Effects of LPG and Ventilation Interventions on Reducing HAP and Improving Cardiopulmonary Health

The goal of this clinical trial is to evaluate the independent and synergistic effects of liquefied petroleum gas (LPG) substitution and improved ventilation on household air pollution (HAP) reduction and cardiopulmonary health. The main questions it aims to answer are: 1. Does LPG substitution or improved ventilation reduce HAP and improve cardiopulmonary health? 2. Would the combined intervention of LPG substitution and improved ventilation outperform single interventions? 3. What is the cost-effectiveness of such interventions, and are they sustainable? 4. Does the intervention reduce the incidence of cardiopulmonary clinical events? Participants will be randomized in 4 groups: A: Solid fuel + no ventilation facilities group (300 households): Continued use of solid fuels without installation of ventilation facilities and receipt of standardized health education. No LPG stoves or ventilation equipment will be provided during the intervention period. However, after the primary endpoint assessment at 12 months, all households in Group A will be provided with LPG stoves and ventilation facilities of equivalent specifications free of charge, along with health guidance. Phased cash compensation will be provided during the intervention period. B: Liquefied petroleum gas (LPG) + no ventilation facilities group (300 households): Provided with LPG stoves and instructed to use them during cooking, with regular LPG supply throughout the intervention period. Participants will also receive standardized health education. C: Solid fuel + ventilation facilities group (300 households): Continued use of solid fuels while being provided with ventilation facilities and instructed to use them during cooking. Electricity costs will be compensated during the intervention period. Participants will also receive standardized health education. D: LPG + ventilation facilities group (300 households): Provided with both LPG stoves and ventilation facilities and instructed to use both during cooking. Regular LPG supply and electricity cost compensation will be provided throughout the intervention period. Participants will also receive standardized health education.