A new study has revealed wood-burning and eco stoves release high concentrations of toxic pollutants that pose serious health risks.

The trendy home appliance is often used by households in the winter months to save money on their heating bills.

Many think that modern stoves which use advanced combustion technology offer a cleaner, safer alternative. 

But now experts warn that it can affect indoor air quality, causing potentially serious health implications.

These include chronic respiratory conditions, heart disease, lung cancer, and even damage to the kidneys, liver, brain and nervous system. 

This is because they release pollutants such as ultrafine particles (UFPs, fine particulate matter (PM2.5), black carbon (BC) and carbon monoxide.

It is estimated that 3.2 million people die prematurely each year globally due to household air pollution due to incomplete fuel combustion—including 237,000 children under the age of five.

Researchers monitored five homes in Guildford, Surrey, that used a range of heating stoves and clean solid fuels, including seasoned wood, kiln dried wood, wood briquette and smokeless coal.

A new study has revealed wood burning stoves can release harmful pollutants into your home

In first place with the highest emissions were open fireplaces, which increased PM2.5 exposure up to seven times more than modern stoves.

Then in second place were multifuel eco-design stoves, which emit more UFP emissions than standard eco-design models—which are top-rated for low emissions under a UK certification scheme.

Meanwhile wood briquettes and smokeless coal increased UFP exposure by 1.7 and 1.5 times respectively compared to modern stoves—challenging the assumption these manufactured fuels are cleaner.

While improved stoves reduced pollutant emission overall, the best models still caused significant spikes in indoor pollution during lighting, refuelling and ash removal.

Concerningly, they observed in many cases the pollutant levels exceeded those recommended by the World Health Organization (WHO). 

They also found ventilation is important with homes with closed windows during burning having up to three times higher pollution levels than those with them open. 

Smaller room size and longer burning durations were also associated with worsened indoor air quality. 

Lead author of the study, professor Prashant Kumar, said: ‘With rising energy prices many households will be turning to solid fuel when colder months hit, often assuming that modern stoves offer a cleaner, safer alternative.

In 2021, WHO revised their guidelines on the recommended safe air quality levels for pollutants

‘However, our findings show that this shift comes at the cost of indoor air quality, with potentially serious health implications considering people spend up to 90 per cent of their times indoors.

‘Public health advice, ventilation guidance, and building design standards must adapt to keep pace with these changing heating habits.

Abidemi Kuye, PhD researcher at the GCARE, added: ‘Even in homes using ‘cleaner’ stoves and fuels, we saw pollutant levels rise well beyond safe limits—especially when ventilation was poor or stoves were used for long periods. 

‘Many people simply don’t realise how much indoor air quality can deteriorate during routine stove use. 

‘This research shows the need for greater awareness and simple behavioural changes that can reduce exposure.’

The team at the University of Surrey’s Global Centre for Clean Air (GCARE) published their findings in Nature’s Scientific Reports.

Previously, experts had suggested the benefits of trendy burners such as improving mental health and bringing families together had been ‘overlooked’.

In a report at the start of the year, experts from the Stove Industry Association (SIA), the UK’s trade association for the industry, said stoves and fireplaces are good for physical and mental wellbeing.

The SIA didn’t contend the health dangers of pollutants emitted from stoves, but instead promoted the benefits.

They claim that wood burners bring families together and are cheaper and more ‘accessible’ than electric heating.