Judges’ Queries and Presenter’s Replies

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Presentation Discussion

  • Icon for: Teresa Wang

    Teresa Wang

    Trainee
    May 21, 2012 | 07:29 p.m.

    What exactly does adding (DCFH) do?

    Does ROS have any association with cigarette smoke (eg in the homes that you monitored?) Thanks!

  • Icon for: Shahana Khurshid

    Shahana Khurshid

    Presenter
    May 22, 2012 | 10:18 p.m.

    DCFH is a non-fluorescent organic compound. It contains 4 rings. Upon exposure to ROS in the presence of horseradish peroxidase, DCFH gets oxidized to the fluorescent compound DCF (with the removal of 2 hydrogen ions from DCFH). The intensity of fluorescence can be used to determine the concentration of ROS with the help of a standard curve with hydrogen peroxide.

    Cigarette smoke contains a lot of ROS! In a study comparing the concentration of ROS on fumes collected from on-road vehicles, an ambient outdoor location, an indoor location, cooking, burning incense, and cigarette smoke, the highest concentration of ROS was found in cigarette smoke (See et al., 2007). Huang et al. (2005) has also assessed the concentration of ROS in cigarette smoke.

    All the homes (and other sites) that I sampled at were non-smoking establishments.

  • Icon for: Teresa Wang

    Teresa Wang

    Trainee
    May 23, 2012 | 03:42 p.m.

    Thank you, Shahana!

  • Icon for: Dori Eubank

    Dori Eubank

    Coordinator
    May 22, 2012 | 02:34 p.m.

    Great video on very interesting research!

  • Icon for: Shahana Khurshid

    Shahana Khurshid

    Presenter
    May 23, 2012 | 04:53 p.m.

    Thanks for viewing it!

  • Icon for: Annie Aigster

    Annie Aigster

    Coordinator
    May 22, 2012 | 04:01 p.m.

    Great topic. I enjoyed your video as it was highly interactive. Looking at your data on the ROS in the institutional buildings, do you know why the ROS were so high on one day (Jan 27) compared to the other days? Thanks.

  • Icon for: Shahana Khurshid

    Shahana Khurshid

    Presenter
    May 23, 2012 | 06:48 p.m.

    One of the judges had asked me a similar question! The concentration of ROS depends on a variety of factors: ozone concentration, intensity of photochemical reactions, and temperature are important factors, but there are several other contributing factors. In particular, on Jan 27, the outdoor concentration of PM2.5 (6 µg/m3) was relatively higher than usual, which may partly explain the high concentration of ROS. Gas-phase ROS can deposit onto particles increasing the concentration of ROS on these particles.

  • Icon for: Mark Jackson

    Mark Jackson

    Associate
    May 22, 2012 | 07:54 p.m.

    Woudl be fascinating to look at how ROS can be effectively controlled to some deminimus level using high efficiency filtration. Would also be interesting to see if there is some threshold of ROS below which health impacts are minimal.

  • Icon for: Shahana Khurshid

    Shahana Khurshid

    Presenter
    May 23, 2012 | 06:47 p.m.

    Definitely! I plan to look into control strategies for indoor ROS once I have gathered and integrated the results from the sampling data. Furthermore, I am interested in exploring the relationship between the level of ROS and the associated health effects as one of my future research projects.

  • Further posting is closed as the competition has ended.

Icon for: Shahana Khurshid

SHAHANA KHURSHID

University of Texas at Austin
Years in Grad School: 3

What's in the air? The prevalence and health effects of particulate reactive oxygen species.

The objective of my dissertation research is to understand the fundamental health effects of reactive oxygen species (ROS) and the principle parameters that influence the indoor and outdoor concentrations of ROS. ROS are an important class of secondary air pollutants generated from photochemical reactions in outdoor air and ozone-initiated reactions in indoor air. While ROS are produced naturally in the body to defend against foreign organisms, exposure to excessive levels of ROS can induce cell injury and has been implicated in many pulmonary diseases. In this research, the concentration of ROS on respirable particles was assessed in residential, institutional and retail buildings. The data indicates that the concentration of ROS inside buildings can be higher than the outdoor ROS concentration, and on average it is 1.8 times higher. High indoor ROS concentrations can have important implications on our health, given the large proportion of time we spend indoors. Furthermore, an in vitro exposure model was used to assess the inflammatory response of human lung cells to products from ozone-initiated reactions. It was found that lung cells produce higher levels of inflammatory proteins upon exposure to a mixture of d-limonene and ozone (used as a model system to generate oxygenated organic species). Overall, this research highlights the prevalence of products from ozone-initiated reactions in the environments in which we spend most of our time and the importance of reducing our exposure to these pollutants.