The current national ambient air quality standards for particulate matter (PM) are based on particulate mass. Although epidemiological research conducted in the last few decades have associated PM mass with both respiratory and cardiovascular diseases, the heterogeneous and inconsistent nature of these associations suggests that not all components of PM are equally toxic. The capability of ambient particles to generate reactive oxygen species (ROS), conveniently called the oxidative potential is proposed as a better metric for relating the PM pollution with health effects.

In this talk, I will present our work on the measurement of oxidative potential of ambient PM from different geographical locations of the United States, i.e. western, southeastern and midwest US. The core objective of this work was to identify the components of ambient PM, which are most responsible for inducing the ROS generation. The role of organic compounds in the ROS activity of PM was assessed by their removal using thermodenuder and solid phase extraction technique, while the contribution of metals was quantified by chelation technique. A class of water-soluble organic compounds known as humic-like substances or HULIS, and transition metals particularly Fe, Cu and Mn were identified as the major species driving the ROS generation mechanism in ambient particles. However, our work shows that there are strong synergistic and antagonistic interactions among the HULIS components and transition metals. Further studies in this direction should help to develop the useful insights on the origin of PM toxicity leading to a better assessment of the human health effects of ambient particulate pollution.

Bio: Dr. Verma is an assistant professor at the University of Illinois Urbana Champaign and his current work is focused on assessing the health impacts of ambient air pollutants. In his 10 years of research career, he has published more than 25 peer-reviewed articles in highly ranked journals and has presented his work in at least 50 seminars/meetings and conferences, including several invited talks. He is the current president of the Health related Aerosol working group at AAAR and has earned numerous awards and recognitions for his work including the invited chair for special symposiums/sessions on Air Pollution and Health in the annual AAAR conferences (2014, 2015, 2017 and 2018).