Prof Kim's research, "The air quality effects of Uber,” was accepted for publication in the Journal of Urban Economics.

Prof. Kim and his colleague estimate the causal effect of the entry of ride-sharing services, such as Uber, on air quality across US cities using the staggered introduction of these services across cities. They find that Uber improves air quality: the air quality index declines by approximately 1–2% in the year of entry, and the probability of unhealthy air quality episodes falls by 8–18% following its introduction. They provide suggestive evidence that these improvements result from substituting trips in older, less efficient vehicles with Uber rides.