Alex Dangel

Hi there!

I am a researcher at Heidelberg University’s Research Center for Environmental Economics. I study the economics of low-cost environmental sensors and behavioral responses to environmental health risks using field experimental and quasi-experimental methods.

Working Papers

• This paper studies temporal factors influencing the effectiveness of don't drive appeals (DDAs) which policy-makers use to encourage motorists to voluntarily reduce driving during transitory high pollution episodes. We derive and empirically validate a theoretical framework for DDAs where the desired behavioral response is sensitive to the number of consecutive DDA days and recovery time between episodes. Our analysis of daily traffic flows from automatic traffic counters in Stuttgart, Germany shows that DDAs at best reduce overall car trip demand during pollution events by less than 1% on average, but treatment effects vary. Difference-in-difference event study estimates reveal that DDAs: i) lead to approximately 3% traffic reductions on the first three days of DDAs and taper off in effectiveness during longer episodes, ii) regain effectiveness at the tail end of DDA episodes once local authorities announce when they will be lifted, and iii) only reduce city center traffic following lengthy recovery periods between events. Our findings provide evidence that temporal factors like social norms and intertemporal substitution dynamically affect voluntary short-term pollution mitigation programs. They also confirm prior North American evidence on DDA traffic displacement and limited overall impact in a European setting.

In Progress

Now It’s Personal: A Field Experiment on the Demand for Wearable Air Quality Sensors with US Early Adopters (with Timo Goeschl)

• Wearable air quality sensors offer consumers the ability to monitor and respond to personal pollution exposure in real-time, potentially informing behavioral responses to health risks and supplying novel data that can be used to assess population exposure to harmful pollutants. In partnership with a leading manufacturer, we conduct a field experiment in the United States to study demand, use, and impacts of this emerging technology among early adopters. Through a point-of-sale survey and a pricing experiment, we find that mean willingness-to-pay falls short of current market prices, and advantaged groups dominate prospective and actual customer bases. Leveraging natural variation in ambient air quality, we show that demand and user activity increase during unhealthy pollution events. Limited follow-up data suggests that adopters update their beliefs about pollution exposure, substitute public air quality information with private sensor data, and maintain the frequency of defensive behaviors. Our results provide valuable insights for developing pollution monitoring systems and highlight the importance of equitable access to environmental information and adaptation opportunities.

Mind the PM2.5 Gap! Comparing Pollution Exposure Estimates from Wearable Sensors and Ambient Monitors

• Typically, environmental health studies either track personal exposure to harmful pollutants for a small number of individuals or rely on secondary data that insufficiently proxies for true exposure. In this paper, I construct a highly granular, geolocated air pollution dataset at previously unavailable scale by leveraging over 45 million personal PM2.5 (fine particulate matter) exposure readings from a consumer sample of 594 wearable air quality sensor users in the United States. I exploit this novel dataset and natural variation in ambient air quality to assess bias in commonly used PM2.5 secondary data from fixed ambient monitors. On average, personal exposure in my sample is between 7% and 18% less than monitor-based estimates, while median differences correspond to nearly 40% less pollution. Moreover, my analysis shows that this "PM2.5 gap" varies systematically with pollution levels, location, and time. These findings underscore significant heterogeneity in pollution exposure and suggest that previous research relying on monitor data may misstate the relationship between pollution and damages.

Stationary Air Quality Sensor Adoption: The Role of Socioeconomics, Government Monitors, and Nearby Sensors (with Timo Goeschl)

Upcoming Presentations

• June 2025: EAERE Summer Conference in Bergen, Norway.

Recent Presentations

• June 2025: ZEW-Heidelberg-Mannheim Environmental Economics Brownbag Seminar.
• May 2025: Mannheim Conference on Energy and the Environment in Mannheim.
• May 2025: AERE@OSWEET.
• March 2025: CESifo / ifo Junior Workshop on Energy and Climate Economics 2025 in Munich.