Assessment of Air Quality Impact of Traffic Congestion in Urban Environment

Residents of metropolitan areas and urban environments around the globe are constantly dealing with issues of air quality and traffic congestion. The air quality in New York City (NYC) and other cities around the U.S. has improved since 1970 as a result of the clean air regulations of the US Environmental Protection Agency (EPA). Despite these improvements, routine air sampling done by the New York State Department of Environmental Conservation (NYSDEC) has shown that NYC still does not meet the federal clean air standards. Comprehensive studies by the NYSDEC has shown that major air pollutants—including fine particles, elemental carbon, various oxides of nitrogen, sulfur dioxide, and ozone—varied more than two-fold across the city. These studies have also shown that higher concentrations tend to occur in areas where fuel combustion sources, especially emissions from on-road vehicles and buildings, are more abundant. Research in NYC and other locations around the world has linked these pollutants to adverse health effects, especially in children, elderlies and individuals with respiratory or cardiovascular conditions. PM2.5 includes airborne, solid and liquid materials with a diameter smaller than 2.5 micrometers that are emitted from motor vehicle engines particularly those using diesel fuels have a higher rate of emission. Elemental carbon is one component of PM2.5 that should be measured separately because it has a dominant role in the irritation of the breathing passages and the exacerbation of respiratory symptoms such as cough or asthma. Additionally, elemental carbon may increase the risk of cancer and can trigger allergies to pollens and other substances in the environment. This study provides a basis for improving the understanding of the localized interactions between traffic congestion and air quality by presenting an alternative approach that would extend the temporal resolution of the data from daily to continuous measurements in order to correlate fluctuation in traffic patterns to air quality across NYC. Environmental data has been collected through portable weather stations equipped to measure PM2.5, elemental carbon, solar irradiance, temperature, relative humidity, wind direction and speed. The PM2.5 data collected is averaged in 10 minute intervals for noise reduction, and is both communicated wirelessly as well as and logged locally for periodic retrieval. Traffic monitoring data has been collected using microwave sensors that measure volume, occupancy, and individual vehicle speed. Such detailed information regarding the relationship of traffic and air pollution will enable increased public awareness of small-area variations in air pollution exposures from traffic in NYC. This work was funded by The University Transportation Research Center (UTRC) of U.S. Department of Transportation (DOT).