Toxicological Chraracteristics of Particulate Matter in an Urban Environment and Their Linkage to the Source-Specified Constituents

Speaker: Vishal Verma, Environmental Engineering Ph.D. Candidate

Talk Title: Oral Dissertation Defense

Abstract:
Airborne particulate matter originates from two broad categories of sources: primary and secondary. Primary particles are directly emitted from combustion sources, including heavy and light duty vehicles, wood smoke, industries and construction activity. In the presence of various atmospheric oxidants, primary particles may undergo photochemical processing yielding secondary particles with distinctly different physical and chemical characteristics compared to their precursor species. Numerous epidemiological studies have linked the particulate matter (PM) to various adverse health effects, including premature deaths, and respiratory and cardiovascular diseases. Despite commendable progress in particle-related toxicological research for the last few decades, the exact mechanisms by which PM inflicts health injuries are still largely unknown and constitute a subject of great interest and very active research for the scientific community. The biological reaction(s) by which PM exposure causes proinflammatory effects, and the sensitivity of inflammation and subsequent toxicity to variations in PM composition remain to be fully understood.
The primary objective of this work is to determine the toxicological characteristics of particulate matter in an urban environment and their linkages to the source-specific particle constituents. This objective has been carried out by evaluating the oxidative potential of particles collected from various sources such as exhaust tail pipe of the heavy-duty diesel vehicles, wood-smoke and ambient particles in segregation to their primary and secondary sources. Both cell-free and cell-based assays were used to evaluate the oxidative potential of the collected particles. In addition, the physico-chemical characteristics of the sampled particles, such as particle number distribution and concentration, elemental and organic carbon, water soluble organic carbon, water soluble elements, inorganic ions and organic species were also analyzed. The association of PM chemical constituents with their oxidative characteristics was investigated by mechanistic (physicochemical segregation of PM constituents) and statistical (bivariate and multivariate regression) techniques. The study offers a novel and informative perspective on the relationship between composition and sources of atmospheric particles to their relative toxicity potential. This is useful in elucidating the health risks related to the PM exposure from different sources and ultimately in promulgating the effective control strategies to protect public health.

Audiences: Everyone Is Invited

Contact: Evangeline Reyes