Health impact evaluations of water, sanitation and household air pollution interventions in low-income countries

Thomas Clasen Research Group

After practicing international corporate law for 20 years, I returned to school and obtained an MSc in control of infectious diseases and a PhD in environmental health from the London School of Hygiene and Tropical Medicine.  I joined the faculty of the LSHTM in 2004, and became Professor of Water, Sanitation and Health. I moved to the Rollins School of Public Health in 2013 as Professor of Environmental Health and Rose Salamone Gangarosa Chair of Sanitation and Safe Water.

I lead a group of researchers whose work consists mainly of health impact evaluations of water, sanitation and household air pollution interventions in low-income countries.  Publications include more than 15 RCTs in Latin America, Africa and South Asia; Cochrane reviews of water quality and sanitation interventions to prevent diarrhoeal disease and enteric infection; methods papers on improving the rigor of evaluating environmental health interventions; cost and cost-effectiveness analyses; and policy analyses of global environmental health initiatives.

Current field research includes an evaluation of rural water and sanitation programs in Orissa; an RCT to assess the impact of arsenic water filters in West Bengal; a health impact evaluation of a large-scale deployment of water filters and improved cook-stoves in Western Province, Rwanda, a trial to evaluate household air filters in New Delhi, and a multi-center study aimed at assessing the impact of a liquefied petroleum gas (LPG) cooking stove intervention on health in India, Guatemala, Peru and Rwanda. I serve as an advisor to the World Health Organization in developing the first set of Guidelines on Sanitation and Health.!TCLASEN


  • Evaluation
  • Global Health
  • Health Outcomes
  • Infectious Disease
  • Safe Water and Sanitation
  • Air Pollution


  • JD, 1981, Georgetown University Law Center
  • MSc, 2002, London School of Hygiene & Tropical Medicine
  • PhD, 2006, University of London


  • EH 570: Env/Occ Hlth Policy
  • EH 571: GEH Policy:Power,Sci.&Justice
  • EHS 798R: Pre-candidacy Research
  • EHS 799R: Dissertation Research