Polycyclic aromatic hydrocarbons (PAHs) were determined in the air of 37 cities and 3 rural locations across China during the winter, spring, summer and autumn of 2005, using polyurethane foam (PUF) disks as passive air samplers (PAS). Winter and autumn concentrations in cities exceeded spring and summer values. Concentrations were amongst the highest in the world; seasonally averaged autumn/winter values in some cities in the north and north-west of China exceeded proposed European Union air quality standards. Several factors, acting in combination, influenced air concentrations. A significant negative correlation was found between average annual city concentrations and the annual average temperature, while winter time PAH concentrations correlated with estimated coal consumption. The highest total PAH concentrations and loadings of high molecular weight compounds generally occurred in major cities located on higher land (500-2000 m), where relatively cold winters and higher coal consumption occurs. Lower values occurred in cities located in the south and east China and along the coastal regions. Molecular markers indicated incomplete combustion of fossil fuels dominated the urban air and gave evidence for photo-decomposition of selected compounds.

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Green credit is not only a financial leverage which promotes environmental protection, it is also an inevitable choice for financial institutions to evade their environmental risks, and the environmental credit assessment is a critical link for implementation of green credit. Based on analysis of various factors affecting enterprises’environmental credit level, this paper designs the indicators of environmental credit assessment, and builds the model for enterprises' environmental credit assessment with AHP(analytic hierarchy process) in order to provide financial institutions with a technical method for environmental credit assessment so as to promote implementation of green credit smoothly and evade the environmental risks in the field of credit effectively.

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