Icon for: Shahana Khurshid


University of Texas at Austin
Years in Grad School: 3

Judges’ Queries and Presenter’s Replies

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Presentation Discussion
  • 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

    Lead 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.

  • May 23, 2012 | 03:42 p.m.

    Thank you, Shahana!

  • Icon for: Dori Eubank

    Dori Eubank

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

    Great video on very interesting research!

  • Icon for: Shahana Khurshid

    Shahana Khurshid

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

    Thanks for viewing it!

  • Icon for: Annie Aigster

    Annie Aigster

    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

    Lead 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

    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

    Lead 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.

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