Action needed to cut emissions from domestic solid-fuel burning

Photo: Counselman Collection/ CC BY-SA

Air pollutant emissions from residential heating with solid fuels (wood and coal) are estimated to cause 61,000 annual premature deaths in Europe.

Small-scale domestic heating with wood and other biomass is popular in many countries in Europe and North America. Heating your home with wood is often actively encouraged and biomass is being touted as a renewable fuel that can assist with climate change mitigation and contribute to energy security.

The health impacts of wood and coal burning for residential heating, as well as policy options to reduce domestic emissions, are the focus of a thematic report by the Joint Task Force on the Health Aspects of Air Pollution, which is a joint body of the World Health Organization European Centre for Environment and Health and the Executive Body for the Convention on Long-range Transboundary Air Pollution.

In many places household wood combustion for heating is increasing as a result of government incentives, increasing costs of other energy sources and the public perception that it is a green option. Small-scale wood combustion can emit high levels of particulate matter (PM2.5 and PM10) and volatile organic compounds (VOCs). Wood smoke is also rich in black carbon – biomass fuels combusted for household heating and cooking contribute an estimated 34–46 per cent of total global black carbon emissions.

If current trends continue, emissions from household heating are expected to keep on increasing, due to climate policies (with biomass being considered a renewable fuel), the potential for economic hardships to increase dependence on solid fuels, slow adoption of state-of-the-art technologies, and the lack of strong incentives to exchange the current inefficient stoves and boilers in use.

According to the report, short-term exposure to particles from wood combustion is as harmful to health as particles from the combustion of fossil fuels. Hundreds of epidemiological time-series studies, conducted in different climates and populations, link daily increases in outdoor PM concentration with increased mortality and hospitalizations.

In 2010 an estimated 61,000 premature deaths in Europe were caused by outdoor PM2.5 pollution originating from residential heating with solid fuels (wood and coal), about the same number as in 1990. Outdoor air pollution from household heating with solid fuels also caused 1 million disability-adjusted life years (DALYs) across Europe in 2010. (See table.)

Table. Residential heating contribution to outdoor PM2.5 and burden of disease.

  PM2.5 from residential heating (%) PM2.5 from residential heating (μg/m3 Premature deaths, per year  Disability-adjusted life years (DALYs), per year
Selected regions 1990 2010 1990 2010 1990 2010 1990 2010
Central Europe 11.1     21.1 3.5  3.4  18,000 20,000  370,000  340,000

Eastern Europe 

9.6 13.1  2.0 1.4  24,000  21,000 480,000  410,000
Western Europe    5.4 11.8  1.3  1.7 17,000 20,000  280,000 290,000
High-income North America      4.6  8.3  0.9 1.1 7500  9200  140,000   160,000
Central Asia 9.9  8.3  2.4 1.6 5500 4200  180,000   110,000
Global 3.0 3.1 0.9  0.7  120,000   110,000   2,800,000  2,200,000

Globally, Europe has the highest percentages of outdoor PM2.5 concentrations attributable to household heating with solid fuels, with 12 per cent in Western Europe, 21 per cent in Central Europe and 13 per cent in Eastern Europe in 2010. In comparison, 8 per cent of the total ambient PM2.5 in Canada and the United States comes from household heating with solid fuels.

In the EU, specific regulations are being developed under the Ecodesign Directive for addressing the energy efficiency of and emissions from solid-fuel space heaters and solid-fuel boilers, particularly those that use various forms of woody biomass fuel (wood logs, pellets and biomass bricks). Some European countries (e.g. Austria, Denmark, Germany, Norway and Sweden) have issued national emission standards for small residential heating installations. The most comprehensive regulation is a German law from 2010.

Canada introduced new standards for new wood-burning appliances in 2010. In 1988 the United States introduced a new source performance standard (NSPS) for residential wood stoves, which is expected to be updated to a level equivalent to the more recent Canadian CSA standard.

It is noted that virtually all of these existing standards cover only new installations, and that they usually also are limited in scope – the Canadian standard and the NSPS, for example, cover only wood-stoves, but not fireplaces, masonry heaters, pellet stoves, indoor and outdoor wood boilers, furnaces and heaters.

As residential solid-fuel combustion for heating is likely to persist in many parts of the world in the near-term future, the report presents a list of recommendations regarding biomass and other solid fuel use for heating and energy production, summarised below:

  • Any renewable energy or climate change-related policies that support wood combustion should consider air pollution impacts and promote only the use of lowest emission or best available combustion technologies.
  • Introduce legal regulations for improved efficiency of new heating appliances. These regulations should include tight limits for the primary emissions of PM, gaseous hydrocarbons and carbon monoxide in particular.
  • Prepare heater exchange regulations or voluntary programmes. This type of action will be most successful if financial compensation is offered to incentivize the replacement of old heaters with those meeting tight energy efficiency and emission limit regulations.
  • Define urban areas with dense populations or special geographical features where residential heating by solid fuels (wood, coal) is not permitted at all or is at least limited to registered models of low-emission wood combustion devices. Coal burning in small-scale appliances should be permanently prohibited, at least in communities of developed countries.
  • Introduce regulatory use of “no wood burning” days or morning and evening hours during unfavourable meteorological conditions in vulnerable, densely populated areas and more generally in valleys of mountainous areas.
  • Implement community-wide information campaigns to inform the residents about the climate and health benefits of locally emission-free alternatives for house heating (e.g., district heating by well-controlled combined heat and power plants, geothermal energy for single houses or as a larger local installation, and heat pumps for single houses or apartments). Distribute information on how to properly dry and store wood logs and how to properly use current small-scale heaters.

Christer Ågren

Residential heating with wood and coal: health impacts and policy options in Europe and North America. ECE/EB.AIR/2014/6. By the Joint Task Force on the Health Aspects of Air Pollution. 26 September 2014. Can be downloaded at:

In this issue