Research

Publications 

1.  "Air Pollution Exposure and Donation to Its Victims: Evidence From Online Charitable Giving" (with Peng Shen, Xincheng Wang, Yinxiao Wang, Yucheng Wang and Shuhuai Zhang) Journal of Environmental Economics and Management (2025): 103245.

2.  "Modeling Behavioral Response to Infectious Diseases Under Information Delay” (with Haosen He and Frederick Chen) Review of Economic Design (2025): 1-22.

3. "Observational Studies Generate Misleading Results About the Health Effects of Air Pollution: Evidence From Chronic Air Pollution and COVID-19 Outcomes." (with Marc N. Conte, Matthew Gordon,Nicole A. Swartwood,and Rachel Wilwerding) PloS One 19.1 (2024): e0296154.

4.  "An Agent-based Model of Elephant Crop Consumption Walks Using Combinatorial Optimization" (with Haosen He, Erin Buchholtz, Frederick Chen, and Susanne Vogel) Ecological Modelling  (2022): 464, 109852.  

5. "COVID-19's U.S. Temperature Response Profile"  (with Richard Carson, Samuel Carson, Thayne Dye, Samuel Mayfield, and Daniel Moyer) Environmental and Resource Economics (2021): 1-30. 

Working papers

"Mismeasured and Misunderstood: Unmasking the Temperature Proxy Problem in Climate Impact Estimates" with Richard T. Carson. Accepted at Journal of the Association of Environmental and Resource Economists.

Thousands of studies estimate prospective climate change impacts by examining how temperature affects a wide range of outcomes of interest. Potential measurement error in temperature variables is routinely ignored, and when acknowledged, typically assumed to be small in magnitude with a classical (i.i.d. normal) distribution, leading estimates to be attenuated toward zero. We formally document the sources of errors introduced in the construction of temperature proxy variables and show this widely held assumption is wrong using a best-case approach that treats readings at 1,120 U.S. weather stations as truth. Overall, the average downward bias in estimated impacts is substantial. However, due to the non-classical nature of the measurement errors, overestimates are not rare. Estimation problems are concentrated where attention focuses—the tails of the temperature distribution.

"Co-Pollutant Bias in Air Pollution IV Designs" with Zhenxuan Wang.  Under review.

This paper studies air pollution IV estimates when instruments move several pollutants simultaneously and provides diagnostic tools for interpreting them. We distinguish two interpretations: a stimulus effect of the named pollutant holding co-pollutants fixed, and a proxy effect of the pollution bundle indexed by that pollutant. An empirical evaluation shows that adding controls, swapping the focal pollutant, or jointly instrumenting multiple pollutants can still leave nontrivial bias. We derive conditions under which single- and multi-pollutant IV estimates support either interpretation and provide a framework for quantifying bias when they do not. A crime application illustrates the framework.

"Measurement Error Bias in Air Pollution IV Designs" with Zhenxuan Wang.  Under review.

Instrumental variables are often used to address measurement error in air pollution exposure. This paper shows why that logic can fail when thermal inversion instruments are paired with satellite-based PM2.5. IV recovers the effect of true pollution only if proxy error is uncorrelated with the instrument. Using  monitor, satellite, reanalysis, and meteorological data, we show that satellite PM2.5 error is strongly predicted by thermal inversions. In a crime application, satellite-based proxies materially change IV estimates despite strong first stages. The key diagnostic is whether proxy error is orthogonal to the identifying variation.

"Exposure, Vulnerability and Environmental Injustice: Air Pollution and Emergency Medical Care in NYC" with Marc N. Conte and Rachel Wilwerding. Under review.

Air pollution can create inequitable environmental burdens through differences in hazard exposure and vulnerability. Using Emergency Medical Service (EMS) dispatch records from New York City, we find that air pollution significantly increases emergency responses, with larger effects in disadvantaged communities (DACs). Integrating EPA monitors with a denser local network improves measurement of within-city pollution exposure and reveals stronger pollution impacts in DACs than estimates based on EPA data alone. Under everyday pollution levels, disadvantaged communities show limited vulnerability to certain respiratory conditions, consistent with the use of accessible defensive technologies that reduce reliance on emergency care. During the 2023 Canadian wildfire smoke episode—an extreme event with similar outdoor exposure across neighborhoods—structural constraints reduced the effectiveness of these defenses, revealing greater vulnerability in DACs. These findings highlight the importance of improved monitoring and policies that reduce structural barriers to protection.

"Rerouting Externalities: Flight Diversions and Local Health" with Zhanhan Yu. 

Transportation networks absorb disruptions by rerouting activity, shifting local externalities toward communities that did not generate the disruption. We study this rerouting mechanism through flight diversions, linking flight diversion records to neighborhood Emergency Medical Services dispatches in New York City. Using disruptions elsewhere in the air network as an instrument for diversion exposure, we find that greater exposure increases EMS demand, especially in neighborhoods closest to airports and late-night diversions. Delayed scheduled arrivals generate markedly different responses, indicating that spatial reallocation, rather than late arrival alone, contributes importantly to the EMS response. The 2016 relaxation of slot controls at Newark Airport was followed by diversion activity shifting toward the region’s other major airports, and higher EMS demand in nearby communities. The findings illustrate how disruptions and airport-capacity policies can redistribute aircraft activity and associated health burdens across connected airports and surrounding communities.

Work in progress

"Unintended Digital Precaution in Extreme Weather" with Tin Cheuk Leung [slides]