Wood Burning Frequently Asked Questions

The London Wood Burning Project (LWBP) is jointly led by the London Boroughs of Camden and Islington on behalf of 18 other London boroughs. Our aim is to raise awareness of the public health impacts of wood and other solid fuel burning in stoves and fireplaces in London, which has been growing in popularity and represents an increasing source of air pollution.

We conducted surveys of over 5,000 London residents during the winters of 2022/2023 and 2023/24 to better understand public attitudes and behaviours around wood burning.

We commissioned independent experts to conduct and publish air pollution measurement at the household, neighbourhood and city level. We engaged independent experts to conduct health impact evaluation modelling, quantifying and monetising the health impacts of domestic solid fuel burning in each of the member boroughs and across London as a whole.

The project team, including all participating boroughs, completed an awareness campaign during winter 2023/2024. This campaign shared impactful messages about the public health impacts associated with domestic wood burning via billboards, radio, posters in health and council locations, bus rears, digital and social media advertising. The campaign was founded on scientifically robust evidence pointing to how domestic wood and solid fuel burning produces air pollution with an associated risk for public health.

Wood burning emits particles known as particulate matter (PM). These particles are of different sizes, and the smaller the particle, the further they can travel into the body. These particles, once inhaled, can lodge in the lungs or travel throughout the body in the bloodstream to settle in arteries or organs, and the smallest can cross into the brain.

The ability of particulate matter to travel throughout the body leads to its role as a causal or contributing factor in:

• Neurological disorders including dementia
• Diabetes
• Lung disease including lung cancer
• Heart disease
• Stroke
• Asthma
• Infertility

Domestic wood burning is estimated to contribute 17% of London’s PM2.5 emissions and is the second largest source of PM2.5 emissions in London, after road transport. There is comprehensive evidence of the health harms of particulate pollution in virtually all parts of the body. Poor air quality is the largest environmental risk to public health in the UK. There is research being undertaken to find out if particulate pollution from different sources has different impacts on human health and we are eagerly awaiting the results.

The Clean Air Act prohibits the release of smoke from chimneys in ‘smoke control areas’. However, emissions data and our own research has shown that all types of wood burning appliances produce health-damaging particulate matter that contributes to outdoor air pollution, even if visible smoke is not present. In this way, the current laws do not fully protect public health from air pollution from wood and solid fuel burning.

Our primary objective is to encourage people to think about the personal and community health risks associated with air pollution and to reduce or stop burning wood at home if they have an alternative source of heating. The next steps for the project will be to further improve environmental education in London and to support local authorities to enforce the Clean Air Act.

Yes, all solid fuel burning appliances release pollutants, including particulates, through their chimneys when in operation. The level of pollution emitted will be dependent on several factors including installation, maintenance and operation of the appliance, and the choice of fuel. If wood smoke can be smelt outdoors, particulate pollution is being emitted from the chimney and this will be contributing to the air pollution in London.

Yes, all solid fuel burning appliances release pollutants, including particulates, through their chimneys. In many cases harmful pollution can also be released into the home during use or when refuelling. While it is true that the most recent generation of wood burning stoves are designed to produce less smoke, they are still producing polluting gases and far more particulate matter air pollution than gas boilers or electric heating.

Our survey found that people are more likely to use a wood burning stove more frequently than an open fireplace, so even if newer stoves do have comparatively lower emissions the increased usage may negate benefits for air quality.

Buying wood or other solid fuels will usually work out more expensive than using a gas boiler or air source heat pump. In 2023 Global Action Plan conducted an in-depth investigation into the costs of different heating configurations and found that a gas boiler was the cheapest form of heating that they modelled.  The Nottingham Energy Partnership publishes a monthly table of the costs per kilowatt hour (kWh) of different fuels. This shows that mains gas, or an air source heat pump are usually cheaper than kiln dried logs, wood pellets, or smokeless fuels.

The only way that burning wood could save money is by burning free wood. However, in a smoke control area wood must first be dried (seasoned) according to stove manufacturer specifications, and in any case can only be burned in a Defra exempt stove.

Free wood cannot be used as fuel in a fireplace or non-exempt wood burning stove. Burning waste wood may be toxic and illegal due to the presence of paint, varnish or treatment chemicals, and you are never allowed to burn household or garden waste in a fireplace or wood burning stove.

Your neighbour may not know about the harmful impact of their wood burning. If you know your neighbour you may feel comfortable discussing this directly with them, or alternatively raising this as a topic in a local social media or chat group. We have published some information that may help this conversation, read about it here.

If there is smoke coming from their chimney, and you live in a smoke control area you can contact your local authority, and they will be able to contact your neighbour and ensure that they comply with the Clean Air Act. If you don’t live in a smoke control area, you can ask your council to increase the current smoke control areas to include your neighbourhood.

Since the invention of the chimney, indoor fires have worked by drawing air from the room into the hearth, using the oxygen in the air to burn the wood, and having the resulting smoke and particles rise up the chimney and spread outside. This drawing of air is one of the reasons that fires must only be used in well-ventilated rooms as the air drawn up the chimney must be replenished, through open windows, air vents, or even gaps under doors and between floorboards.

Conventional open fireplaces are very inefficient, and a large amount of the heat generated by burning is lost up the chimney. Wood burning stoves were invented in the 16^th century but did not become popular until during the Industrial Revolution.  These stoves had a significant advantage in terms of the heat they produced for the quantity of fuel used, but open fireplaces were nevertheless still popular in many locations. Some of these stoves would often have been used for cooking and heating, and others exclusively for heating, but all would have still lost a lot of heat up the chimney, even though this was now a metal flue that may or may not be inside a traditional brick or stone chimney.

There has been considerable progress made in wood stove design and efficiency over the last few centuries, but they are still a significant source of particulate air pollution. An open fire typically emits about 2,950 grams of small particulate matter (PM2.5) per megawatt hour (MWh) of energy, a standard wood burning stove about 2,660 grams of PM2.5 per MWh, and the most modern EcoDesign wood burning stoves emit about 216 g/MWh. In contrast, a gas boiler emits about 0.72 g/MWh.

Yes, if you can smell wood smoke you are breathing in pollution resulting from wood burning.

A lot will depend on the reasons for burning wood. In our most recent survey 90% of respondents had a gas boiler, storage heater or heat pump. These are all good sources of heating, widely used within London. There is a large variation in housing in London, with mains electricity, gas or both available to households. The Energy Saving Trust can help individual households choose the best heating solution and give advice on access to financial assistance for some heating installations and upgrades.

The London Wood Burning Project is working to address the common myths around wood burning. We are trying to raise awareness that wood burning in urban areas produces avoidable air pollution, thereby contributing to the poor air quality that affects the health of urban communities – including people who do not burn wood themselves.

We also want to raise awareness that wood burning usually costs more than other heating sources since most people in London do not have their own supply of wood, and that as a heating source it is neither sustainable nor environmentally friendly because a large quantity of the wood fuel used in the UK is imported from overseas, with serious concerns about forest management and impacts upon biodiversity.

Ultimately, we all need to take action to safeguard our health by improving air quality for ourselves and our community, and to tackle the climate crisis which is already having an impact upon London. This includes making sustainable choices for our home heating, wherever we can do so, and in London and many other urban areas this means reducing the use of wood and other solid fuels. Limiting avoidable air pollution from home wood burning will be better for climate and will help to improve air quality, leading to better health outcomes for everyone who lives, works and travels in London.

Domestic wood burning is estimated to contribute 17% of London’s PM2.5 emissions and is the second largest source of PM2.5 emissions in London, after road transport. A significant quantity of wood fuel used in the UK is imported, and this should not be considered as a ‘carbon neutral’ fuel. Additionally, the length of time taken for carbon to be re-absorbed in replacement trees means that burning wood for domestic heating is not compatible with efforts to tackle the climate crisis.

The harm is to people as well as the environment.  Air pollution is a risk factor in the top five leading causes of death in England and Wales in 2022. As a result, it is attributed as the cause of as many as 36,000 premature deaths each year in the UK – including more than 4,000 in London. Some estimates place the annual cost of air pollution to the NHS and the economy at £20 billion per year. Anything that increases air pollution increases individual and population risk of developing one or more health conditions linked to pollution exposure. The air pollution from domestic wood burning is spread across the city, beyond those using stoves and fireplaces, and can have the greatest impact on some of the most vulnerable individuals.

Wood burning stoves are marketed as clean, low-cost, and carbon neutral and many people are drawn to the aesthetic appeal of a cosy fire. There is little information distributed about the health risks associated with the air pollution that is produced by even the most modern wood burners.

Additionally, important messages about the climate impact of wood burning are not being conveyed. Our survey found that in London ‘creating a nice atmosphere’ was a popular reason given by regular users of both open fires and wood burning stoves. Aesthetic reasons for using solid fuels may be common in cities like London where mains gas is readily available, and most homes already have gas or electric heating installed. In rural areas where mains gas is not available, and even electricity networks may be subject to outages, the reasons for installing a wood burner will be different.

All animals, whether pets, wild animals, or zoo animals can suffer from the health impacts of particulate pollution. Birds may be particularly vulnerable to air pollution due to the increased efficiency of their respiratory systems. Even though fish don’t breathe air, they may consume particulate matter that settles on the water and many of these particles can be toxic to the fish.