Industrial Hygiene in Construction

If you really have an indoor air quality and mold/fungus issue, it usually stems from moisture. I’ve talked about it before, here. The simplest answer is to find the water. Control the moisture and you inevitable will control the future indoor air quality concerns. Once you have found (and controlled) the water, then it is time to repair the damage and lingering water (which can’t evaporate).

The issue is: where does moisture come from? Well, it ‘can’ come from almost any direction:

• from above (rain, roof vents, skylights)
• from below (moisture in flooring, concrete)
• walls (penetrations into the exterior, or windows and flashing)
• out of thin air (relative humidity)

The EPA has written a new document titled, “Moisture Control Guidance for Building, Design, Construction and Maintenance“. As a contractor, how do you know when the clean up is too much to handle? I’ve written a bit more about it here.

The best time to clean up a moisture issue was yesterday, but the second best time to clean it up is today. Don’t let it sit, it usually doesn’t get any better.

Living in the NW, stucco is not as prevalent, compared to other areas of the US, as a building material. I finally got the opportunity to perform air monitoring for silica during stucco crack repair. From what the contractor explained, only the top layer of stucco (1/8 inch) is removed. He claimed the top layer is mostly an acrylic. The employee was wearing a 1/2 face tight fitting respirator with P100 (HEPA) cartridges. In addition, engineering controls were used.  The contractor had a grinder with a shroud and vacuum to remove the dust. This would not be considered a worse-case sampling scenario. From conversations with the plasterer-employees onsite, grinding is usually “VERY dusty”.

Sampling performed only for the duration of the grinding (3 hours). Conclusion?: We did not find any detectable levels of silica or respirable dust.

Please don’t use this sampling as the only information on how to proceed for your project. However, here are my observations:

• If acrylic material is the top 1/4 inch, you may not impact silica (or have any airborne).
• Airborne dust was very well controlled by grinder with shroud & vacuum (see pic below).
• Assume you will have dust until you can observe (or prove) otherwise. Wear a respirator.
• Perception is huge. If there is a big dust cloud coming from your grinder—even if there’s no silica… the observers don’t know the difference, and, well,…you know the story.