Exposure to household air pollution from using wood or coal for cooking and heating is associated with higher risk of death from heart attack and stroke, according to a study from Oxford University and researchers in China.
The study, published in the Journal of the American Medical Association this week, looked at the association of long-term use of solid fuels for cooking and heating with the risk of death from cardiovascular disease in around 271,000 residents in five rural areas in China.
Researchers from the University of Oxford, Huazhong University of Science and Technology, the Chinese Academy of Medical Sciences, and Peking University in China contributed to the study.
According to the research team, around three billion people worldwide use solid fuels (e.g. coal, wood, charcoal and crop wastes) to cook and to heat their homes. When burnt, these fuels produce smoke that contains fine particles – PM2.5 – and other substances, especially in houses without adequate ventilation.
It is estimated that worldwide about 2.5 million deaths in 2016 were related to the resulting household air pollution.
This study is based on the China Kadoorie Biobank prospective study of 0.5 million adults from five urban and five rural areas, which was established jointly by the University of Oxford and Chinese Academy of Medical Sciences during 2004-08.
During this time over 5,500 participants died of cardiovascular disease (either a stroke, heart attack or other condition) among those who had no history of cardiovascular disease at the initial recruitment.
The researchers found that, compared with people who mainly used gas or electricity, those who regularly cooked using coal or wood had a 20% higher mortality risk from cardiovascular disease, and people who heated their homes using solid fuels had a 29% increase in risk, after taking account of the effects of age, sex, socio-economic status, smoking, alcohol drinking, diet, physical activity, and weight.
The study also showed that the longer people used solid fuels, the higher the risk of death, the researchers claimed.
Study author, Professor Zhengming Chen, from the University of Oxford, UK, the co-lead Principal Investigator of the China Kadoorie Biobank, said: “Air pollution has caused a lot of concern in China, but people have been focusing mainly on the outdoor air quality and overlooking the health consequences of pollution arising from domestic burning of coal and wood for cooking and heating, which may have a more profound impact on health.”
The study also indicated that switching from solid to clean fuels for cooking reduced the risk of cardiovascular death by 17% and switching from solid to clean fuels for heating reduced the risk by 43%, the authors claimed.
Individuals who cooked on stoves using solid fuels but had proper ventilation had an 11% lower risk, compared with those whose cookstoves were not properly ventilated, the study suggests.
Professor Tangchun Wu, from Huazhong University of Science and Technology, China, said: “These findings are important because even though people might have been using solid fuels for a long time, there are still clear health benefits in switching to cleaner fuels. Installing ventilation facilities will be a cheaper and effective alternative for those who cannot switch to clean fuels.”