Residential mould is very difficult to identify simply based on the colour or texture. The best way to have the mould identified is by contacting an expert or using a piece of Scotch tape to lift a sample of the mould off of the surface it has inhabited. The following mould varieties and the symptoms associated with them can lend an idea as to whether or not you or your home are at risk of dangerous mould growth.
Black mould can be toxic or non-toxic depending on the species, but the two most dangerous types are indeed commonly found in homes.
The first, Aspergillus niger is darkish gray and looks dry, and can cause respiratory infections or allergies, affecting those with weakened immune systems more adversely. Other species of mould in the genus Aspergillus can cause infections as well, and they can appear to be grey, green, yellow or white, ranging in toxicity. These moulds can be found in many places, from soil and clothing to walls and insulation.
The second, Stachybotrys chartarum, often has a greenish tinge and is usually slimy to the touch. It is the most famous of the toxic black moulds and can cause very serious symptoms ranging from nose bleeds and skin inflammation to pathological respiratory changes. This mould needs a very damp habitat to thrive.
Cladosporidium is a very common non-toxic black mould with no ill effects, but heavy exposure could aggravate allergies and asthma. It can be found in insulation, wood, dust and inside walls.
Penicillium is a relatively harmless mould, showing up as blue, white or green. It is what grows on the fruit and cheese that you forget about in the back of your fridge, but can also be found within the home. Some species can be somewhat hazardous.
One of the best ways to prevent mould is by eliminating the source of water or moisture in the area. Some mould covered materials can be thrown away, such as cardboard boxes. A scrubby brush and soapy water can also remove small patches of mould. Bleach kills mould, but does not remove it and dead mould can still trigger allergies.
Mould in the home is not just a health hazard, it can weaken the structural integrity of many building construction materials. A home inspector or other professional should be called in to estimate the damage done to your home.