A crackling fire in a wood stove may sound like a very ecological and healthy way to warm up our homes, but is that true? A new study shows domestic heating from wood and other kinds of biomass is a major source of toxic air pollution, Roberta Arbinolo reports.

As the World Health Organisation (WHO) gears up to launch new Global Air Quality Guidelines and calls for concerted action to protect people from dangerous air pollutants, the European Environmental Bureau (EEB) and Green Transition Denmark draw attention to the impacts of domestic heating emissions and the EU role to curtail them.

Where there’s fire, there’s smoke

Domestic heating with wood and coal in small private stoves and boilers emits about half of all fine particulate matter (PM2.5) and black carbon within the European Union. Besides, domestic wood burning is also an important source of even smaller ultrafine particulate matter (PM0.1). This is some of the evidence gathered by the EEB and Green Transition Denmark in a new study which compares the air pollution, health and climate costs of a range of fuels that can be used to keep our houses warm.

PM2.5 is one of the most dangerous forms of air pollution: these minuscule solid particles – less than 2.5 micrometres in diameter – can penetrate deep into the human respiratory tract and enter the bloodstream, causing lung and heart diseases as well as cancer, influencing the central nervous system, and affecting reproductive organs.

Furthermore, domestic heating with wood emits relatively high concentrations of dioxins, very persistent and toxic chemicals that accumulate in the food chain and can cause reproductive and developmental problems, damage the immune system and interfere with hormones.

Biomass-powered stoves and boilers can also significantly contribute to indoor air pollution, since they are placed inside our homes and can leak pollution directly to indoor air in seasons with limited ventilation.

Emissions from heat sources vary considerably depending on a range of factors which include the age and size of the plant, stove or boiler, and the geographical location, as well as the quality of the fuel and how it is managed. However, the new study shows that wood, coal and straw burnt in small stoves and boilers are the most polluting and health damaging heat sources, with the highest associated cost in terms of mortality and morbidity.

Under-regulated

Despite their severe impacts on air pollution and human health, domestic heating emissions are under-regulated in the EU, especially when compared to other sources such as traffic. Neither the EU EcoDesign requirements nor the more ambitious Nordic ecolabel succeed to keep particle emissions from new stoves within acceptable levels. In 2022 a new EcoDesign stove will be allowed to emit 60 times as much particulate matter as an old truck from 2006, and 750 times as much as a newer truck from 2014.

When it comes to ultrafine particulate matter, a test run within the study showed that the smoke of a wood stove with the Nordic Swan ecolabel running under optimal conditions contained at least 2,000 times more particles than the exhaust of a truck with particulate a filter.

Looking ahead, the EEB and Green Transition Denmark warn that the relative share of polluting and climate-wrecking emissions from domestic heating is set to increase, as the sector is not regulated as strictly as other emission sources.

Kare Press-Kristensen, Senior advisor for Air Quality and Climate at Green Transition Denmark, told META:

“It is high time our governments and the EU took domestic heating pollution seriously. We need stricter emission limits for wood stoves and boilers, and a Europe-wide campaign to promote better insulation and truly clean heat generated from heat pumps.”

New guidelines in the air

The study sheds a light on the air pollution and health costs of domestic heating from wood in a key moment for the European and global air quality debate: on 22 September 2021, the WHO will publish new Global Air Quality Guidelines that are meant to guide legislation and policies to curb air pollution and decrease the burden of disease that results from exposure to toxic air worldwide.

The current guidelines date back to 2005, and are now being updated to reflect the latest scientific evidence of the damage air pollution inflicts on human health, as well as to recommend stricter reduction targets for key air pollutants, some of which also contribute to climate breakdown.

A recent analysis by the Centre for Research on Energy and Clean Air (CREA) shows that current air pollutant levels in many countries are far above WHO 2005 guidelines, and air quality standards are too weak, especially when it comes to PM2.5 – one of the most dangerous forms of air pollution. However, even if all countries met the 2005 guidelines, air pollution would still be responsible for around 5.5 million deaths every year, CREA reports.

Emilia Samuelsson, Policy Officer for Air Quality and Noise at the EEB, told META:

“Scientific evidence is increasingly clear: there is no safe level of air pollution. Yet our governments are not even following WHO recommendations set 16 years ago. What are they waiting for, to cut air pollution from all sectors, including domestic heating? Their delay is costing us our health and a safe environment.”

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