By the mid-2000s, air pollution had become a serious public health and economic concern in Hong Kong. Cases of asthma and bronchial infections had soared due to reduced air quality. Research by the
University of Hong Kong School of Public Health estimated that air quality improvement to
World Health Organization guideline levels could avoid over 1,300 deaths, 60,000 hospital bed days, and 6.7 million doctor visits for respiratory complaints each year, with direct costs and productivity losses avoided of over US$240 million annually. The pollution crisis was driven by multiple factors including emissions from diesel vehicles, coal-fired power stations, and transboundary pollution from factories in the
Pearl River Delta. In November 2006,
Merrill Lynch downgraded several Hong Kong property companies including
Hongkong Land,
Great Eagle, and
Hysan Development because of air quality concerns, with analyst Spencer White writing that "the air quality in Hong Kong is now regularly so poor that the long-term competitiveness of this city is, in our minds, in some doubt." The campaign was part of broader efforts by the Hong Kong and
Guangdong governments to address regional air quality. Earlier in 2003, the two governments had established the PRD Regional Air Quality Management Plan, and the
Pearl River Delta Regional Air Quality Monitoring Network commenced operation in late 2006. ==Launch==