One of the most common requests PureLiving gets is to test for and treat mold problems. This is the story of a typical client’s troubles with mold and what we did to help.
Why were we called?
Our clients were an expatriate professional couple from the UK with one toddler and a baby on the way. They had only recently arrived in Shanghai and were settling into a renovated 1920′s lane house near Fuxing Park. All members of the family were generally healthy, although both adults do have some history with seasonal allergies.
As the house had been empty for some time, it required extensive cleaning prior to move-in, and our clients observed quite a bit of black dust. They also noticed that the back of their kitchen drawers and cabinets always felt damp, and so they replaced the enclosed cabinets with open shelving. This helped somewhat, but the dampness persisted. Although all visible mold had been cleaned and odor had been minimized, the perpetual dampness remained and they were concerned enough to contact PureLiving to see if the home was safe for habitation, and what could be done to minimize conditions that would allow mold to return.
What did we do?
Whenever we test for the presence of mold spores, we capture at least three samples – one in the suspected area, one in a seemingly unaffected ‘control’ room for reference, and one outdoors to evaluate atmospheric conditions. By comparing the readings in the three areas, we are able to make a more accurate assessment of the overall situation than with just a single sample. In this particular case, we tested the kitchen, the master bedroom, and the lane just outside the home. We also made a comprehensive visual inspection of the kitchen area, including exterior walls, looking for potential sources of dampness, and we used equipment to measure the level of humidity in the air as well as within the walls themselves.
What did we find?
On the day we visited the clients’ home, the weather was dry and cold, with no wind and low humidity. This means that if we were to find high humidity indoors, its source is also likely indoors, and not a result of weather conditions.
Our outside spore sample indicated a fairly low presence of mold spores, and those detected were largely of a variety common to the outdoors but usually found in low concentrations indoors - a strain of basidiospores, spores for a genus of fungi that includes edible mushrooms. These spores also appeared to be ‘loose’ and not clustered together, which indicates that they are just random spores drifting about in the air in low concentration (630 counts per cubic meter of air, or cts/m3) – entirely normal and harmless.
In our control room, the master bedroom, we did find a higher concentration of mold spores than in our outdoor sample: 930 cts/m3. Some of these were basidiospores as mentioned above, which likely had drifted in from the outdoors at some point though an open door or window. The majority of spores detected, however, were aspergillus, a genus of mold with several hundred varieties, some of which are essentially harmless, some even quite useful in medicine and food production, but others of which are potentially toxic. At the level detected in this area, though, there was no major cause for alarm, and as with the outdoor sample, the majority of the spore were loose – another indication that the spores detected in this room were not coming from a source within the room itself but were drifting in from other areas. Some, however, were organized into chains and clusters, which did indicate that somewhere not too far away there likely lurked a substantial colony as their source.
The kitchen sample certainly provided an answer to the question as to where that source might be! Results from the kitchen spore sample demonstrated a concentration of 130,000 cts/m3. This was more than 200 times the concentration of spores as in the outside sample; furthermore, 100% of spores in this sample were aspergillus as opposed to basidiospores. Certainly, this room contained the source of the aspergillus detected in the master bedroom – spores were no doubt traveling throughout the home by hitching a ride on air currents, and on our clients’ clothing, hair, and slippers as they went about their daily business. The spores collected in this sample were so densely packed onto the sample collection device (essentially a fancy bit of sticky tape inside a tube that has had air pulled through it) that the lab was unable to analyze the percentage of spores arranged into clusters versus those that were loose, but at this concentration it was a moot point – without question somewhere in this room a thriving colony of aspergillus was surely and steadily trying to expand its territory.
As part of our visual inspection of the kitchen, pulling away the kickplates from the crawlspace under the sink and cupboards revealed a portion of flooring that had not been sealed and felt damp. However, we still could not find an obvious source of moisture nor an obvious area of water damage. We did observe a pipe on the exterior wall that was seemingly disused, and it is possible the some moisture was seeping in via this route, a common problem with old lane houses.
What did we recommend?
As no definitive source of moisture was found, our recommended course of action focussed on thoroughly – and safely – cleaning the affected area, decreasing the existing moisture level, and preventing future mold growth by limiting the conditions for it to develop.
First and foremost, to ensure that cleaning would be effective, would not spread more spores throughout the home, and would not adversely affect the clients health, we recommended emplacing good quality air purifiers with HEPA filters in the room before starting to clean, and closing off the room as much as possible for the duration of cleaning. N95 protective masks were worn throughout the cleaning process.
The initial step in cleaning was to use a vacuum cleaner with a HEPA filter and hand held nozzle to vacuum every surface that could possibly be reached. Following vacuuming, all boards were wiped down with a chlorine dioxide solution. (Vacuuming first is a very important step in cleaning mold-affected areas – wiping without vacuuming first will remove some surface mold, but will also send a large percentage of it flying into the air, or just shift some it around on the surface.) Following thorough cleaning, all cabinets and drawers were left open to dry and ventilate, and the HEPA filters were left to run on high for 24 hours to capture remaining airborne spores.
In order to inhibit future growth, chlorine dioxide sachets were placed under the sink area, and a small dehumidifier engaged to maintain a low moisture level.
Did it work?
Almost three months after our initial visit, we returned to our clients’ home to take more samples in order to validate the effectiveness of the cleaning and prevention methods. On this second visit, the weather conditions were rather different – it was warmer and more humid outside, and had rained somewhat recently. As a result, the outdoor spore count was nearly twice as high as it had been on our first visit, at 1200 cts/m3. But again, these were predominantly basidiospores, and entirely within the range of normal for outdoors.
The results for the kitchen were of course what we most wanted to see. From the initial reading two months prior of 130,000 cts/m3, the spore count in this room had dropped to an amazing – and very reassuring – level of 260 cts/m3! Furthermore, 95% of the spores detected in that count were basidiospores, which almost certainly had come in from the outside. In other words, the aspergillus had been very nearly eradicated, and was being effectively prevented from returning.
What do the clients have to say?
“When we moved into our lane house we decided to get it tested. We’re not the kind to worry unduly but we have a young family and wanted to be sure. We were very pleased with the service we got from PureLiving. We were reassured to find out that there was no lead in the paint, no risk from formaldehyde in the new furniture and nothing serious to worry about in our mains water. And the impartial advice we were given on the factors to weigh up when buying air purifiers probably saved us the cost of the testing.
Most importantly we discovered that we had a big mold problem. We’d already noticed the smell of mildew and had done our best to mitigate the worst of it in the kitchen cabinets. But we were unsure what the source was or how much of a health risk it posed. The testing turned a nagging uncertainty into a known quantity (200 times normal levels to be precise) and we were given good practical advice on how to deal with it.
After a bit of elbow grease and the loan of PureLiving’s industrial HEPA vacuum cleaner we were on top of the problem and just in time. A few days later our new baby came home from hospital to a mold-free house (well, at least a house with mold levels no higher than the outdoors) and it has stayed that way since. We’d highly recommend the service to anyone, who like us, needs peace of mind about their home in China.”