Figure 6.1 Biological contact agar strips. (Biotest Diagnostic Corp.)

to increase their amplification rate. Steam cleaning can be beneficial with adequate drying cycles and in some instances the concurrent use of biocides.

Biocide usage can also be problematic. Chemicals that work in the laboratory may cause aesthetic and even health problems in the real world. Biocides often have limited residual time and may not even be tested against the particular biological contaminant mix of concern.

Residual time for any chemical mix has many unresolved questions; sometimes the chemicals' residual time in your particular circumstances is not even known. In other cases residual time may make the chemical unattractive because the toxic properties of the chem­ical remain and can cause contamination problems in and of themselves. We must always remember that the basic cellular structure of these biological contaminants and ourselves is the same, so chemicals that harm these contaminants may also harm us.

Recently, biocides with FDA and EPA approval have been developed and can be used in areas where biocides were formerly unacceptable. The decision in selecting the appro­priate biocide that will not harm humans, animal occupants, or damage structural materi­als can be a difficult one. Decontamination and rehabitation methodologies must be part of a coordinated remedial design effort.

One of the more common replies to all of this information is—why now? The answer is twofold; first, we probably always had these concerns once we lived for any length of time indoors; second, we have increasingly closed our buildings and relied on forced air ventilation systems. Both of these answers are also applicable to closed cab modes of trans­portation—airplanes, automobiles, rail cars, and ships.

In the past we thought that endpoint filtration of airstreams was sufficient to render delivered air relatively pure. We have now learned that filtration only works for a time, and excessive biological amplification can be transmitted through most current HVAC systems once established in ductwork or plenums.

If you suspect biological contamination, see visible mold growth, have personnel with repetitive mycosial infections, or have indoor air quality (IAQ) problems that have remained undiagnosed, you need to consult a team of professionals to find answers to these problems. In these cases not only is the mold growth itself problematic, but also we have to worry about the chemicals formed as colonies die. Dieback causes the chemicals formed during decomposition to be spread throughout building, and these are the same VOCs we worry about from chemical spills or misuse. The following sections speak directly to hazards associated with mold and fungi.

Дата добавления: 2015-11-16