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A cross-divisional department spanning

Research Program Gurumurthy Ramachandran, PhD

Meet Ram's Team...

Gurumurthy 'Ram' Ramachandran, PhD

rams lab

Ram is Professor and Co-deputy Chair of the Department of Environmental Health and Engineering, and Director of the Johns Hopkins Education and Research Center for Occupational Safety and Health funded by the National Institute for Occupational Safety and Health (NIOSH). He has conducted research in various areas relating to human exposure assessment in occupational, residential, and outdoor settings. His research has included the development of occupational exposure assessment strategies for airborne contaminants. He has conducted pioneering studies in occupational hygiene decision-making that synthesizes mathematical exposure models, monitoring data, and probabilistic expert judgment within a Bayesian framework. He has led or participated in multi-disciplinary teams engaged in numerous community and occupational exposure assessment and epidemiological studies in the US, India, and Canada, and Bangladesh, and collaborates on epidemiological studies in Bangladesh relating to cookstove emissions, designing exposure chambers for animal studies, and lung dosimetry modeling. He is also co-leading the Exposome Collaborative at Johns Hopkins University

Kelsey Babik, MPH
PhD Candidate


Kelsey, originally from Johnstown, PA, graduated from the University of Pittsburgh in 2012 BS in Molecular Biology and a minor in US History. Realizing she was unable to find full-time employment with these credentials in the middle of the Great Recession, she spent a few years teaching SAT-prep classes, nannying, and spending plenty of time at the beach. Kelsey returned to school to pursue an MPH in environmental health from the Maryland Institute of Applied Environmental Health and graduated in 2015. Following her MPH, she worked for NIOSH and in the pharmaceutical industry as an industrial hygienist before deciding to pursue a PhD in exposure assessment. She joined the Department of Environmental Health and Engineering in 2018 and is currently a PhD student in the Exposure Sciences and Environmental Epidemiology track. Her research currently focuses on Markov modeling to predict exposures to nanomaterials in occupational settings. When not in the lab, Kelsey enjoys sleeping, reading, hanging out with her dog and fiancé (not necessarily in that order), and spending time with her family.


emma cogan

Emma Cogan, MPH '18
PhD Candidate

Emma Moynihan (née Cogan) is a Maryland native and received her BA in History from Loyola University Maryland. She received her MPH at the Johns Hopkins Bloomberg School of Public Health in 2018, with a concentration in Global Environmental Sustainability and Health. Like many of her colleagues, Emma is concerned about the public health impacts of climate change. Her research combines mathematical modeling, spatial statistics, exposure assessment, and environmental epidemiology to evaluate these impacts on the food system and occupational health. When not in the lab, Emma tries to avoid being scratched by her two cats, who really do love her deep down.




Melissa Seaton, MPH
PhD Candidate

Melissa was born and raised in Detroit, Michigan. She holds a BS in Environmental Science from the University of Michigan and a MS in Occupational Hygiene from the Harvard School of Public Health. She is currently a PhD candidate in the Exposure Sciences and Environmental Epidemiology track within the Department of Environmental Health and Engineering at Johns Hopkins Bloomberg School of Public Health. Melissa has worked as an industrial hygienist at the National Institute for Occupational Safety and Health for seven years, where she develops guidance and recommendations for chemical exposures in the workplace. Melissa's doctoral research is focused on microbial exposures, and she is particularly interested in developing mathematical models to gain a better understanding of how workers are exposed infectious diseases. Outside of her studies, Melissa enjoys traveling, biking, and yoga. 


Nima Afshar-Mohajer, PhD
Postdoctoral Fellow

Afshar-Mohajer received his PhD degree from Department of Environmental Engineering Sciences of the University of Florida; and his M.Sc. and B.Sc. from Sharif University of Technology in Tehran, Iran. His previous studies involved characterization and control of airborne particulate matter, PAHs and VOCs in different environments from occupational setting of a 3D printing lab to the lunar atmosphere. His current research includes characterization of in-vitro and in-vivo exposure systems to study the health impact of inhaling ambient PM2.5, oily marine aerosol, and cigarette smoke. He is also performing particle dosimetry modeling in the human respiratory system. His personal interests include watching movies, running and playing badminton.



Darpan Das, PhD
Postdoctoral Fellow

Darpan holds a PhD degree in Environmental Engineering from Indian Institute of Technology Bombay, India. During his PhD degree he worked on several aspects of clean cooking. His research area was focused on characterization of emissions from coal cookstoves and the possible mitigation strategies- Fuel Processing and Ventilation. His current research includes aerosol exposure modeling in different laboratory and field settings. He is also performing experimental and modeling-based studies on low-cost sensor and drones for air quality monitoring. His research also includes characterization of in-vitro and in-vivo exposure systems to study the health impact of inhaling ambient PM2.5 and cigarette smoke. When not in the lab, Darpan enjoys cooking, playing video games and going for hikes.





Yuan Shao, PhD
Postdoctoral Fellow

Yuan is a NIEHS T32 postdoctoral fellow in the Department of Environmental Health and Engineering in the Johns Hopkins Bloomberg School of Public Health. He is now co-supervised by Dr. Ramachandran and Dr. Ana Rule. Since joining Ram’s lab, Yuan has actively participated in and lead several ongoing research projects including a NIOSH pilot study grant, awarded to him in 2018, which considers the feasibility of computed tomographic reconstruction of spatial distribution of aerosols in laboratory and field settings with applications in hazardous sites. Yuan is an active Certified Industrial Hygienist (CIH) from American Board of Industrial Hygiene and holds an MS in Industrial Hygiene, and a PhD in Environmental Health Sciences (major) and Epidemiology (minor) both from the University of Minnesota, Twin Cities. His dissertation, co-supervised by Dr. Ramachandran and Dr. Alexander, was focused on reconstructing the historical exposure profiles for the workers in the Minnesota taconite iron mining industry, and assessing the association between these exposures and the workers’ respiratory diseases. When not in the lab, Yuan enjoys spending time his son, chatting with friends and watching Houston Rockets NBA games.