Kai-Chung gave a presentation on his recent work regarding the reconstruction of true CO levels from readings of a diffusion CO sampler with a slow response time. A report on this work is also forthcoming. The powerpoint presentation is attached.

If you have not been able to access the Exposure Science website because you have forgotten your password. There is an easy way to set a new one!

Simply go to the following URL and enter your email address:

http://exposurescience.org/user/password

After clicking on "Email new password", an email will be sent to you that tells you how to gain access to your account and make a new password.

If you are still having problems, please send me an email.

You can use the contact form: http://exposurescience.org/contact

I reworked one of my data processing scripts written in R to automatically process real-time SidePak aerosol data. You may recall I wrote the script originally for CO data processing.

With this script it is possible to very quickly create an R dataframe containing all of the real-time data present in a given directory. Attached is a ZIP file containing the new R processing scripts.

Neil, Wayne, and Kai-Chung visited the San Pablo Lytton casino in San Pablo, CA on January 12, 2008. They were able to measure aerosol data, casino dimensions, and nonsmoker/smoker counts. The visit was a success and informed protocols that can be used in our subsequent casino surveys.

Attached to this post is a detailed write-up of the visit, including the protocols used and the results.

All data from the visit have been uploaded to the archive server at the following FTP site:

domain: exposurescience.org
username: datastore

I gave a presentation to the projectRIDE Bay Area tobacco-free community group (http://www.projectride.net/home.html). The group's members are African American, Latino, and Asian young men who are hotrod enthusiasts. They build vehicles and show them at tobacco-free events around the state and country. The group is sponsored by the state of California's Proposition 99 (same funding source as the TRDRP, who fund our own project). The tobacco industry targets men in this age group and special interest (custom cars).

Mark Nicas, adjunct professor of Environmental Health at UC Berkeley, and his graduate student Rachael Jones are currently pursuing indoor pollutant dispersion experiments similar to those we are pursuing at Stanford. They are measuring and modeling particle transport and deposition in room-sized chamber following the release of mono-dispersed aerosol. Bill Nazaroff is also one of the co-Invesigators.

I have written a program for Linux called "SidePak LaBraT" that is able to simultaneously plot and save real-time SidePak aerosol data from multiple SidePak units. It seems currently impossible to connect multiple SidePaks to a single Windows computer, so this software is Linux-only. I've spoken to the folks at TSI and FTDI (makers of the USB/Serial chip) and there seems no way for the Windows drivers to handle multiple SidePaks. But Linux has no problem :-).

"SidePak Buddy" is software for the Linux and Windows platforms that plots and saves real-time aerosol levels measured by a TSI SidePak Aerosol Monitor. This software is meant to be a user-friendly way for both technical and non-technical people to see the immediate impact of a source of particulate matter on air quality.

I have recently used this software to demonstrate the levels of real-time particles that occur in an automobile with an active smoker present (see http://latimes.com/smoking).

This updated version of "SidePak Buddy" (Version 1.2) has the following features:

http://BurningIssues.org
For a period of more than 10 years from 1994 to the present, Dr. Wayne Ott of the Statistics Department, Stanford University measured indoor and outdoor particulate polycyclic aromatic hydrocarbons (PPAH) levels in his residential neighborhood in Redwood City, CA.

To predict the proximity effect, I have applied the "Markov I" stochastic model of Nicas (2001) to characterize the dispersion of air pollution from a "puff" release in a room that has dimensions of 10.7 x 7 x 2.6 meters (L x W x H). The model treats the dispersion of emitted particles as a Markov Chain process, where each particle moves by a series of "random walks" due to turbulent diffusion. The value for the turbulent diffusion coefficient, D, was set at 0.04 m2/sec.

In applying the model, I used 6 receptor positions located 0.5, 1, 1.5, 2, 2.5, and 3 meters away from the source in the horizontal direction. The air exchange rate for the simulation was 0.5 ach, which is typical for a residential location.

Attached to this post are two plots showing the results of the simulation:

1. A "Concentration versus Time" plot showing the concentration time series at each of the receptor points (note the y axis is on a log scale) for a period of 15 minutes after the release.

2. A "Average Concentration versus Distance" plot showing the proximity effect of 1-minute average concentration as a function of distance from the source. The 1-min average was take during the minute just after the release occurred.

These plots are in broad agreement with prior work showing that (A) air pollution from a "puff" release generally mixes thoroughly in the room of release within 5 to 10 minutes after release, and (B) that the proximity effect is generally an f(x) = 1/x function of Concentration vs. Distance.

This modeling approach can be expanded to include advection (air currents), obstructions, inlet and outlet flows, particle deposition, and reflection.

Note: Also attached to this post is the R source code used to run the Nicas model.

I've come across two webpages that contain online calculators, one for estimating the natural or mixed-mode ventilation rate of an arbitrary building:

http://phpaida.veetech.org.uk/phpaida.php

And one for estimating the ventilation rate of a building from steady-state CO2 measurements and occupancy level:

http://phpco2.veetech.org.uk/phpco2.php

In my research into prior work on indoor air pollutant dispersion, I have come across two paper that present valuable data relevant to our own work on the proximity effect and room mixing.

A paper by Drivas et al (Indoor Air. 1996; 6(4):271–277) applies a form of the atmospheric diffusion equation:

Modeling Indoor Air Exposure from Short-Term Point Source Releases. We have developed a simplified analytical indoor air model that describes the concentrations as a function of position and time in a room following a short-term release of airborne particles or gases. The indoor dispersion model considers the two main physical processes of (1) point-source dispersion with reflection from all walls and (2) the general concentration decay in a room due to room ventilation and surface deposition of pollutants. Comparison of model predictions with experimental indoor measurements conducted by other researchers showed excellent agreement. This model should prove useful for human-health risk estimations in which the inhalation dose resulting from an indoor, short-term release of a contaminant needs to be calculated.

Nicas builds from the work of Drivas et al. and uses a "Markov" probabilistic approach, incorporating the effects of advection (AIHAJ. 2001 Mar-Apr;62(2):149-58):

Modeling turbulent diffusion and advection of indoor air contaminants by Markov chains. Turbulent eddy diffusion models are used to describe a continuous concentration gradient with distance from an in-room contaminant emission source. A refined diffusion model termed the Drivas model also accounts for contaminant reflection by wall surfaces and partially accounts for removal by exhaust air. This article develops two models based on Markov chains to describe indoor air contaminant dispersion by turbulent diffusion and advection, and removal by the exhaust airflow. Markov model I is equivalent to the Drivas model and is computationally simple. Markov model II can provide more realism by accounting for the locations of air inlets and outlets, advective flow patterns, in-room reflective surfaces, and contaminant removal mechanisms at specific room positions. The price paid for this greater realism is greater computational complexity. Both Markov models are explicitly probabilistic and estimate the expected concentration values at given room positions.

I have created an electronic repository for PDF versions of papers that may be of importance to our work. It is located at the main server that I created before:

domain: exposurescience.org
username: datastore
directory: Articles_PDFs

If you have forgotten the password please contact me. (Note: It begins with "s").

I will continue to add papers to this repository as I obtain them.

Attached to this post is an updated list of references that may be of interest in our indoor air dispersion experiments (proximity effect, mixing, microplumes). The key players for CFD include folks at the Lawrence Berkeley Lab (Gadgil et al.). Mark Nicas at UC Berkeley has contributed some interesting probabilistic work using Markov Chains, apparently building off of work by Drivas et al. I've included a column in the table for comments on each paper. As different folks read the papers, they can add their comments to this document.

I've continued work on an MS Windows application to facilitate retrieving and viewing real-time aerosol concentrations from a TSI SidePak monitor. Attached is a ZIP file containing the Windows EXE file, which has been tested on Windows XP, as well as the complete Perl/Tk source code (in a compressed ZIP file). This is a pre-release version and is intended to be tested in a limited group before being released publicly. Please use it, mangle it, and tell me all about it.... Note: I've dubbed this version the "SidePak Buddy" since "tkSidePakGetWin32" was a little cryptic :-).

I finished a simple computer program tested on Windows XP that you can easily use to view and save real-time aerosol concentrations from a USB-connected TSI SidePak aerosol monitor. Simply unzip the attached file and copy the Windows EXE file ("tkSidePakGet.exe") to your desktop or anywhere else on your hard drive.

Double-clicking on the blue SidePak icon will launch a terminal window and a plotting window in which SidePak concentration values will immediately start appearing on a stripchart, 1 every second. The values are also automatically saved in a text file named sidepackoutput.csv (by default). The File menu contains items for starting and stopping the stripchart and for saving the current plot as a PostScript file.

Neil Klepeis was interviewed by Marrecca Fiore of FoxNews.Com regarding the recent Stanford study on outdoor tobacco smoke. An article resulting from the interview appeared on the Fox News website on November 15. She did a pretty good job with some of the technical discussion, I thought. She also gave a link to a WikiPedia.Org article showing the smoking bans currently active in different states in the U.S.

We lost our electricity last night (Nov 10) and proceeded to light many candles throughout the house. 6 in the kitchen, 4 in the living room, and 3-4 in the bedroom area. These were both the large scented candle variety and the tall candlestick variety. This photo shows the time series of aerosol as measured by the Sidepak using a 0.32 calibration factor. As with the hookah (see earlier post) the measured mass emissions seem very high and need to be confirmed by lab calibration experiments.

As a test of the Sidepak in field locations and also to gather some pilot data for hookah emissions, Wayne Ott, Neil Klepeis, and friends visited a hookah lounge on November 8, 2007. This is a plot of the particle concentrations as measured by the SidePak monitor with the calibration factor set at 0.32. Up to 4 or 5 hookahs were active at a time. Note: A hookah is a mid-Eastern water pipe that heats a 25% tobacco/fruit mixture. Attached is the log sheet from the visit.

I have just finished working up a small Perl computer script that can communicate with a SidePak aerosol monitor over a Windows COM port, gathering data in 1-sec intervals. It gathers data every second and writes the returned values to a text file along with a time and date stamp. See the attached files for the script ('SidePakGetWin32.pl') and an example of the output written to a file ('temp.txt').

Just in case you are one of the uninitiated in the wonders of the SidePak :), you can get more info at TSI.

This image shows the maximal number of stands needed for all symmetrical configurations, ranging from 2 arms (180 deg arcs) through 8 arms (45 degree arcs). It assumes that we will not have more than 4 stands in a given direction. Thus, since 8 arms is likely the most we would ever consider, the maximum number of stands we would ever need is 32. The minimum would likely be 8 corresponding to the two arm case.

Attached is a prototype script "process_monitors.Rf", written in R, that can be used to automatically process real-time data files, e.g., for carbon monoxide (CO) or particles. By default it treats ASCII files for CO created by the Langan DataBear. It can be run by creating an R shell script containing the following (see second attached file "processCO.R"):

eval(parse(file="~/SCRIPTS/process_monitors.Rf"))
process.monitors("TEST")

Note: The above assumes that the script is located in the SCRIPTS directory of the top-level directory of the user's account.

Attached is a list of possible research questions that might be answered using a neutral-buoyancy bubble generator.

Attached is a file containing a list of potentially valuable references for our study of indoor air pollutant mixing and dispersion

Viviana and Neil made a visit to a casino near Sacramento to gather some initial data for piloting our casino survey. Attached is a short report describing the results of this monitoring visit.

Attached to this post is a draft data management protocol for organizing the data sets that result from our real-time monitoring experiments and surveys.

Attached to this post is a Word document listing hypotheses and research questions related to our indoor and outdoor proximity experiments.

Neil Klepeis attended the National Conference on Tobacco or Health, held in Minneapolis, MN. He spoke with many tobacco control advocates and health department workers, many of whom have used our work on outdoor and in-vehicle tobacco smoke levels in their program materials. Dr. Klepeis also attended a pre-meeting dinner where several scientists and advocates discussed the issue of tobacco smoking bans in multi-unit housing. James Repace, Mark Travers, Dave Bohac, and Martha Hewitt represented the scientific side.

Wayne Ott and Neil Klepeis met with Matthew Korhman, a Stanford professor of Anthropology, who has an interest in international tobacco control efforts. There is the possibility of collaboration with Prof. Kohrman regarding the use of real-time pollution monitoring techniques to disclose tobacco smoke levels in hospitals and other locations.

Neil Klepeis gave an interview with a reporter for the Bay City News Services in relation to the new ban on outdoor smoking in Farmer's Markets: "The Pacific Coast Farmers' Market Association recently banned smoking inside its markets and within 30 feet of each market's perimeter." A few quotes from Klepeis appeared in an article which was carried by many small Bay Area daily and weekly newspapers:

Neil Klepeis gave an interview to Ruthann Richter about an outdoor smoking ban at the Stanford University School of Medicine. An article appeared in the Stanford News Report. Dr. Klepeis discussed the recent study on outdoor tobacco smoke and how much exposure might occur at a table or bench near smokers.

Neil Klepeis gave an interview to Bottom Line / Health magazine on exposure to outdoor tobacco smoke. A small blurb appeared in a Summer 2007 issue.

Dr. Klepeis gave an interview to Health Magazine and a blurb has appeared in the October 2007 issue, given below:

"Keep your distance from outdoor smokers"

Neil Klepeis gave a lecture at the California Clean Air Project's (CCAP) training in Sacramento, CA located at the Sierra Health Foundation at 1321 Garden Highway. CCAP is sponsored by the state of California's Department of Health, Tobacco Control Section (Joanne Wellman, John Francis). The attendees were generally health advocates, staff of county and city health departments, and other "tobacco control" folks. Dr. Klepeis discussed recent monitoring studies of outdoor and in-vehicle secondhand smoke and fielded a number of questions about the monitoring and the study results.

Neil Klepeis was interviewed by Andre Picard of the Canadian Globe and Mail for a short news article on the outdoor tobacco smoke study entitled Outdoor patios as smoky as bars.

Neil Klepeis was interviewed by Liz Szabo of USA Today regarding the just-published article on outdoor tobacco smoke. The article entitled Study:shows Outdoor smoke gets in your lungs generated a lot of comments on the USA Today website, both pro and anti-smoking.

Neil Klepeis was interviewed live on Australian Broadcasting Corporation's (ABC) Station 666 Breakfast Radio Show with Ross Solly, which is out of Canberra, Australia. The topic was mostly the new article on secondhand smoke in automobiles. The announcer also asked questions about "exposure science" in general, and Neil proceeded to wax on the topic of how indoor air pollution can sometimes be much greater than the much more regulated outdoor ambient pollution.

Wayne Ott and Neil Klepeis were interviewed by David Cohen of the New Scientist Magazine, which is based in the UK. Topic discussed included the new study on secondhand smoke in cars, as well as a lot of discussion about the outdoor tobacco smoke study. David Cohen was interested in preparing an illustration showing the "circles of exposure" that could occur in outdoor areas near smokers. We also discussed quite a bit about the general area of Exposure Analysis, showing David the new book.

Neil Klepeis presented the results of the outdoor tobacco smoke study as part of a webinar (web-based seminar) sponsored by the California Tobacco Control Section (Dept. of Health Services), hosted by John Francis, MPH. There were 80+ people that participated in the call by telephone and by logging into a webserver where Neil presented about 35 slides. Topics included a brief rundown of the particle monitoring devices, a description of the outdoor study, and a discussion of how these results could be applied for use in Tobacco Control efforts.

Neil Klepeis was interviewed by Jim Bell of KCBS (SF Bay Area Radio Station) about the article on secondhand smoke in cars. The interview will be broadcast the following Sunday. Topics discussed included the basic findings of the study, the type of pollutant measured, comparisons to indoor levels in bars, definition of air change rate, bottom line for findings, how we want our results to be used.