In 2014, the World Health Organization found poor air quality to be a leading cause of premature death. People who live near highways, train lines, shipping lanes, and airports are exposed to significant concentrations of pollutants generated by combustion engines, such as Ultrafine Particles (UFPs), which are associated with long-term negative health effects such as asthma and cancer.

In Boston, neighborhoods closest to these pollution sources are often inhabited by underrepresented populations and low-income households, meaning that these residents are disproportionately affected by poor air quality.