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1. Introduction
Hong Kong (HK), a city located on the Southeast coast of China, is the first Special Administrative Region (SAR) established under the policy of “One Country, Two Systems” [1]. Before the sovereignty was handed back to China on 1 July 1997, HK had been one of the colonies of the United Kingdom since 1842 [2]. With plenty of resources and support provided by The British government, HK has become one of the most civilized cities and largest financial centers in the world [3].
Gifted with the wonderful geographical location in Asia-Pacific region and the renowned deep-water harbor between Hong Kong Island and Kowloon Peninsula, HK is also one of the biggest import and re-export centers on the globe, acting as a bridge to associate between Mainland China and other countries in Asia, Europe and Latin America [2,4]. HK’s GDP per capita was USD$43,500 in 2016, according to the HK government’s data, with the amount of USD$513.9 billion from import and USD$454.5 billion from re-export [5].
After a series of wars, natural disasters and socio-political movements led to millions of immigrants moving to HK from Mainland China. As a result, the population has increased dramatically in the recent decades. The population of HK jumped from 456,739 in 1911 to 3,129,648 in 1961 and 7,071,576 in 2011, over 15-fold in 100 years [6]. Along with the population explosion, large amount of public and private residential housings were built in 1940’s and 1950’s to satisfy the need. Similar to other developed countries in the world, a substantial proportion of those buildings built in the early years used asbestos-containing materials (ACMs); and the peak period of adopting large amount of asbestos for building construction was in 1960’s [7]. According to a previous study, the yearly use of asbestos per capita was about 8.84 kg/capita/year in 1960-1963, and this number dropped to less than 1 kg/capita/year after 1986 [7].
As there is neither asbestos ores nor asbestos or ACMs produced in HK, all the ACMs used in HK were imported. These ACMs in HK were commonly found as corrugated cement sheets for roofing, wall board, cement roof tiles, vinyl floor coverings and the stuffing inside cable trays [8]. Based on the statistics released by the Environmental Bureau of...