Are wood burning stoves bad for indoor air quality?

No, not particularly. It's all relative in our view, but let us explain. There have been some newspaper articles which seem to have got everyone in a bit of a panic on this subject, most recently those covering research entitled ‘Indoor air pollution from residential stoves’ which was carried out by Sheffield and Nottingham universities. However, it is important to remember that there are many other things that also affect the quality of our indoor air such as cooking with gas, lighting candles, using aerosols and simply vacuuming and dusting – plus a host of other essential activities that we barely give a second thought to and which can be much worse. So let's try to get things in perspective by examining some of the facts.

Government guidelines suggest that an indoor air pollutant reading below 35ug/m3 is considered low and that anything above 72ug/m3 is 'very high'. Incidentally, 1ug/m3 is equal to one-millionth of a gram for every cubic metre of air. In 2016 respected consumer journalist Harry Wallop was already beginning to examine some of the misconceptions regarding stoves and indoor air quality and wrote a couple of articles for the Daily Telegraph and the Times which were supported with data he'd collected himself at home. Firstly, he discovered that under normal circumstances his house had a steady reading of between 18ug/m3 and 22ug/m3 – proof that our homes are generally full of more dust, pollutants and particle matter than we'd ever like to think, but certainly well below the government's 35ug/m3. When it came to operating his stove, and his was an old stove and not one of the latest low emissions Ecodesgn stoves, its steady reading was just 42ug/m3. Interestingly, when he accidentally burnt his toast, the reading spiked at a staggering 10,000ug/m3 and even after an hour the reading was still sitting at around 300ug/m3.

The graph shown below, which is part of detailed research carried out by British stove maker, Burley Appliances, clearly indicates that there are much worse offenders in our homes when it comes to indoor air quality – including birthday cake candles. Full details of how the data for the graph was gathered, plus an excellent critique of Sheffield and Nottingham universities' research, can be found at www.burley.co.uk/technical-introduction/. Our friends at Stovax have also produced their own graph with similar results, which is also shown below. Note the spike for roast dinner.

This, and other matters, gives rise to a number of issues regarding the Sheffield and Nottingham universities research. Firstly, the authors seem to us to have a lack of basic understanding about how stoves work. In addition, a number of conclusions have been made which are simply not supported by the evidence provided. The report itself indicates that the air quality monitors used in the research were of low-cost and were not calibrated so that realistically any data collected has to be of questionable accuracy and therefore the conclusions based upon it must be uncertain. As we've stated already there are many other factors which influence the quality of our indoor air and these do not seem to have been fully considered, for example cooking and smoking. There is no mention of the ventilation status of the rooms the stoves were housed in. Building regulations require a specified number of air changes per hour in habitable rooms as well as a sufficient air supply to allow the stove to safely operate – both of which will have a dramatic affect on the safe performance of the stove and the room air quality.

The Sheffield and Nottingham authors have stated that they are looking for funding to produce further research and should they be fortunate to get it then let's hope that the issues and concerns that the stove industry has identified with the original research are addressed. Believe it or not, at The Stove Yard we hope that they are successful because the more information homeowners have on this subject then the better informed their lifestyle decisions can be. In the meantime the Stove Industry Alliance (SIA), which represents most of the stove brands available in the UK and Ireland are also funding independent research into this important subject with their report expected at the end of 2021.

There are many every day activities that are unavoidable or that we choose to undertake that to some extent pose risks to us; most of the risks are very, very minor so we don't even think about them and some risks are more calculated. Crossing the road or getting on to an aeroplane would be two good examples. However, we choose not to let such risks prevent us from enjoying safe, happy and normal lives. We must not forget that stoves not only provide homeowners with cheap abundant heat but also many other benefits that any stove owner will be all too happy to tell you about. So as we said at the start, let's get things in perspective.

Special thanks to Hetas, Nic Snell at Certainly Wood, Michael Coke at Stovax, the Stove Industry Alliance and in particular Burley Appliances for providing some of the background information to enable us to write this answer.