Mould spores exist readily in nature and are an important part of plants, soil and natural decay.
Mould needs food and water to grow. The food is any cellulose material such as soil, wood, paper, organic debris, dust, fabric, drywall, carpeting, etc. The water can come in the form of high relative humidity, small water leak or flood.
If your relative humidity is too high or you have condensation you could have a mould problem. If you have had a water leak, roof leak, water appliance overflow, or flood you have 24 hours to clean it up before mould begin to grow.
The difference between mould growth outdoors compared to indoors is that outdoors there are a wide variety of mould types (genus and species) that keep each other fairly balanced.
Indoor mould growth usually involves one or a few types of mould species that greatly outnumber the concentration found indoors even outdoors. Mould amplification indoors is usually due to a moisture problem which will continue to fuel mould growth. As time goes by the problem can become larger, more severe and more difficult to clean up.
If the mould species found indoors is considered toxic or pathogenic and in large enough numbers, then a variety of health effects can occur.
Health effects can range from simple head aches, sinus or breathing problems to more severe nose bleeds, skin rashes, bleeding of the lungs, cancer, even death.
Many products exist that claim to rid your home or office of mould. What these products are not telling you is that a dead mould spore is just as toxic or allergenic as a live mould spore. The only difference is that it does not have the ability to grow any more. You still have a mould problem! Mould needs to be cleaned-up and removed from the indoor environment.
In many cases just as pesticides, the biocides used (including bleach) can cause a whole other problem of indoor environmental toxicity and pollution that is just as problematic as the organism it is intended to kill.
In some cases that is sufficient. However, you don't necessarily need to see mould growth in order to have a significant mould problem. Some moulds grow inside the wall cavity without any evidence at all on the visible portion of the wall.
In many instances mould may be visible in one room of a building, but the source of the growth is in another room or portion of the building which does not show visible evidence of growth in readily accessible areas.
Some of our investigations have resulted in significant mould growth findings where no mould growth was even suspected.
Although high relative humidity can cause mould growth, reducing the relative humidity to very low levels like 30% to dry out the mould is not advisable either. Drying out the mould can increase the chance of it aerosolizing. Mould has a natural defense mechanism where if disturbed, attacked or is dying, it will send out potentially millions of spores into the air that will settle and grow elsewhere. Avoid high relative humidity, but also avoid drying out. A relative humidity of 40% to 50% would be more advisable and have the mould tested and removed.
If you have mould growth you need to know why and how much. The source of the mould should be identified in order to avoid the problem repeating itself. If there is a roof leak or other moisture problem it needs to be fixed.
A mould test should be performed to determine how bad the mould problem is, what type of mould it is and if it's in any other portion of the building. With this data a proper method of removal can proceed. In some cases a carpenter can replace the drywall. In other cases the unaffected portions of the building, the occupants, and the people doing the mould remediation need to be properly protected.
Especially in scenarios where you don't really know the history of the building, it is advisable to test for possible mould amplification before removing walls, carpeting, or doing another structural work. If you start removing drywall and see the back side of it black with mould it is in many cases too late.
Sick Building Syndrome or Building Related Illnesses are increasingly the result of either careless building maintenance, careless renovating practices, or toxic mould exposure caused by aerosolized mould spores due to the removal of building materials without proper mechanical safe guards.
Using biocides or bleach to kill mould does not have any advantages. Dead mould is just as toxic as mould that is alive. Cleaning or removing mould without protecting the rest of the building or unaffected areas can in some cases spread the mould contamination. In some cases the mould becomes harder and more expensive to clean up. Some mould inspection companies lack the equipment or experience to properly assess you mould issue. They are cheaper...but are they worth it?