IAQ industry professionals and concerned homeowners joined committee members from the American Society of Testing and Materials' (ASTM) Subcommittee D22.05 on Indoor Air for a workshop focusing on "Black Soot Phenomena." The workshop was held last month at the Rosen Centre Hotel in Orlando, Fla., and was co-chaired by Dr. Niren Nagda of ENERGEN Consulting Inc. and Dr. David Ensor of the Research Triangle Institute. There were approximately 70 attendees.

The purpose of the workshop was to, "assess the state of the art related to methodologies used for field and laboratory investigations," related to black soot phenomena, according to Nagda. The co-chairman also noted that the ASTM workshop format was less formal than a symposium, and that there would be no published papers or proceedings following the conclusion of the workshop. He stressed the fact that the ASTM is a voluntary standards development organization, and does not fund research.

In recent years, an increasing number of concerns related to the appearance of soot-like material in new or newly renovated homes and buildings have confounded homeowners and developers alike. According to anecdotal evidence, the problem seems to be especially prevalent in the southeast United States, prompting the ASTM to organize the workshop during its D22 Committee Meetings week.

Nagda went out of his way to let several exasperated homeowners know that concrete solutions for their concerns regarding the unexplained soot-like deposition in their homes would not be forthcoming on this day.

"The purpose of this workshop is to share understanding and review methodologies," related to black-soot phenomena, he said.

In his overview, Nagda defined the phenomena as, "any unexpected visible staining, deposition, ghosting or graying of interior surfaces." Illustrating how little is known for certain regarding the phenomena, Nagda pointed out that this "black soot" may be particulate or microbial in nature, is resistant to conventional cleaning methods and may have numerous possible sources. In light of this, many attendees favored the term "black residue" or "black particulate" to more accurately reflect those possible sources. Many in attendance felt the term soot was not appropriate because it implied the phenomena was related strictly to products of combustion such as candles.

Nagda's overview was followed by four presentations featuring high-profile IAQ professionals. First up was Ensor, as he discussed possible mechanisms to explain the "black soot" phenomena. Three possible mechanisms Ensor discussed were in place amplification, transport with deposition and adhesion enhancement. He quoted research by Northern European scientists that postulates "adhesion enhancement" as the process by which organic materials increase their surface adhesion capabilities (stickiness) in the presence of semi-volatile organics.

"Call Your Congressman"

Next up was the presentation by David Krause of Indoor Air Solutions Inc., regarding on-site methodologies used for Florida homes. Krause spoke passionately of the "tremendous need for research and standardization" of black soot sampling and on-site methodologies during investigations. He spoke of characterizing deposition patterns, source assessment (e.g. candles, diesel engines, fireplaces, & unvented heaters) and environmental parameters such as temperature, relative humidity, ventilation rate, electrostatic charging and surface characteristics.

He went on to address the assembled about particle assessment in terms of size, morphology, age and density. In one exchange with an attendee having health problems related to black soot in her home, Krause suggested she, "call her congressman" as one small step that could be made to help educate public officials on the importance of indoor environmental issues.

The final two presentations by Dan Cautley of ENERGEN Consulting Inc. and Lori Streit of Unified Engineering Inc., worked well paired together, after a short break in the workshop. The topics, "A protocol for on-site investigations" and "Techniques and results of laboratory analysis of black soot," demonstrated the multi-disciplinary approach by which the black soot phenomena needs to be addressed. Cautley's mantra of, "Be sure to include control samples!" during investigations was echoed by Streit in her comments regarding laboratory procedures. Streit also spoke of the fascinating technology that laboratories utilize in their analysis of black soot, including gas chromatograph/mass spectroscopy and scanning electron microscopes.

The presentations were followed by an question and answer session. The discussion centered on the need for more research and the development of specific research goals, the standardization of best practices for investigations and laboratory analysis, and the construction of coherent, standardized definitions of what exactly "black soot" refers to.