Effects of Vehicular Emissions on Urban Air Quality in Ecuador and Implications for Respiratory Health

Vehicular emissions are a major contributor to air pollution and respiratory morbidity in Ecuador’s urban centers. Despite increasing evidence of traffic-related health impacts, national research remains fragmented and unevenly distributed. This narrative review synthesizes 26 peer-reviewed studies published between 2000 and 2024 to characterize vehicular air pollution sources, pollutants, and respiratory health effects in Ecuador. The evidence shows a strong geographic concentration, with more than half of the studies conducted in Quito, followed by Guayaquil and Cuenca. National inventories indicate that the transport sector accounts for approximately 41.7% of Ecuador’s CO 2 emissions. Across cities, PM 2.5 , PM 10 , NO 2 , CO, and SO 2 were the most frequently assessed pollutants and were repeatedly reported to approach or exceed international guideline values, particularly during traffic peaks and under low-dispersion conditions. Health-related studies documented substantial impacts, including up to 19,966 respiratory hospitalizations in Quito, with short-term PM 2.5 exposure associated with increased hospitalization risk in children. Among schoolchildren attending high-traffic schools, carboxyhemoglobin levels above 2.5% were linked to a threefold increase in the risk of acute respiratory infections. Occupationally exposed adults, such as drivers, traffic police officers, and outdoor workers with regular exposure to traffic-related air pollution, also showed a higher prevalence of chronic respiratory symptoms. Environmental evidence further highlighted the accumulation of traffic-related heavy metals (Zn, Cu, Pb, Cr) and pronounced spatial inequalities affecting low-income neighborhoods. Overall, the review identifies aging vehicle fleets and diesel-based transport as dominant contributors to observed pollution and health patterns, while underscoring methodological limitations such as the scarcity of longitudinal studies and uneven monitoring coverage. These findings provide integrated and policy-relevant evidence to support sustainable urban planning, cleaner transport strategies, and targeted respiratory health policies in Ecuador.