Transition of cooking fuel types and mortality risk in China, 1991-2015

Transition of cooking fuels and obesity risk in Chinese adults

BACKGROUND

Since 1990 s, China has witnessed a widespread transition to clean cooking fuels, presenting an opportunity to investigate whether household fuel transition could mitigate obesity risk and reconcile inconsistencies in the literature regarding the association between cooking fuels and obesity.

METHODS

The China Health and Nutrition Survey (CHNS) is a prospective cohort study covering 12 provinces of China (1989-2015). Participants were classified into persistent cleaner fuel users, fuel transitioners, and persistent polluting fuel users according to self-reported primary cooking fuels. Obesity and central obesity were defined as BMI ≥ 28.0 kg/m2 and waist circumference ≥ 90 cm in men and ≥ 85 cm in women according to Chinese criteria.

FINDINGS

Among 13,032 participants, 3657 (28.06 %) were persistent cleaner fuel users; 5264 (40.39 %) transitioned from using polluting fuels to cleaner fuels after the baseline survey; and 4111 (31.55 %) were persistent polluting fuel users. During the period of follow-up of 9.0 ± 6.8 years, 1248 (9.58 %) participants were classified into the obesity category, and 4703 (36.09 %) into the central obesity category. Persistent polluting fuel users had a significantly higher risk of developing obesity (hazard ratio [HR]: 1.45, 95 %CI: 1.22-1.72) and central obesity (HR: 1.32, 95 %CI: 1.21-1.44), compared to persistent cleaner fuel users. Persistent polluting fuel use was positively associated with developing obesity in women (HR: 1.64, 95 %CI: 1.30-2.06), but not in men. Subgroup analyses showed higher HR of persistent polluting fuel use among individuals aged 18-44 years (HR: 2.04, 95 %CI: 1.62-2.56). In contrast, the transitioners did not exhibit a significantly different risk of developing obesity (HR: 0.94, 95 %CI: 0.80-1.10) compared to persistent cleaner fuel users, which was consistent across different sex, age and urbanicity. Similar trends were observed for developing central obesity.

INTERPRETATION

Persistent polluting fuel use increased obesity risk while the obesity risk of the transition to cleaner fuels was similar to persistent use of cleaner fuels. The finding underscores the significance of advocating for the adoption of cleaner fuels as a strategy to mitigate the disease burden associated with obesity.

Associations between cooking fuels and hypertension prevalence in Chinese adults: A prospective cohort analysis focusing on fuel transitioning

BACKGROUND

Using polluting cooking fuels is a suggested risk factor for hypertension. Transitioning to clean cooking fuels has occurred widely in China in the past 30 years. This provides an opportunity to examine whether the transition could reduce hypertension risk and to ascertain the inconsistent literature on the relationship between cooking fuels and hypertension prevalence.

METHODS

Initiated in 1989, the China Health and Nutrition Survey (CHNS) enrolled participants from 12 provinces in China. By 2015, nine waves of follow-up have been conducted. Based on self-reported cooking fuels, participants were classified into persistent clean fuel users, persistent polluting fuel users and those who transitioned from polluting fuels to clean fuels. Hypertension was defined as having systolic blood pressure (SBP) ≥ 140 mmHg, diastolic blood pressure (DBP) ≥ 90 mmHg, or self-reported current use of antihypertension medication.

FINDINGS

Among 12,668 participants, 3963 (31.28%) were persistent polluting fuel users; 4299 (33.94%) transitioned to clean fuels; and 4406 (34.78%) were persistent clean fuel users. During the period of follow-up (7.8 ± 6.1 years), hypertension was diagnosed in 4428 participants. Compared to persistent clean fuel users, persistent polluting fuel users had a higher risk for hypertension (hazard ratio [HR] 1.69, 95%CI 1.55-1.85), while those transitioned to clean fuels did not. The effects were consistent by gender and urbanicity, respectively. The HRs for hypertension were 1.99 (95%CI 1.75-2.25), 1.55 (95%CI 1.32-1.81) and 1.36 (95%CI 1.13-1.65) among those persistent polluting fuel users aged 18-44, 45-59 and ≥60 years old, respectively.

INTERPRETATION

Transitioning from using polluting fuels to clean fuels prevented an increase in hypertension risk. The finding highlights the importance of promoting the fuel transition as a risk-reduction strategy for reducing the disease burden from hypertension.