Can the threat of regulation reshape a major consumer market before any regulation takes effect? We study this question using the staggered timing of lawsuits that an environmental organization filed against nearly 40 German cities between 2015 and 2021, targeting bans on older diesel vehicles. Using a difference-in-differences design, we find that the threat alone significantly reduces used diesel car registrations by 8–10 percent across all Euro standards, while shifting some demand toward middle-aged gasoline vehicles and lowering ambient nitrogen dioxide by roughly 8 percent in the affected places. Actually imposing the bans produces effects of similar sign and magnitude, but they are not statistically significant. That a regulatory threat alone can shift a market and improve air quality suggests that legal threats can be a meaningful instrument for achieving environmental outcomes in their own right. Because most sued counties never adopted a ban, evaluations that treat implementation as the starting point for measuring a threatened policy's effect would miss this response entirely.

Environmental regulations shape the spatial distribution of pollution, influencing the burden on different communities. In South Florida, wind-based sugarcane burning regulations have historically favored wealthier, densely-populated areas by limiting burning during specific wind conditions. In 2019, additional restrictions were introduced to limit burning on days with low air quality. By using satellite fire data and Aerosol Optical Depth (AOD) data, we assess the impact of these stringent restrictions on burning and air pollution. Results reveal a 41 percent decrease in burning on restricted days within the main cultivation area, potentially leading to increased burning on days without restrictions. This unintended consequence exacerbates air quality issues for the region’s most vulnerable populations. The study reveals regulatory enhancements inadvertently worsen environmental inequities, highlighting the need for environmental justice policies that address historical and systemic discrimination affecting pollution distribution.

Wildfire events have increased in frequency and severity across the United States in recent decades. While a growing literature has documented the effects of wildfire smoke exposure on a wide range of health and socioeconomic outcomes, little is known about its impact on consumer behavior and household demand for adaptation in healthcare. We combine a newly developed and digitized dataset on daily wildfire smoke PM2.5 concentrations across the contiguous United States during 2006-2019 with weekly Nielsen retail scanner data to quantify how wildfire smoke exposure affects retail sales of air purifiers, bottled water, cold remedies, nasal products, cough products, and nutritional products. We find a positive and statistically significant impact of wildfire smoke exposure on the retail sales of these products. Dynamic effects are evident as wildfire smoke exposure in previous weeks also increases current sales. Nonlinear effects arising from the varying intensity of wildfire smoke exposure also reveal distinct patterns of demand for adaptation. We further explore how the effects of wildfire smoke exposure vary with socio-demographic characteristics, focusing on social vulnerability and highlighting the implications of environmental justice. Our results underscore the need for proactive policies to address the increased demand for medical and healthcare products as household adaptive measures during the wildfire season, particularly targeting socioeconomically vulnerable populations who may be prone to limited access to other preventive measures against wildfire.

Adverse weather events significantly impact the operations of urban transportation systems and change human travel behaviors. Over the decades, wildfires have emerged as a pressing concern due to their increased frequency and intensity, yet the relationship between wildfire smoke and public transportation usage remains largely unexplored. Leveraging high-resolution daily wildfire-driven PM2.5 concentration estimates and station-level Metrorail ridership data in the Washington Metropolitan Area spanning 2012–2019, we examine the effects of wildfire smoke exposure on Metrorail usage. We find that wildfire smoke exposure results in a 0.8% increase in Metrorail ridership on weekdays and a more pronounced 3.7% rise on weekends. Additionally, we show a stronger response in Metrorail ridership to wildfire smoke during off-peak hours compared to peak hours, with the most substantial increase observed during the winter. Our heterogeneity analysis further suggests that a lack of vehicle ownership and higher reliance on walking and public transportation are key factors leading to increased Metrorail ridership. Collectively, these results highlight the need for proactive service adjustments and effective communication strategies to accommodate the potential shifts in human travel behaviors and Metrorail ridership on days exposed to wildfire smoke.