Of the many issues affecting indoor air quality, one of the more dangerous offenders, and more difficult to remediate is Aspergillus niger.
A. niger is actually quite common as a mold seen on rotting fruit and breads. More often we know to avoid foods covered in mold, however A. niger was likely present long before we saw it with the naked eye, and we often eat food often blissfully unaware of its presence. We rarely feel these effects due to the fact that when ingesting something orally, the body has natural filters such as the stomach, gut lining, liver, etc. to filter out impurities. Within confined spaces such as our homes and offices, A. niger spores and their off-gassing Mycotoxins are inhaled, and by directly entering the blood stream through the lungs, the body loses that natural mode of filtration action which can lead to lung issues such as Aspergillosis, particularly among the elderly and immune-compromised.
When trying to fight A. niger in home and commercial spaces, you need to understand your enemy. For example, A. niger, as the name implies, has a spore shell with a higher melanin content, which makes it more resistant to UV and heat treatments. As well, it is a Saprophyte, meaning it thrives on decaying organic matter such as houseplants, skin cells, and exposed wood. Lastly, it is asexual, meaning it doesn't need a partner to reproduce so while one spore can become an outbreak if it finds the right conditions (95+ degrees 88%+ Humidity), the other spores can lay dormant to produce a problem in the future. The tactical responses are heat treatment (149 degrees for 30 minutes-if your internal spaces can handle it), Carbolic Acid (.1-1% for 20 minutes), Bleach (6-10% for 10 minutes), and H2O2(6-10% for 10 minutes), and keeping Marigolds indoors which create a gas toxic to A. niger. However, from a whole-home perspective looking forward, you need look at Prevention and Detection issues such as HVAC and how often your filters are changed, the ability to catch air quality issues early, and your behavioral issues such as preventing cross-contamination between yourself and surfaces.
In short, everything you do to prevent A. niger from entering the home or office, thriving within those environments, and traveling around those environments will put you that much further along on the path toward managing risks that can affect the health and well-being of you and those around you.