Dr. Walker is an environmental health scientist with over 35 years of experience spanning private, academic and non-profit sectors. She retired at the end of 2020 from her position as Principal scientist at the Health Effects Institute, an independent air pollution health effects research organization in Boston MA. For the last 5 years of her tenure, she lead HEI’s global programs which have included: development the State of Global Air website and publication of its annual reports in collaboration with the Global Burden of Disease project at the Institute for Health Metrics and Evaluation at the University of Washington; studies of the burden of disease from major air pollution sources (GBD MAPS) globally and in the major countries of China and India; analyses of air quality and health impacts of shipping in the Shanghai/Yangtze River Delta, China; and estimation of the contribution of household air pollution to ambient air quality in Ghana, Africa.
Prior to taking on HEI’s global program, Dr. Walker led expert panel reviews of 1) the Diesel Exhaust in Miners study and its suitability for use in quantitative risk assessment and 2) the state of the science regarding the measurement of ultrafine particles and their effects on health. She has also served as the senior staff scientist for numerous HEI-funded research studies — multi-center, multi-city time series study of air pollution and health in Europe and North America (APHENA) and in South America (ESCALA), accountability studies of London’s congestion charging scheme and low emission zones; multi-center U.S. study of the effects on health of particulate matter composition and gaseous co-pollutants (NPACT), and various research studies on the development of statistical methods for multi-pollutant analysis, accountability studies, and causal inference, among others. Walker has also represented HEI science in numerous national and international venues, including the U.S. Environmental Protection Agency, Institute for Health Metrics and Evaluation, European Commission, and World Health Organization. Prior to joining HEI, Dr. Walker spent over 20 years in the private and academic sectors in the application and evaluation of public health risk assessment, including characterization of uncertainty, to support environmental decisions. Dr. Walker holds a M.S. and Sc.D. in Environmental Health Sciences from the Harvard TH Chan School of Public Health.