BACKGROUND: Cooking practice has transitioned from use of solid fuels to use of clean fuels, with addition of better ventilation facilities. However, the change in mortality risk associated with such a transition remains unclear.
METHODS: The China Kadoorie Biobank (CKB) Study enrolled participants (aged 30-79 years) from ten areas across China; we chose to study participants from five urban areas where transition from use of solid fuels to clean fuels for cooking was prevalent. Participants who reported regular cooking (weekly or more frequently) at baseline were categorised as persistent clean fuel users, previous solid fuel users, or persistent solid fuel users, according to self-reported fuel use histories. All-cause and cardiopulmonary mortality were identified through linkage to China's Disease Surveillance Point system and local mortality records.
FINDINGS: Between June 24, 2004, and July 15, 2008, 226 186 participants living in five urban areas of China were enrolled in the CKB Study. Among 171 677 participants who reported cooking regularly (weekly or more frequently), 75 785 (44%) were persistent clean fuel users, 80 511 (47%) were previous solid fuel users, and 15 381 (9%) were persistent solid fuel users. During a mean of 9·8 (SD 1·7) years of follow-up, 10 831 deaths were documented, including 3819 cardiovascular deaths and 761 respiratory deaths. Compared with persistent clean fuel users, persistent solid fuel users had significantly higher risks of all-cause mortality (hazard ratio [HR] 1·19, 95% CI 1·10-1·28), cardiovascular mortality (1·24, 1·10-1·39), and respiratory mortality (1·43, 1·10-1·85). The excess risk of all-cause and cardiopulmonary mortality fell by more than 60% in 5 years after cessation of solid fuel use and continued to decrease afterwards. Use of ventilation was associated with lower all-cause mortality risk, even among persistent clean fuel users (HR 0·78, 0·69-0·89).
INTERPRETATION: Solid fuel use for cooking is associated with a higher risk of mortality, and cessation of solid fuel use cuts excess mortality risks swiftly and substantially within 5 years. Ventilation use also lowers the risk of mortality, even among people who persistently use clean fuels. It is of prime importance for both policy makers and the public to accelerate the transition from solid fuels to clean fuels and promote efficient ventilation to minimise further adverse health effects.
FUNDING: National Natural Science Foundation of China, Wellcome Trust, and Kadoorie Charitable Foundation.
Bibliographical noteThis is an Open Access article under the CC BY 4.0 license.
FunderThis work was supported by grants from the National Natural Science Foundation of China ( 91843302 , 91643202 , and 81390540 ), the Foundation of National Key Program of Research and Development of China ( 2016YFC0900800 ), the 111 Project and the Program for Changjiang Scholars, Innovative Research Team in University, and the Fundamental Research Funds for the Central Universities ( 2019kfyXMBZ015 ). The China Kadoorie Biobank baseline survey and the first resurvey were supported by the Kadoorie Charitable Foundation in Hong Kong. Long-term follow-up is supported by the UK Wellcome Trust ( 088158/Z/09/Z and 104085/Z/14/Z ), the National Key Research and Development Program of China ( 2016YFC0900500 , 2016YFC0900501 , and 2016YFC0900504 ), and the Chinese Ministry of Science and Technology ( 2011BAI09B01 ). The British Heart Foundation, UK Medical Research Council, and Cancer Research provide core funding to the Clinical Trial Service Unit and Epidemiological Studies Unit at Oxford University for the project.
- Cardiovascular Diseases/mortality
- Cause of Death
- Fossil Fuels
- Lung Diseases/mortality
- Middle Aged
- Prospective Studies
- Urban Population/statistics & numerical data