www.london.gov.uk/press-releases/mayoral/tackling-toxic-emissions-from-wood-burners although the good news is not what the press tends to promote so maybe you did not read about this.
In central London, in 2013, 62% of PM2.5 emissions were from road transport (exhaust fumes, disk brake wear, tyre wear). This from the Mayor of London's own report (PM2.5 emissions are the smaller particles that are of the most concern when it comes to pollution).
Source: https://www.london.gov.uk/sites/default/files/les_appendix_2_-_evidence_base_0.pdf
Okay - it is from 2013. But the 2020 forecast does not look much different.
Where does the burning of coal, wood and smokeless fuel fit within the above charts? It is within the D/C (domestic and commercial) Other Fuels (central London 2% in 2013, projected 1% 2020).
Take a look at the PM 2.5 emissions from domestic gas for 2013 (1% in 2013 projected 3% 2020).
Now look at the projected trends to 2050 from the same document
Woodburning and multifuel stoves are within one of those little Pantone coloured strips, lumped in with open fires (more about this in a moment).
Of course one can do anything with statistics. The above figures are average for the year. In summer months emissions from solid fuel heating will often be close to zero (helping the average). In winter, especially in the evenings, the figure will be higher:
"In summer months the amount of pollution caused by solid fuel burning can be very low, but in winter wood burning can contribute up to 10 per cent of local emissions in London". https://www.london.gov.uk/what-we-do/environment/pollution-and-air-quality/guidance-wood-burning-stoves-london
So at its worst 10%? Unfairly lumped in with modern wood-burning stoves, old and new, are open fires and it is these that are the biggest offenders when it comes to the PM emissions caused by home heating. In London, 69% of solid fuel installations are inefficient open-fires (40% for the UK as a whole). If anything is to be banned it should be open fires and not wood burning stoves.
A ten-year-old wood stove has 80% fewer PM emissions than an open fire and the new Ecodesign stoves are even better at 90%. The politicians and media should have focused on open fires which account for 69% of solid fuel fires in London.
That headline that said "Wood Burning Stoves to be Banned" should have stated, "Open Fires to be Banned". But one cannot ban open fires because they are already built into the houses. Nobody is going to storm in and destroy them. So they attacked an easier target - wood burning stoves, the product that is 80-90% cleaner burning and the product that makes up just 31% of the London market. The people who replaced their open fires with wood burning stoves are the one the government and the media should be saluting.
Did you know that in London and many of our cities it is illegal to burn wood on an open fire? The problem is that politicians have not enforced this and the media have never shown an interest. Perhaps it is easier for them to attack something else in order to divert attention from their lack of action?
Oh... those articles about comparing stoves to trucks. Much of that is not correct and I'll be updating that here asap.
Are older wood burning stoves to be banned? Not if already installed. After 2020 new models will have to confirm to Ecodesign standards. And so they should. Every open fire upgraded to a new Ecodesign stove will reduce particle emissions by up to 90%. Technology moves on and if it exists and we can make the world a better place then so we should.
EcoDesign arrives in 2022 and is promoted by the government as the next generation of clean wood stoves.
As 2022 approaches more and more press releases shall be released by the government (and presumably more rubbish from the media will be spouted).
The government, very reasonably, want to reduce the following:
They want customers to purchase the latest Ecodesign-Ready stoves and want users to burn dry wood only. This is completely in line with stove-industry desires.
Let's continue the good work. Say no to open fires. Ecodesign is the way forward.
Let's not forget that almost everything causes some weight to be added to the "negative" side of the scale when it comes to the environment. Solar panels? Wind turbines? All need manufacturing and servicing and all have a carbon footprint. Car, rather than bicycle? Tyres need changing at some time. Not to mention plastics, airports and so on.
Coal and gas are not renewable resources. Electricity is not when it comes from a coal-powered power plant.
Wood is a renewable resource. A tree absorbs carbon when it is growing and emits it when burned or rots on the ground. Carbon neutral.
25 May 2019: Please note that this article will remain "work in progress" whilst I continue to investigate the subject thoroughly. It is a hard slog reading all the articles but difficult to interpret the results and remove bias. If anybody can assist me to improve this article feel free: info@stovefitterswarehouse.co.uk
Poor behaviour of politicians and media risks damaging an industry that can play a valuable role in the renewable energy market, a market that I feel passionate about. My wife and I have an Ecodesign wood burning stove and, because of this, we never use the gas central heating. We have a well-insulated property and just a few logs, on cold evenings, keep our open-plan property warm and cosy. The smoke from our chimney is generally invisible, so clean and hot is the burn.
Julian Patrick is the author of The Stovefitter's Manual and an experienced wood burning stove installer (including solid fuel heating systems).
Laid down tools in 2013 to write The Stove Fitter's Manual and open a small shop in North Wales (the Wood Stove Hut). Launched Stovefitter's Warehouse soon after due to fast growth of sales.
Own stove is a DG Ivar 5.
Already have a chimney? You need 1. Stove 2. Liner 3. Fitting Pack 4. Chimney closure plate (Hardiebacker board from Builder's merchants or galvanised sheet).That's it!
No chimney? Check out our shed kits or let us design your clip-together chimney design - easy peasy.
Stovefitter's Warehouse is owned and managed by Julian Patrick, blogger and author of The Stove Fitter's Manual. Julian was previously a full-time installer of wood-burning stoves (including solid fuel heating systems). He laid down the tools in 2013 to write his stove manual and open a small shop in North Wales (the Wood Stove Hut, soon to grow into The Stovefitter's Warehouse).
