Evaluating the effectiveness of air pollution policies in Hong Kong : accountability studies

Abstract

Accountability studies can be used to quantify whether, and to what extent air quality policies, improve air quality and health. Hong Kong is a very policy rich setting. Over the last three decades the government has implemented numerous air quality policies designed to reduce air pollution and improve population health. However, accountability studies have only been conducted on earlier policies using traditional observational study designs, such as comparing health outcomes in people with different exposures, and none have been conducted on the most recent policies. This thesis focuses on the evaluation of several air pollution policies implemented in Hong Kong, using a quasi-experimental design which provides more rigorous policy evaluation. On July 1st, 1990, the Hong Kong government implemented a policy requiring all road vehicles and power plants to use a fuel with a sulfur content of no more than 0.5%. Previous studies have reported a decrease in respiratory and cardiovascular diseases following that policy, essentially using a before and after comparison that did not take into account any secular trends. The aim of this study was to re-evaluate this policy using a quasi-experimental design, i.e., an instrumental variable analysis design with the policy change as the instrument, implemented as an interrupted time series (ITS) to account for secular trends. Immediately after the policy was implemented a small decline occurred specifically for respiratory diseases. No other changes occurred for any other major disease, indicating small short-term benefits. On December 30th, 2013, the Hong Kong government introduced the Air Quality Health Index (AQHI) alert programme, with the aim of using warnings to reduce the short-term effects of poor air quality on health. Whether air quality alert programs, like the AQHI, reduce hospital admissions are still questionable. Using ITS to identify short- and long-term changes from 2010-2016 in emergency respiratory hospital admissions, I discovered, the AQHI lead to a reduction of hospital admissions in children, particularly for RTI and pneumonia, and hypertensive disease (HPD) and acute myocardial infection (AMI) in older people. No change for overall cardiovascular disease (CVD) or other sub-types was found. The first policy in Asia to regulate sulfur dioxide (SO2), was implemented in Hong Kong, on July 1st, 2015. Using two complementary methods— ITS with segmented regression and CUSUM charts— I conducted an accountability study assessing the improvement in ambient air quality (SO2 compared to other ambient pollutants PM10, NO2 and ozone O3). A health assessment was also conducted to estimate the policy effect on health outcomes. The Hong Kong’s shipping emission policy successfully reduced ambient SO2, likely with correspondingly lower local mortality. In summary, accountability studies are needed in Hong Kong and these studies are an effective way to measure the impact of air pollution policies, if appropriate studies are planned, and appropriate methods are used.

An abstract of exactly 460 words