Emissions from wood combustion in Flanders have risen sharply – by more than 44% in 2022 (and even 140% compared with 2019). Yet, the Flemish government reports to Europe that the figures are falling by 16%. Due to inaccurate reporting and a flawed wood-burning stove policy, the health risks are underestimated.

Sales of wood and pellet stoves have been rising for years, but since the 2022 energy crisis, the trend has accelerated. A whopping 19,336 wood stoves were sold then, a 41.6 percent increase over 2021. In 2023, that number even rose to 20,702 stoves sold. That’s a whopping 140 percent increase compared to 2019.

Carcinogenic substance

As a result, the Flemish Environment Agency (Vlaamse MilieuMaatschappij, VMM) recorded a significant increase in concentrations of benzo(a)pyrene (BaP) in 2022: this is a harmful, carcinogenic substance that can be directly linked to wood combustion.

BaP concentrations are typically higher in winter, and wood burning is the main contributor during the building-heating season. In 2022, there was no further improvement in air quality, and the substances are strongly linked to increased wood burning.

Within households’ PM emissions, wood combustion accounts for about 85% (with other household fuels collectively accounting for about 4%). For total Flemish PM2.5 emissions, households are the largest sector (about 49%), “mainly due to heating with (wood) stoves.”

In 2022, benzo(a)pyrene emissions across all measuring points in Flanders had increased by 44%, according to VMM, due to increased wood combustion in people’s homes as a result of the energy crisis. However, Flanders does not report these figures to the European Union.

Significant drop in emissions?

Flanders uses a mathematical model and, strangely enough, concludes that – despite massive stove sales and rising benzo(a)pyrene concentrations in the air – emissions in Europe have fallen—a substantial drop, even, of 16%.

According to the Flemish government, emissions have even dropped further in 2023, the peak year for wood-burning stove sales. They have never been so low, according to the measurement model.

Discrepancy

The discrepancy, however, is alarming. It indicates that something is wrong with the calculation method and that it also appears not to be based on actual figures. For example, the Flemish government doesn’t know how many stoves there are in Flanders. Sales of these stoves have never been recorded.

In 2018, the government already promised improvements, but to this day, sales of wood and pellet stoves, along with stove types, ages, and energy efficiency, are not monitored. The sale of firewood is also not officially registered anywhere. Therefore, the emissions report cannot possibly be correct.

Missing link: cost of energy

However, Flanders has attempted to include the wood burned in its model, basing its calculations on a single key parameter: average daily temperature, reasoning that lower daily temperatures lead to more wood burning. And that immediately explains the discrepancy in the figures.

In other words, wood consumption may be much higher than assumed, and the emissions from the new stoves may have been underestimated, VMM concludes.

There is another element that increases the uncertainty of the results and, strangely enough, neither the VMM nor the emissions model has taken into account: the cost of the energy sources. When gas, electricity, or heating oil becomes very expensive, people will switch massively to wood, even in a warmer year.

And that’s exactly what happened in 2022: gas and electricity became exorbitantly expensive, and people flocked to wood and pellet stoves. But the Flemish calculation model doesn’t reflect this.

Erroneous results

In other words, “The emission values ​​are completely unrealistic, resulting in a far too optimistic assessment of the health risks,” says Geert Molenberghs, biostatistician, KU Leuven, UHasselt.

The Flemish Energy and Climate Agency (VEKA), which uses the same skewed model as the VMM to report the energy generated by wood-burning stoves to Europe, also publishes erroneous results.

For example, the sharp increase in sales of new stoves has reportedly yielded no energy gains whatsoever. On the contrary, according to the Flemish calculation model, those stoves produced 1% less green heat. (Burning wood is considered renewable energy in Europe, e.n.).

Conclusion?

Flanders has absolutely no wood-burning stove policy: no figures, flawed models, no incentive or guidance to replace old stoves, and no accurate measurement of emissions or energy consumption.

Barely anything remains of the famous 2018 Green Deal, which was supposed to green the Flemish stove market. Flanders leaves policy to Europe and takes almost no initiatives to control wood burning.

Elsewhere in the world

In Flanders and Western Europe, wood burning is often a space-heating and ambiance practice, not a daily cooking necessity. The health burden can therefore be very seasonal and local, while globally, the dominant driver of household combustion harms remains solid-fuel cooking/heating in low- and middle-income countries.

In the UK, the government is reportedly moving toward health warnings on new wood-burning stoves and fuels, reflecting growing concern that ‘cleaner’ stoves don’t eliminate health impacts, especially from existing appliances and real-world use.

Largest annual killer

In the US, a Science Advances (2026) study estimates that winter PM2.5 from residential wood combustion causes roughly ~8,600 premature deaths per year. Popular reporting highlights the same core message: wood burning may be the primary heat source for only a small share of homes, yet it can account for a large share of wintertime particle pollution in some contexts.

WHO reports that household air pollution from polluting fuels/technologies causes around 3.2 million deaths annually. This burden is global, ongoing, and heavily concentrated in regions where clean cooking and heating are not widely available.

Globally, household combustion (solid fuels) remains the largest annual killer (millions per year), compared with wildfire smoke, which is often reported in the hundreds of thousands per year.