Volatile Organic Compounds (Siloxanes) Emitted by Engineering Students.

[NNadir]

A recent study published in the current issue of Environmental Science Technology has found that engineering students emit volatile organic compounds. Siloxanes Are the Most Abundant Volatile Organic Compound Emitted from Engineering Students in a Classroom (Environ. Sci. Technol. Lett., 2015, 2 (11), pp 303–307)

From the text:

Measurements were taken in a normally functioning classroom at the University of California, Berkeley, CA. The room volume is 670 m3, and its single-pass mechanical ventilation system operates from 8:00 to 20:45. The mechanical ventilation system provides an air-exchange rate of 5 ± 0.5 h?1 during operation. Outdoor air infiltration can be neglected because the classroom
has no windows or exterior doors. During classes, the two interior doors are generally closed. Additional characteristics of the
classroom have been described elsewhere.20 The occupant number and VOC and CO2 concentrations in the classroom were continuously monitored with high time resolution for five weekdays (one Tuesday, two Wednesdays, and twoThursdays). An observer recorded minute-by-minute occupancy and remained in the classroom during the whole daytime sampling period. For each class, there was a “stable” period during which the number of room occupants (N̅ remained relatively constant; N̅ equaled or exceeded 17 occupants for each of the 19 stable class sessions on the five monitored days. Each class session was taught by a faculty member from the Department of Civil and Environmental Engineering, and the classroom occupants were predominately engineering students.

Sampling was conducted by drawing air through a three-way Teflon solenoid valve, with switching between the supply air duct and the classroom air every 5 min. An in-line PTFE membrane filter was deployed in front of the instrument inlet to remove particulate matter from the sampled air. The classroom air sampling inlet was situated at the back of the room, two meters above the floor. Previous studies provide strong evidence to support our assumption that the room air was well mixed during times of occupancy.20 Supply air was sampled by inserting the 0.6 cm (1/4 in.) Teflon sampling tube through the ceiling diffuser into the air duct.

The air was analyzed by Proton Transfer Reaction Time-of-Flight Mass Spectroscopy (PTR-TOF-MS).

It was found that the engineering students mostly emit "D5" decamethylcyclopentasiloxane. These classes of cyclosiloxanes are commonly found in personal care products like deodorants, and some creams and the like. Recently, without any clear determination, there has been some suspicion about the health effects and environmental fates of some of these compounds - personal care product constituents are routinely detected throughout the environment, particularly in water supplies.

There was no information about emissions from theater arts students, English majors, French history graduate students, or students majoring in football and other related super important academic work in the athletics department. I suspect nobody really wants to know what chemistry students emit.

You can wait a whole month or more for a paper that's this much fun.

Have a nice evening.

[Awknid]

1. But I'd love to know what Chemistry students emit! LOL

[NNadir]

2. During my early career, I was clearly emitting alkylated selenophenols. My future wife...

...told me that one of the reasons that she was reluctant to respond to my advances (until the project changed) was that...that...smell, what the hell was that stuff anyway?

They were really interesting compounds, these sterically hindered selenophenols, inasmuch they seemed to diffuse readily through heavy gloves. While it possible to oxidize many thiols, including phenolic thiols, nothing would do away with these compounds. Your hands would just stink until the skin exchanged.

We were making them to create models of metal coordinating protein centers (which are often sulfur coordinated from cysteine residues) and to understand the electronic effects induced by steric hindrance.

I seem to have lived through the exercise.

Like I said at the outset, nobody really wants to know what the chemistry students emit.

[MannyGoldstein]

3. Engineering students using deodorants?

Things have changed since my day!

[NNadir]

4. I spend a fair amount of time hanging out in a university Engineering library.

Trust me, the days of the pocket protector ensconced dorky guys with pencil thin ties are over. Many of these young people, almost all of them in fact, are quite well groomed, and quite attractive, if, of course, you define covering one's self with cyclopolysiloxanes as "good grooming."

From a purely environmental standpoint, there may be something to sweat and bodily greases, but who am I to say?

It is interesting how many kinds of different chemistry are released into the environment without understanding their effects, some for completely gratuitous reasons.

On the other hand, modern mass spectroscopy techniques have advanced so far that in some cases we may be seeing things that have always been there, but have long been below detection limits until now.