Mold spores are tiny microscopic organisms that can only be seen under a microscope. Mold spores can become airborne just by walking near an affected area. Aspergillus and pennicillium mold can stay airborne for up to eight hours after one small air movement. Proper containment is a critical step; if not done correctly by a certified mold removal technician, the mold spores can spread and expand the required work.
Imagine what happens to air quality during mold remediation which involves multiple technicians, equipment, demolition, etc. You guessed it! It gets pretty bad and all that mold can travel through the air columns to previously unaffected areas if proper engineering controls are not put in place. This is one area where corners are frequently cut in the industry.
First of all, poly sheeting (typically 6 mil) should be installed in the work area to isolate affected areas from unaffected areas. These barriers should be well sealed and may have a zipper door or flap in place. Any holes, gaps, open soils, salvageable insulation, contents, seams, duct work, vents, or openings should also be sealed off to isolate the work area. Once this has been achieved it is imperative to install a negative air system to place the work space under negative pressure relative to the unaffected area. This prevents fugitive mold spores from escaping to other areas of the building. If mold spores are spread, it is the contractors liability and they are responsible for the damages. Negative pressure should be maintained between -4 to -6 pascals (measured by a machine called a monometer) to prevent creating too much vacuum. Too much vacuum can draw particulates in to your containment, draw in gases, and can put excessive pressure on your poly sheeting which could cause collapse. It is crucial to monitor pressure differentials especially while entering and exiting your work space. Any time you enter or exit your work area, you open the sealed off space and air rushes in. Pressure must always stay negative (vacuum) or you could spread contaminants upon opening your barrier.
Air scrubbers must also be utilized to condition the air during the mold remediation work. Air scrubbers are large HEPA (high efficiency particulate air) filtered machines that clean the air at a given rate per hour. Depending on the project the goal should be to achieve an air exchange rate of at least 3-10 air changes per hour. This is calculated by taking the square footage of the area and the ceiling height to determine the cubic footage. Once this number is calculated air scrubbers should be employed accordingly to clean every cubic foot of air x number of times per hour. This keeps the work area as clean as possible throughout the remediation process. Air scrubber filters should be cleaned or changed based on project requirements. Many projects will also require special low grain dehumidifiers, supplemental heat, supplied air machines, make up air filters, etc.
Every mold remediation project is unique and will have slightly different requirements; however, this can serve as an overview you can use to better understand the remediation process. Proper containment is a critical step that if not done right can simply spread the problem and expand the required work. In our next article we will discuss the actual mold removal process which can involve a number of different approaches.