This paper previously circulated as 'Private Actions in the Presence of Externalities: The Health Impacts of Reducing Air Pollution Peaks but not Ambient Exposure.' For generous financial support we thank the Weiss Family Program Fund, the International Growth Centre, UC Berkeley, Chicago Booth, Penn Global, and the Kleinman Center for Energy Policy. We thank Robert Bailis, Fiona Burlig, Pascaline Dupas, Reto Gieré, Joshua Graff Zivin, Stephen Harrell, Koichiro Ito, Darby Jack, David Levine, Alex Rees-Jones, Ajay Pillarisetti, Reed Walker, Catherine Wolfram, numerous seminar participants, and the late Kirk Smith for helpful comments. We thank Busara (in particular Suleiman Amanela and Debra Opiyo) for superbly implementing field activities; Berkeley Air (in particular Michael Johnson, Ashlinn Quinn, and Heather Miller) for assistance designing and implementing air pollution monitoring protocols; and Kamen Velichkov, Martín Serramo, and Adi Jahic for excellent research assistance. This study has IRB approval in Kenya (KEMRI/RES/7/3/1 and AMREF ESRC P1195/2022) and the US (University of Chicago IRB22-0943). To prevent increased Covid-19 transmission, all surveys conducted by this research team in 2020 were conducted via phone or SMS. A disclosure statement is available at https://sberkouwer.github.io/disclosureBDhealth.pdf. A pre-results proposal (available at https://sberkouwer.github.io/BerkouwerDean_Health_PAP.pdf) for this paper was accepted by the Journal of Development Economics. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.