My research includes several different areas of environmental biostatistics, including:

I’m always looking to begin new collaborations, whether related to these topics or in a different area. Please contact me for more information.

For a complete list of publications, please see my Google Scholar page.

Spatiotemporal Prediction of Outdoor Air Pollution

In studies of the health effects of long-term air pollution exposure, measurements of air quality are generally unavailable at the same locations as cohort members. Spatial or spatiotemporal models allow exposures to be predicted at cohort locations. These exposures include not only concentrations of single pollutants, but also lower-dimension representations of multipollutant exposures using approaches such as clustering.

  • Keller JP, Drton M, Larson T, Kaufman JD, Sandler DP, and Szpiro AA. 2017. Covariate-adaptive clustering of exposures for air pollution epidemiology cohorts. Annals of Applied Statistics, 11(1), 93-113. doi:10.1214/16-AOAS992
    R Package ‘predkmeans’.
  • Keller JP, Olives C, Kim S-Y, Sheppard L, Sampson PD, Szpiro AA, Oron AP, Lindström J, Vedal S, and Kaufman JD. 2015. A unified spatiotemporal modeling approach for prediction of multiple air pollutants in the Multi-Ethnic Study of Atherosclerosis and Air Pollution. Environmental Health Perspectives, 123(4), 301-309. doi:10.1289/ehp.1408145
  • Wang M, Keller JP, Adar SD, Kim S-Y, Larson TV, Olives C, Sampson PD, Sheppard L, Szpiro AA, Vedal S, and Kaufman JD. 2015. Development of Long-term Spatiotemporal Models for Ambient Ozone in Six Metropolitan regions of the United States: the MESA Air Study. Atmospheric Environment, 123, 79-87. doi:10.1016/j.atmosenv.2015.10.042
  • Keller JP and Peng RD. 2019. Error in Estimating Area-Level Air Pollution Exposures for Epidemiology. Environmetrics, 30:8. doi:10.1002/env.2573

Measurement Error & Spatial Confounding

Two important challenges in air pollution epidemiology studies are exposure measurement error and unmeasured spatial confounding. Predicted exposures inherently have some error, and mitigating the impact of that error in downstream analyses is important. At the same time, unmeasured confounding can also bias health effect estimates due to the relationship between spatial exposures and unmeasured factors.

  • Keller JP and Szpiro AA. 2020. Selecting a Scale for Spatial Confounding Adjustment. 2020. Journal of the Royal Statistical Society, Series A, 183 Part 3:1121-1143. doi:10.1111/rssa.12556
  • Keller JP and Peng RD. 2019. Error in Estimating Area-Level Air Pollution Exposures for Epidemiology. Environmetrics, 30:8. doi:10.1002/env.2573
  • Keller JP, Chang HH, Strickland MJ, and Szpiro AA. 2017. Measurement Error Correction for Predicted Spatiotemporal Air Pollution Exposures. Epidemiology, 28, 338-345. doi:10.1097/EDE.0000000000000623

Health Effects of Outdoor Air Pollution Exposure

Quantifying the health effects of long-term air pollution exposure requires combining accurate exposure assessment, health outcomes, and other risk factor information. In collaborations with epidemiologistis and clinicians, we have identified adverse effects of air pollution on cardiovascular outcomes, allergic disease, and cancer outcomes.

  • Keet CA, Keller JP, and Peng RD. 2018. Long-term coarse PM is associated with asthma among children in Medicaid. American Journal of Respiratory and Critical Care Medicine, 197(6):737-746. doi:10.1164/rccm.201706-1267OC
  • White AJ, Keller JP, Zhao S, Carroll R, Kaufman JD, and Sandler DP. 2019. Air pollution, clustering of particulate matter components and breast cancer. Environmental Health Perspectives, 127:10. doi:10.1289/EHP5131
  • Keller JP, Larson TV, Austin E, Barr RG, Sheppard L, Vedal S, Kaufman JD, and Szpiro AA. 2018. Pollutant composition modification of the effect of air pollution on progression of coronary artery calcium: the Multi-Ethnic Study of Atherosclerosis. Environmental Epidemiology, 2(3):e024. doi:10.1097/EE9.0000000000000024
  • White AJ, Kresovich JK, Keller JP, Xu Z, Kaufman JD, Weinberg CR, Taylor JA, and Sandler DP. 2019. Air pollution, particulate matter composition and methylation-based biologic age. Environment International, 132. doi: 10.1016/j.envint.2019.105071

Household Air Pollution

Household air pollution (HAP), particularly from combustion sources such as cookstoves, presents a major health burden around the world. In collaboration with epidemiologists and exposure scientists, I work on methods for improving our ability to quantify health effects of HAP.

  • Keller JP, Katz J, Pokhrel AK, Bates MN, Tielsch J, and Zeger SL. A Hierarchical Model for Estimating the Exposure-Response Curve by Combining Multiple Studies of Acute Lower Respiratory Infections in Children and Household Fine Particulate Matter Air Pollution. In press. Environmental Epidemiology, 4(6):e119. doi:10.1097/EE9.0000000000000119
  • Benka-Coker ML, Young BN, Keller JP, Walker ES, Rajkumar S, Volckens J, Good N, Quinn C, L’Orange C, Weller ZD, Africano S, Osorto Pinel AB, Peel JL, and Clark ML. Impacts of the wood-burning Justa cookstove on fine particulate matter: a stepped-wedge randomized trial in rural Honduras. Science of the Total Environment In Press. DOI: 10.1016/j.scitotenv.2020.144369
  • Young BN, Peel JL, Benka-Coker ML, Rajkumar S, Walker ES, Brook RD, Nelson TL, Volckens J, L’Orange C, Good N, Quinn C, Keller JP, Weller ZD, Africano S, Osorto Pinel AB, Clark ML. 2019. Study protocol for a stepped-wedge randomized cookstove intervention in rural Honduras: Household air pollution and cardiometabolic health. BMC Public Health, 19:903. doi:10.1186/s12889-019-7214-2

Risk Factors for Allergic Disease

In collaboration with immunologists at Johns Hopkins Unviersity, we are examing risk factors for pediatric allergic disese in the US Medicaid cohort.

  • Keet CA, Keller JP, and Peng RD. 2018. Long-term coarse PM is associated with asthma among children in Medicaid. American Journal of Respiratory and Critical Care Medicine, 197(6):737-746. doi:10.1164/rccm.201706-1267OC
  • McGowan EC, Keller JP, Dellon E, Peng RD, and Keet CA. Prevalence and Geographic Distribution of Pediatric Eosinophilic Esophagitis in the 2012 US Medicaid Population. Journal of Allergy and Clinical Immunology-In Practice, 8(8):2796-2798.e4. doi:10.1016/j.jaip.2020.04.009
  • Dunlop JH, Keller JP, Peng RD, and Keet CA. The Effect of Season of Birth on Atopic Dermatitis and Food Allergy. Annals of Allergy, Asthma & Immunology, 125(2): 221-223.E2. doi:10.1016/j.anai.2020.04.034