The effects of road pricing on driver behavior and air pollution  (Journal of Urban Economics)
with Maria Carnovale
Exploiting the natural experiment created by an unanticipated court injunction, we evaluate driver responses to road pricing. We find evidence of intertemporal substitution toward unpriced times and spatial substitution toward unpriced roads. The effect on traffic varies with public transit availability. Net of these responses, Milan's pricing policy reduces air pollution substantially, generating large welfare gains. In addition, we use long-run policy changes to estimate price elasticities.
Press: Seattle TimesCitylab from The Atlantic | BU Transportation Nudges (non-technical, w/video)
Gray matters: air quality and human capital formation (Journal of the Association of Environmental and Resource Economists)
with Prashant Bharadwaj, Joshua Graff Zivin, and Christopher Neilson
This paper examines the impact of fetal exposure to air pollution on 4th grade test scores in Santiago, Chile. We rely on comparisons across siblings which address concerns about locational sorting (for non-movers) and all other time-invariant family characteristics that can lead to endogenous exposure to poor environmental quality. We also exploit data on air quality alerts to help address concerns related to short-run time-varying avoidance behavior, which has been shown to be important in a number of other contexts. We find a strong negative effect from fetal exposure to carbon monoxide (CO) and correlated pollutants (like PM10) on math and language skills measured in 4th grade. These effects are economically significant and our back of the envelope calculations suggest that the 50% reduction in CO in Santiago between 1990 and 2005 increased lifetime earnings by approximately 100 million USD per birth cohort.

Time Use and Labor Productivity: The Returns to Sleep (forthcoming, The Review of Economics and Statistics)
with Jeffrey Shrader
We investigate how the single largest use of time—sleep—affects labor productivity. Motivated by a theoretical model, we provide empirical evidence that sleep is complementary to work in the short run and complementary to home production for non-employed individuals in both the short and long run. Using time use diaries from the United States, we show that later sunset time reduces worker sleep and earnings. After investigating these relationships and ruling out alternative hypotheses, we implement an instrumental variables specification that provides the first causal estimates of the impact of sleep on earnings. A one-hour increase in location-average weekly sleep increases earnings by 1.1% in the short run and 5% in the long run.
Press: WSJ | Huffington Post | Freakonomics | Marketplace | The World Bank | Australian Broadcasting Corporation LA Times NY Magazine Marginal Revolution Washington Post Daily Mail

Regulation-induced pollution substitution (accepted, The Review of Economics and Statistics)
Environmental regulations may cause firms to re-optimize over pollution inputs. By regulating air emissions in particular counties, the Clean Air Act (CAA) gives firms incentives to substitute: 1) toward polluting other media, like waterways; and 2) toward pollution from plants in other counties. I test these hypotheses using the EPA Toxic Release Inventory (TRI). Regulated plants increase their ratio of water to air emissions by 177 percent (102 log points) and their level of water emissions by 105 percent (72 log points). Regulation of an average plant increases air emissions at unregulated plants within the same firm by 11 percent.