New research published in PLOS Medicine looks at the risk of lung disease among Chinese villagers and finds that improving cooking fuels and kitchen ventilation may boost lung function and reduce chronic obstructive pulmonary disease.
Yesterday, Medical News Today reported on a new study by the World Health Organization (WHO), which found that, globally, 4.3 million deaths each year are as a result of indoor air pollution from cooking over coal, wood and biomass stoves.
This statistic has contributed to WHO declaring that air pollution is now "the world's largest single environmental health risk."
Wood, charcoal, agricultural residues and animal dung are widely used as cooking fuels in developing countries. But burning these biomass fuels causes pollutants - such as carbon monoxide, particulate matter, sulfur dioxide and nitrogen dioxide - to be released into the air.
These air pollutants are associated with an increased risk of chronic obstructive pulmonary disease (COPD), impaired lung function and other respiratory disorders.
The new study - conducted by researchers at China's Guanzhou Medical University - set out to measure the long-term effects of replacing biomass fuels with cleaner fuels and improved kitchen ventilation.
The researchers found that participants who used biogas or improved their kitchen ventilation had better lung function over the course of the 9-year study.
The researchers recruited 996 participants, aged 40 years and over, from 12 Chinese villages. They offered the participants access to "biogas" - a clean fuel made by composting biomass at room temperature in a biogas digester - and improved ventilation to their kitchens.
Whether the villagers adopted these modifications - and to what extent they adopted them - was up to them.
Lung function of the participants was measured at the start of the study and at its end 9 years later. Air quality was tested in a random subset of the homes in the study, and lifestyle details of the participants were also recorded.
The researchers found that the participants who either used biogas or improved their kitchen ventilation had better lung function as they aged over the course of the 9-year study.
Additionally, the participants who adopted both biogas and improved ventilation did best of all in lung function tests and were shown to be less likely to develop COPD.
Lack of control group renders findings inconclusive
This was a long-term study with a relatively large sample base, but there were some drawbacks to the research. The main problem was that there was no control group in the study - a randomly selected group of participants who would not receive the biogas or improved ventilation.
Without a control group, the study's findings are not quite as reliable as they would be otherwise.
Instead, it was up to the participants whether they adopted the biogas and ventilation, and the lung function of the non-adopters was compared with the lung function of adopters to provide the study's results.
Consequently, the study is unable to conclusively prove that it was these interventions that caused the improved lung function and lower rates of COPD, but it does suggest that these things can help to reduce indoor air pollution and improve health.
The authors write that:
"...while we recognize that implementing community interventions to change how individuals cook in rural settings in developing countries remains a challenging task, substituting biogas for biomass fuel for cooking and improving kitchen ventilation could lead to a reduction of the global burden of COPD, especially in non-industrialized nations."