Non-Culturable Air Sampling

Overview

Non-culturable spore trap samplers draw measured volumes of air through the sampling device for a specified length of time. The collection surface is a coated glass slide. Particles in the air (spores, dust, etc.) impact onto the sticky surface and are “trapped” for later analysis.

A general philosophy regarding the interpretation of biological air samples is formed primarily by two guiding principles. First, an effective interpretation is based on the comparison of indoor and outdoor samples. There are currently no guidelines or regulations to indicate “safe” or “normal” spore levels, however, we typically expect indoor counts to be 30 to 80 percent of outdoor spore counts, with the same general distribution of spore types present. And second, variation is an inherent part of biological air sampling. The presence or absence of a few genera in small numbers should not be considered abnormal.

Pros

Spore trap samplers are capable of capturing all spores and particulate matter in the air. Consequently, it is possible to accurately characterize problem environments where spores are present but either are no longer viable or are species that do not culture well (i.e. Stachybotrys). These are two situations where culturable sampling techniques, if used alone, may miss a potential indoor air quality problem.

Cons

While many mold spores have a unique morphology and are identifiable by direct microscopic examination, others do not and are more difficult to identify. These latter types must be counted in broader spore groups.

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Culturable Air Sampling

Overview

Culturable air sampling is one of the most common methods of volumetric air sampling. The sampler works by drawing measured volumes of air through an instrument that contains a petri dish (or dishes) with culture media. Spores that impact onto the plate are then allowed to incubate and grow, after which the colonies may be counted and identified.

A general philosophy regarding the interpretation of biological air samples is formed primarily by two guiding principles. First, an effective interpretation is based on the comparison of indoor and outdoor samples. There are currently no guidelines or regulations to indicate “safe” or “normal” spore levels, however, we typically expect indoor counts to be 30 to 80 percent of outdoor spore counts, with the same general distribution of spore types present. And second, variation is an inherent part of biological air sampling. The presence or absence of a few genera in small numbers should not be considered abnormal.

Pros

Culturable air sampling allows for the differentiation of Aspergillus and Penicillium (speciation when required). It also provides counts indicative of how many spores are viable and present in the air. It can also be used to provide a bacterial count.

Cons

Culturable air sampling methods require that the spores in the air are alive, survive the sampling process, germinate on the sampling media, and compete well with other species present on the growth media. Culturable air sampling does not indicate the presence of non-viable spores, which may also be capable of producing allergies or irritation. Culturable air sampling also requires five to seven days for incubation after the sampling has taken place.

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Dangers of Ozone Machines – Part 2

Other Potential Residential Damage

Environmental ozone causes more damage to plants than all other air pollutants combined. Similarly, ozone generators can damage plants in indoor environments. High levels of ozone will inhibit the ability of plants to open the microscopic pores on their foliage and breathe. Specifically, ozone can cause the following conditions in plants:
  • chlorosis, a condition in which the plant cannot produce sufficient chlorophyll to manufacture carbohydrates;
  • necrosis, or the premature death of living cells, which may lead to the death of the plant as a whole;
  • flecks or small light tan irregular spots;
  • stipples, which are small, darkly pigmented areas; and
  • reddening.

Damage To Building Materials

In addition to human and animal health, excess ozone can damage the following materials:
  • carpets, especially synthetic carpets;
  • carpet padding;
  • foam cushions;
  • other plastic furnishings and furniture covers;
  • rubber pads and padding;
  • electrical wire coatings; and
  • fabrics and art containing certain dyes or pigments.

A lot of remediation contractors are using ozone and most do not know the dangers that ozone can potentially cause.  Some newer contractors are always looking for the quicker method that eliminates the use of employees and also has quite simply, a fancy name to entice potential clients.  There’s always new methods and machines being invented and used every year in mold remediation, but the “old time” use of hand remediation is without question, the safest and best method for mold remediation.

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Dangers of Ozone Machines – Part 1

Ozone generators intentionally produce the toxic gas ozone and are sold as air cleaners for commercial and residential applications. Specifically, they are advertised to deodorize, disinfect, kill or remove dangerous or irritating airborne particles in indoor environments.  Ozone is the principal element of the ozone layer, which traps the sun’s heat and is essential to life on Earth. Unlike breathable, stable oxygen molecules, which are composed of two oxygen atoms, ozone is composed of three. The third oxygen atom in ozone can easily detach from the ozone molecule and reattach to other substances, altering their chemistry. Ozone generators produce the gas in large enough quantities that unstable organic compounds will react with the gas and, supposedly, be altered so that they will no longer be irritating or dangerous.

  • Note that ozone can dull the olfactory sense, a fact that has led many experts to believe that ozone’s deodorizing abilities are at least partially due to an altered odor perception, rather than any change in the environment.

Health Considerations

Unfortunately, the same chemical properties that allow ozone to alter organic material in household air also give it the ability to react with organic material inside the human body. Even low levels of ozone exposure can cause the following conditions:

  • coughing, chest pain, shortness of breath, wheezing, and throat irritation;
  • worsened chronic respiratory diseases, such as asthma;
  • increased risk of developing bronchitis or pneumonia; and
  • compromised ability of the body to fight respiratory infections.

People’s susceptibility to ozone varies widely. An ozone generator should never be operated in occupied spaces, and the area should be adequately vented before people or animals are allowed to re-enter.

According to a report produced by the EPA, ozone generators are ineffective at reducing levels of formaldehyde and carbon monoxide, despite claims by manufacturers. Also, from the toxins with which ozone does react, there is a potential for the creation of new, potentially more dangerous toxins. For example, ozone mixed with chemicals from new carpet can create aldehydes, which can irritate the lungs. Other reactions may create formic acid, another irritant. The potential for chemical reactions in the average house is difficult to predict.

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Using Ozone for Remediation

I know this is an ongoing question, and there are remediators who are recommending ozone for cleanup. However, although ozone can damage some fungi, there is not a single study in the peer-reviewed literature that documents sufficient deactivation of fungi to be useful in remediation efforts. Most of the studies of ozone are found in the food industry. Ozone is effective in slowing the growth of fungi on fruits and vegetables. However, under these circumstances, slowing growth for even a few days is considered significant. Delays in spore production as long as 5 days have been reported. While significant in the life of a vegetable, this delay is useless for a residence.

It is true that very high levels of ozone over several hours will significantly lower the concentrations of culturable fungi on hard surfaces. At these concentrations, however, the ozone will damage building contents. Also, ozone disappears rapidly from the air. It attaches onto surfaces, including valuable ones that could be damaged. Data from studies that assess fungi on materials in houses have not been impressive. Fifty percent reductions have been achieved, and considered significant. However, reducing fungal concentrations on a surface from 50,000 to 20,000, although it may be statistically significant, is not important in a remediation sense. Also reported is the fact that fungi are more readily damaged by ozone on smooth, hard surfaces than on porous surfaces.

Unfortunately, fungal growth is most likely on porous materials (such as wallboard) from which it is difficult to remove, while a simple wipe with a damp cloth will remove fungi from smooth surfaces. Remember also that dead fungi may cause as many problems as living ones. It is far more effective to not worry about whether or not the fungi are alive, but instead concentrate on fixing the water/humidity problem and removing materials with fungal growth.

Overall, then, given the potential dangers of ozone damaging building contents and the possibility of negative health effects both for remediators and for occupants, I would not recommend it’s use. In fact, given the negative literature, I would suggest that the use of ozone is contraindicated in mold remediation situations.

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Surface Sampling Overview

There are other simple sampling methods that may be used to supplement volumetric air sampling. Surface samples are taken by tape lift imprint, by swabbing the suspect surface with a culturette swab, or by submitting a bulk sample of the suspect surface. We typically recommend that a direct microscopic examination be performed on surface samples. While culturing a surface sample may help resolve a specific identification problem, used alone such a culture may result in an inaccurate characterization of the surface sampled. A direct microscopic examination of a surface shows exactly what is there, without being affected by an organism’s ability to compete and grow on sampling media.

The primary purpose of a direct microscopic examination of a surface is to determine whether or not mold is growing on the surface sampled, and if so, what kinds of molds are present. Secondarily, most surfaces collect a mix of spores which are normally present in the environment. At times it is possible to note a skewing of the normal distribution of spore types, and also to note “marker” genera which may indicate indoor mold growth.

In addition, when mold growth is present indoors, many more spores of a particular type will be found trapped on surfaces. These spores may be in forms which indicate recent spore release (close proximity), such as spores in chains or clumps. Marker genera are those spore types which are present normally in very small numbers, but which multiply indoors when conditions are favorable for growth. These would include cellulose digestors such asChaetomium, Stachybotrys, and Torula. While a single Stachybotrys spore is occasionally seen as part of the normal outdoor flora, finding 5 or 6 of these spores on a single scotch tape slide of a duct surface is an indicator that Stachybotrys may be growing indoors.

Pros

A direct microscopic examination of a surface shows exactly what is there, without any skewing by laboratory procedures. Surface sampling is inexpensive and (for a direct examination) may be analyzed immediately. Surface sampling may also reveal indoor reservoirs of spores which have not yet become airborne.

Cons

The presence of biological materials on a particular surface is not a direct indication of what may be in the air. Health problems related to indoor microbial growth are generally caused by the inhalation of substantial numbers of airborne spores, sometimes over a substantial period of time (exceptions being, for example, situations involving small children or immuno-compromised individuals).

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Radon Health Effects

Radon is a radioactive gas that causes cancer. Radon is found in rock, soil, water, some building materials, and natural gas. You can’t see, taste, or smell it.

Any home, school, office, or other building can have high levels of radon. Radon is found in new and old buildings. It can seep in through the foundation of a house built on radon-contaminated soil. If a house’s water supply contains radon, radon may enter the air inside the house through pipes, drains, faucets, or appliances that use water. Then the radon may get trapped inside the house.  Radon sinks to the low points in buildings, so it often is found in basements. But a building can have high levels of radon even if it doesn’t have a basement.  Studies show that nearly 1 out of every 15 homes in the United States has unsafe levels of radon. If you live in an area that has large deposits of uranium, you may be more likely to be exposed to high levels of radon. (To see a map of the U.S. radon zones, see the website http://www.epa.gov/radon/zonemap.html.) But the construction features and exact location of your house may be just as likely to affect your risk. Even houses right next to each other can have very different radon levels.

Over time, exposure to radon can cause lung cancer. Radon causes about 21,000 lung cancer deaths each year in the U.S. It is the second leading cause of lung cancer, after tobacco smoking. People who smoke have an even higher risk of lung cancer from radon exposure than people who don’t smoke. Radon exposure doesn’t cause symptoms. Unless your home or office is tested for high radon levels, you may not realize that you are being exposed to dangerous levels of radon until you or someone in your family is diagnosed with lung cancer.

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