Head of Center for Atmospheric Research, Dean of School of Environmental Sciences. He led the development of instrumentation for the measurement of black carbon and other light absorbing carbonaceous aerosols. His current focus is on reference methods for the measurement of the aerosol absorption coefficient, in the past he led the development of the most globally used filter-absorption photometer. His current research includes quantifying the role of aerosols in climate change; source apportionment of particulate matter for local studies and in context of long-range transport; airborne measurements of aerosols with small aircraft and balloons; and validation of satellite products.
He served as a member of the United Nations ECE expert group on Black Carbon. He is recipient of the national Puh Award for Excellence in Innovation. He was the director and scientific director of SMEs. He led international and national projects; engaged in outreach with NGOs and general public on climate and air quality.