How to Determine and Successfully Clean up Condition 2 Settled Spores

Transcription

1 How to Determine and Successfully Clean up Condition 2 Settled Spores William Vaughan, Phd, QEP President, Principal Scientist Nauset Environmental Services, Inc. East Orleans, MA Settled mold spores are NOT REMOVED by the limited methods many mitigators use. Yet settled spores are now afforded the recognition they are due as potential future contaminants and irritants. In the Institute for Inspection Cleaning and Restoration Certification (IICRC s) ANSI- S520 (2008), Standard and Reference Guide for Professional Mold Remediation (August 2008), excess settled spores now constitute Condition 2 contamination, requiring professional mold remediation. An initial air sample can show low spore levels and the place looks great yet it may still be contaminated by settled spores. A quiet sample taken with a spore trap or culture plate measures only those spores that have not yet settled and can be quite misleading. I have encountered many situations where visual inspection has led the mitigator to conclude that things look pretty good, yet there may well be Condition 2 contamination. Settled spores are a critical element in IICRC s approach to mold cleanup spurred by knowledge of the health impact of molds and the fact that mold spores are biological organisms, capable of recontaminating a space! [REMEMBER: If you were to remove 99.9% of oil, PCB or lead contamination and the area was impacted by a leak, you would have only 0.1% of the original contamination. If you remove 99.9% of mold spores and a leak occurred, there is a good chance that the area will be re-contaminated, since molds spores can grow and reproduce, increasing their numbers.] HOW DO YOU KNOW THAT THERE ARE SETTLED SPORES PRESENT INITIALLY or LEFT BEHIND FOLLOWING HEPA CLEANING? - Some professionals recommend taking tape lift or swab samples to determine the presence of Condition 2 contamination, as part of a pre or post-remediation sampling (PRS) or assessment; but where do you take those individual samples?? Floors? Walls? Easy to reach places? Every stud bay? Every fifth stud bay? Also how many samples do you need from each lift/wipe location? Will the pressure for scientific confidence be severely compromised by real-world budget constraints? One approach to these assessment dilemmas, both pre and post-remediation, is to take disturbed air samples. We at Nauset Environmental Services, Inc. (NES) have been utilizing disturbed air sampling since 2002 and find it very cost effective in addressing Condition 2 mold contamination.

2 The advantage of disturbing the air is that settled spores from many areas of the room, including rafters in cathedral ceilings, nooks and crannies in awkward corners, baseboard heat exchanger fins, etc. can be impelled into the air and mixed so that they can be sampled in a traditional way. The disturbance integrates settled spores from many possible locations in a room/area. The disturbance simulates, to some extent, human activities that could remobilize those settled spores to travel to uncontaminated areas after containment barriers are removed. Those activities might include: Fans set up for cooling occupants or providing general ventilation. Remodeling activities that involve dropping supplies or material, like dry wall panels, onto the floor. Vacuuming floors, carpets, woodwork, etc. in the normal course of house maintenance. During these normal human activities, settled spores can be kicked into the air by drafts and then slowly settle onto the new/cleaned surfaces in a room/area after refurbishing. NES s idea has been to simulate occupant activities with drafts from a typical table fan while there is still a chance to make sure the cleaning activity has been reasonably effective and, if not, suggest further air polishing of the room/area to reduce the settled spores even more. HOW CAN YOU DISTURB THE AIR WITHOUT BEING NON-REPRESENTATIVE? - At first NES took on the guidance for the asbestos abatement industry where leaf blowers are operated and moved about within containment areas for extended periods of time before and during air sampling. These aggressive clearance samples are called for under standard EPA protocol and must result in very low fiber counts before an area is declared clean enough to be re-opened for occupancy. NES was criticized for this approach, even though it did point out areas where additional remediation activities were required. The criticism was that those extremely strong drafts were not typical for lived in spaces and resulted in too stringent a cleanup challenge in light of the absence of firm clean-up guidance. NES then switched to using 12 household fans, either table or stand styles. These are the type and size fans purchased to provide ventilation and cooling in homes. That decreased level of disturbance was considered acceptable in a living space and not extreme, as the leaf blowers were. The technician disturbs the air by holding the fan and directing it around the space being sure to blow back and forth across the floor, across moldings and horizontal ledges, into baseboard fins, into corners, and any place one can imagine where spores could have settled in a room. Two to three minutes of waving the fan is usually sufficient to cover most surfaces, obviously longer for larger areas. NES does not take a disturbed air sample by itself to determine Condition 2 contamination, but pairs it with a traditional quiet air sample to see how much the airborne spore levels change when the settled spores are mobilized into the air. In this way two samples, usually total spore air trap samples, give a fairly thorough, integrated picture of mold spore contamination in a

3 room/area. By using the total spore number, NES focuses on the health impact for occupants, since both viable and non-viable spores can cause allergic reactions in sensitized individuals. (Of course at least one outdoor air sample is taken during these efforts in non-winter conditions in order to compare the mix of spores outdoors with those indoors to demonstrate any waterinduced mold amplification.) Here is an example of what NES s paired samples have found and how they have been used: EXAMPLE - Failure of two baseboard heaters led to damage from direct water as well as condensation. Four separate areas in the house were contained and remediated by HEPA vacuuming and wiping down. NES was brought in for post-remediation sampling (PRS) at a time when the outdoor total spore level was 2,650 S/m 3. Chart 1 (above) shows the initial post-remediation air sample pairs (quiet and disturbed) in each of the four areas. In Areas A and C, disturbing the air with the 12 fan stirred up few additional spores. In Area B, near one of the leaks, the total spores were initially at 1,222 S/m 3, a seemingly acceptable level compared to the 2,640 S/m 3 in the outdoor air. However, the total spores increased 18-fold after the fan s drafts suspended them, but, within that sample, the Aspergillus- Penicillium (Asp-Pen like) spores ( A-P in the chart) increased 24-fold! Those are significant

4 differences (i.e. well over an order of magnitude) indicating a reservoir of settled spores persisting after the traditional remediation. In Area D, on the floor below the other leak, the difference in levels induced by the fan s drafts is much more dramatic. The initial quiet conditions at 944 S/m 3 again seem to be quite acceptable. However, the total spore levels increased some 41-fold under the influence of the drafts with Asp-Pen like spores increasing some 120-fold! There are numerous other examples that can be cited where NES has used this disturbed air technique to reveal extensive Condition 2 contamination. The bottom line is that the additional information from a disturbed air sample can point to the need for initial or further remediation to reduce Condition 2 contamination and it is more cost-effect and has less sampling bias than isolated tape or wipe samples from somewhat arbitrary locations. HOW DO YOU CLEAN UP CONDITION 2 SETTLED SPORES? One must realize that settled spores have eluded the traditional carpet fan and air scrubber approaches to remediation. They do that because they are solid objects and cannot jump into the air on their own. They need drafts. BUT not any draft will do. If you are trying to remove leaves from a driveway, you sweep the leaf blower back and forth across the surface and gradually corral/move the leaves into the pile you want. You know that if you just set up the leaf blower in the driveway and walked away, you would move the leaves off the surface only in the direct path of the exhaust while leaves on either side would just lay there even though the leaf blower s blast is very strong. Similarly, on a much smaller scale, a carpet fan that is blowing in one direction without being redirected can mobilize only those spores in its direct draft, not those to the side, much less those in the room behind it. NES s approach to reduce settled spore levels is to direct remediators to follow an Air Polishing protocol AFTER their traditional approach. That protocol involves maintaining the containment and, with worker s still wearing protective gear, then: Set up an air scrubber in each area or room remediated, as opposed to operating in the negative air mode under which spores outside the containment could be drawn into the newly cleaned space. Set up 2-3 oscillating fans (similar to those used to disturb the air in the above discussion) in the same area/room to minimize stagnant air zones. Be creative with aiming oscillating fans since they are not there for the comfort of inhabitants in the center of the room, rather for minimizing the quiet areas where spores can settle at the edges/corners of a room. One can use stand-type oscillating fans aimed up to rafters, exposed beams, shelves, etc. to stir up spores on those surfaces. If there are several gutted rooms with a common air space, bounded by studs and incomplete partitions, a single air scrubber may still work. Use multiple smaller oscillating fans in the smaller areas to keep nooks, crannies and corners disturbed and

5 add one or more carpet fans to develop a circulation pattern to direct the suspended spores to the central air scrubber. Periodically, 2-3 times a day, use a strong fan or leaf blower to stir up the settled spores left over after the remediation activities so that they can eventually be moved to the air scrubbers on drafts from the fans and be filtered out of the air. Direct the leaf blower to all corners of the room and elevated surfaces that are difficult to reach. In addition, reposition or redirect the air scrubber(s) exhaust as well so that it hits a new corner or quiet zone after each visit. Be sure to direct drafts to any baseboard fins in the room. Operate the oscillating fans and air scrubber(s) for at least hours in each area/room after the traditional cleanup is completed, periodically revisiting the room/area for leaf blower mixing and ALSO repositioning the smaller fans after each leaf blower visit to reduce the dead zones where spores can settle out and collect. To indicate the effectiveness of air polishing alone and no additional HEPA vacuuming in the example above look at the data in Chart 2 (below).

6 In Area B the quiet spore levels have been reduced to under 600 s/m 3 and the disturbed spore levels were only increased by less than 3-fold, compared to 18-fold before air polishing, and Asp-Pen levels by less than 6-fold, compared to over 22-fold before air polishing. In Area D the effect of air polishing is more dramatic. The quiet air sample now has total spore levels just over 2,100 S/m 3, down some 88%. When disturbed, the total spore readings now increased just over 5-fold, compared to over 41-fold earlier, with Asp-Pen like spores increasing just over 4-fold to only 244 S/m 3, compared to the 120-fold increase to nearly 39,000 S/m 3 initially. CONCLUSION: The air polishing technique has been demonstrated to successfully reduce the level of total spores in areas B & D of this house, without any additional HEPA vacuuming. The use of strong leaf blowers at the air polishing stage, NOT at the initial, pre-remediation stage, aggressively moves settled spores into the air for filtration by air scrubbers. There are likely to be fewer settled spores left over under this approach, resulting in a higher likelihood of a successful PRS evaluation and fewer return trips to complete the remediation saving money for the client and shortening the total remediation effort. Dr. William M. Vaughan is President and Principal Scientist for Nauset Environmental Services, Inc. He received his PhD in Biophysics in 1969 and his Qualified Environmental Professional (QEP) credentials in 1994 from the Institute for Professional Practice in recognition of his then more than 20 years of multi-media environmental experience. His speciality over the years in runnng three companies has been air quality investigation, both ambient and indoor. He can be reached by at nesinfo@capecod.com or by phone at