Air pollution from wood-burning stoves linked to dangerous sleep condition that sends heart attack risk soaring, in disturbing new research

A new study has found that high levels of air pollution can exacerbate the symptoms of a dangerous sleep condition linked to an increased risk of heart attacks. 

Obstructive sleep apneoa (OSA) causes people to repeatedly stop breathing—for a few seconds or more than a minute—when the muscles which support the tongue and soft palate temporarily relax and the airway becomes blocked.

Symptoms include loud snoring, making gasping, snorting or choking sounds, and waking up frequently in the night. 

In the day, it can indirectly cause fatigue, concentration difficulties, mood swings, and a headache upon waking.  

The Sleep Apnoea trust estimates that up to 10 million people in the UK could have some form of OSA, with obesity a major factor in the development of the condition.

However, a new study has linked the condition—which has also been cited as a cause for weight gain and linked to an increased risk of heart disease and stroke—with the presence of a form of air pollution called PM 10.  

PM 10 are tiny particles released by vehicle exhausts, industrial processes and the burning of solid fuels, as used in wood-burning stoves.

Yesterday we reported that researchers found that the emissions from wood-burning stoves can damage the lungs in a similar way to cigarette smoke. 

For this new study, Italian researchers looked at 19,325 patients with OSA from 14 countries and levels of PM10. 

They found every unit of the pollutant caused an increase in the subjects’ apnoea hypopnea index (AHI). 

AHI measures how many complete breathing pauses (apneas) and partial breathing reductions (hypopneas) happen per hour of sleep—and the higher the number, the more severe the case of OSA.

If a patient had an AHI that was low—less than five—this correlated to the average level of PM 10 where they lived. It was also relatively low, approximately 16 µg/m³.

Meanwhile, if a patient had a high AHI—measured as five or more—the average PM 10 where they lived was higher, around 19 µg/m³

Previously PM10 has been linked to high blood pressure, heart attacks, strokes and even early death.

On their findings, Professor Martino Pengo, from the University of Bicocca who presented the research said: ‘Even after we took account for other factors that we know have an effect on OSA, we still found an average increase in the number of respiratory events per hour of sleep of 0.41 for every one unit increase in PM10.

‘This effect may seem small for an individual, but across entire populations it can shift many people into higher-severity categories, making it meaningful from a public health perspective.’

Interestingly they also found differences between strength of the link in different cities. It was particularly strong in Lisbon, Paris and Athens.

‘These regional differences may be due to things like local climate, the type of pollution or even how healthcare systems detect OSA,’ explained Professor Pengo. 

In the future the team hope to find out why the effects vary between different cities and if some people are more affected by pollution than others. 

They also hope to explore if they can improve sleep apnoea symptoms by reducing pollution. 

Professor Sophia Schiza, head of the European Respiratory Society’ expert group on disordered breathing, added: ‘For people with OSA, especially those living in cities with high levels of air pollution, this study is important as it suggests pollution could be making their condition worse.

‘For doctors caring for people with OSA, this research highlights the need to consider environmental factors like air quality alongside other risk factors.

‘This study strengthens the connection between environmental health and sleep medicine,’ continued Professor Schiza, who was not involved in the study.

‘It reminds us that tackling air pollution isn’t just good for the planet, it’s also vital for our lungs and our sleep quality too.’

In February 2024, data released by Defra revealed that wood burning at home is producing producing 22 per cent of the most harmful type of particulate matter pollution versus 18 per cent for roads.

Particulates are fine invisible particles measured in two units—PM2.5, smaller particles which measure 2.5 micrometres, and larger particles, PM10, which are 10 micrometres.

A typical human hair is around 70 micrometres wide, 30 times bigger than a fine particle.

The report said that for 2022: ‘Emissions of both PM10 and PM2.5 from domestic combustion have increased by 19 per cent between 2012 and 2022, which reflects the greater popularity of domestic solid fuel appliances like wood-burning stoves.’

Wood-burning stoves are popular in homes across the UK, but new research found that their sooty emissions can damage lungs in a similar way to cigarette smoke.

The findings presented at the European Respiratory Society Congress in Amsterdam showed those who used them lost lung capacity more quickly that non-smokers.

Dr Laura Horsfall, Principal Research Fellow at University College London, who led the study, said: ‘Our study suggests that high levels of particulate matter from stoves damage respiratory tissues, causing inflammation in a similar way to cigarette smoke.’

She added: ‘We know wood burning at home emits harmful air pollution both indoors and outdoors including known carcinogens.

‘Despite this, air pollution from this source has approximately doubled in the UK since 2009 as more people install and use wood stoves.

The findings suggest that the fashion for wood-burning stoves, often marketed as environmentally friendly, could be driving a hidden health problem.