Samplers side by side

[Guest guest]

:

I have....several times. More often than not, it was to prove a point, i.e., that bioaerosols come in puffs and wiffs and even when sucking the “same” air, results are not necessarily uniform or statistically sound.

One round of sampling I did that had the considerable variability was a 5-unit complex of four-story office buildings. It was called: The Park. Lots of greenery and every office space had an openable window to a green space. Because of a title transfer and refi, a firm was brought in to inspect and collect air samples. Their inspection found nothing out of the ordinary, but their air sampling detected some Stachy spores present. Based on finding a few Stachy spores, they opined that the whole facility was contaminated with “hidden” water damage. Then I was brought in. My inspection was more through. Yes..I found some small issues here and there (e.g., water cooler leaking, several kitchenette sink drains leaking, a leaking aquarium, etc,), but nothing significant. Moreover, I selected 7 of the other firms indoor sampling locations with the most “significant” data. I set-up two spore traps (Air-O-Cell) and two single-stage agar plates (four samplers total) at each location, and collected the same 5-min air sample – all sample pumps plugged into the same power-strip that was turned on at the same time. All four samplers were 10-inches from each other, in a 2-ft square.

For the more common molds (e.g., cladosporium, penicillin, aspergillis, and unocladium) the results were somewhat uniform and statistically sound – they were not identical! For those molds where there were much fewer particles in the air, the results were varied, not consistent, and not statistically sound. I recall that there was a Stachy spore here and a Stachy spore there, but not one location had Stachy spores detected in all four samplers, and only one location had Stachy spores in two samplers – one spore trap and one .

Bottom line...one or two Stachy spores present does no constitute gross contamination.

I also did something similar, but only involving outdoor samples, at an apartment complex. Similar sort of results, i.e., those molds with a lot of airborne particles tend to be more uniformly represented than those with fewer airborne particles. This effort was also performed morning, noon, and late afternoon, and the make-up of collected mold spores was different given different times of the day; which I believe biased by the diurnal wind direction. Moreover, those sampling locations near to and downwind of where the landscaper was cutting grass and shearing hedges were loaded, and loaded with different and unusual mold species, e.g., rusts, smuts (ustilago), typhula, etc., and it was only in these locations where results of all four samplers appeared nearly identical; albeit, the samplers were loaded with the landscaper’s residue.

For what it is worth....

Bob:

Just curious, have you ever placed two airborne mold samplers side by side at the same time and compared the results?

Has anyone else?

W. Bearg, PE

Life Energy Associates

www.LifeEnergyAssoc.com

20 Darton Street

Concord, MA 01742