The diy mould treatment kit includes everything needed to complete a small mould remediation project

Unless the moist air is allowed to escape the environment inside a property warm and humid common household dust, containing microscopic spores of mould lands on wet surfaces and becomes the breeding ground for mould.  The most common types of mould found in homes are Aspergillus and Stachybotrys chartarum which can thrive on water damaged, cellulose-rich material in buildings such as sheet rock, paper, ceiling tiles, insulation backing, wallpaper, etc

Airing the rooms can aid in resolving damp and mould issues but for a total solution the problem has to be dealt with on a more professional level.

Once the cause of the dampness/mould appearance is established and you have rectified whatever was causing the excess humidity you can treat the areas affected by mould and repair the wall, ceiling or window as necessary.