Contingent valuation method (CVM) is an economic tool used for estimating the value that a person places on environmental goods and services. CVM is particularly useful for estimating the value of non-market and non-use goods and services. The air pollution is one of the most important problems in Macao. Researchers interviewed sampled population by a particular action, and through a series of questions and analyses, estimate the respondent's value of the resource or action in terms of willingness to pay (WTP) or willingness to accept (WTA). Willingness to pay represents the most a person would be willing to pay to keep his or her quality of life, while willingness to accept represents the minimum that a person would be willing to accept to keep his or her quality of life at its original level when his or she loses the good. The research objective was adopting WTP and WTA method to analysis and to compare the value changes for respondent willing about the air pollution. The survey was performed two times through telephone. One survey was carried out with WTP before SARS (Severe Acute Respiratory Syndrome) in December, 2002; survey samples were 1600 with 720 effective samples colleted; the other with WTA after SARS in March, 2004; survey sample 1336 with 543 effective samples collected. The research aim was to estimate the value of the air pollution losses in Macao.
    The economic analysis result showed that the air pollution value losses of Macao was about 377 million MOP (The currency money in Macao, 1 USD = 8.033 MOP) per year before SARS by use WTP methods (about  0.69% of the GDP in the same year), and 1432 million MOP per year by use the WTA method after SARS (about 0.69% of the GDP in the same year). The result indicated that the citizen's environmental comsciousness increased after SARS.