Development of an Aggregate Air Quality Index Using a PCA-Based Method: A Case Study of the US Transportation Sector

Abstract

For the past couple of decades, the transportation sector has made efforts to preserve and improve air quality for public health and sustainable growth between current and future generations. An easily understandable tool to measure the level of air pollution in the transportation sector by considering multiple air pollutants together might raise awareness about clean air to the public, practitioners, state policy planners, and the government. For this reason, this study develops an aggregate air quality index to help prepare decision makers, which could rank a state according to the different levels of multiple air pollutants. The index is developed for use with principal com-ponent analysis and an algebra about a line segment, and then applied to the US transportation sector using data on five air pollutants (CO, NOx, PM, SO2, and VOCs) in 2008. This study finds that some states were less polluted or more polluted in terms of the index, although their GDP levels for a transport mode were similar to each other. Thus, this finding implies that the necessary actions for stricter air quality standards must be taken in their boundaries.