As fossil fuels are phased out, biomass such as firewood, wood chips and branches is increasingly being used to heat homes in EU countries.
But as more forest is burned, researchers warn that small particles formed during combustion can spread far and wide, penetrate the body and harm human health. In addition to the risk of premature death, there is a risk of cardiovascular disease, asthma and cancer.
The report also shows that Europe has lost 11 percent of its tree cover in 25 years.
