How Do Household Energy Interventions Work?
Sam Harper1, Chris Barrington-Leigh1, Ellison Carter2, Arijit Nandi1, Robert Platt1, Brian Robinson1, Shu Tao3, Yuanxan Zhang4, Jill C. Baumgartner1
1McGill University, Montreal, QC, Canada; 2Colorado State University, Fort Collins, CO, USA; 3Peking University, Beijing, China; 4University of the Chinese Academy of Sciences, Beijing, China
Background: Extensive evidence links air pollution with a range of health outcomes in adults and children, but understanding the effectiveness of regional interventions and policies in reducing air pollution and improving health remains a challenge. Coal heaters are an important source of indoor and outdoor air pollution in China, where winter smog episodes and high levels of ambient air pollution have motivated a number of ambitious policy actions aimed at reducing regional emissions and improving air quality. As part of its “war on pollution,” the Chinese government mandated that over 1.5 million residents in 3,700 villages in the Beijing region must switch from highly polluting coal heaters to efficient electric or gas-powered heat pumps between 2017 and 2021, and simultaneously instituted a subsidy program for the heat pumps. This policy is being rolled out village-by-village from 2017-2021, offering a unique opportunity to leverage this natural experiment and assess the effectiveness of the coal ban and heat pump subsidy in reducing air pollution and improving health.
Methods: We will integrate advanced methods in mediation analysis with a quasi-experimental impact evaluation, which is critical for understanding how interventions may improve air quality and health. Based on three winter seasons of field data collection in 50 villages, we will: 1) Estimate how much of the policy’s overall effect on health, including respiratory symptoms and cardiovascular outcomes (blood pressure, central hemodynamics, blood inflammatory and oxidative stress markers), can be attributed to its impact on changes in PM2.5; 2) Assess the effect of alternative pathways and mechanisms, other than air pollution, that may contribute to the policy’s impact on health outcomes; and 3) Quantify the impact of the policy on outdoor air quality and personal exposures, and specifically the source contribution from household coal burning.
Expected Results: We are using a difference-in-differences research design to estimate the overall impact of the program, as well as detailed measurements of the potential behavioral, environmental, and chemical mechanisms that may explain how the policy affects health outcomes. Because regional and local air quality interventions can produce multiple behavioral, environmental, and health-related changes, it is important to investigate the specific mechanisms through which policies exert their health impacts. The health benefits achievable with transition to a new home heating system, for example, may be influenced by factors including outdoor air quality, the desirability and use of new heaters, maintenance of indoor temperature, and related behaviors including physical activity and dietary intake. Only recently have these mediating factors been considered in assessments of household energy interventions and health, and even more rarely in a comprehensive way. Understanding these direct and indirect mechanisms will provide valuable scientific insight into the success (or failure) of the coal ban and heat pump policy in meeting its air quality and health goals, and may answer questions that help to design more effective future air quality interventions.