A study conducted as part of the
Transportation , Equity , Climate and Health project ( TRECH ), a multi-university research initiative , revealed that vehicle emissions in the Northeast and Mid-Atlantic regions of the US led to an estimated 7,100 deaths . The detrimental effects of pollution from tailpipe emissions extend beyond city and state boundaries , affecting the health of people residing in downwind areas . The Environmental Protection Agency ( EPA ) attributes 45 % of air pollution to the transportation sector . Highlighting the seriousness of traffic pollution , 2021 research by Harvard University emphasised that vehicle emissions have significant health impacts in all states and implementing local measures can bring about substantial health benefits .