What is Mold

What is Mold

Mold (also called mould) is a fungus (microscopic plants) that grow on various things like damp places, food items etc. Ever noticed those scary looking growth on rotten fruits, vegetables or the black spots in the bathroom. That is mold.

Mold grows in places where there is moisture (or damp), lack of fresh air and moderate temperatures. They cannot grow under direct sunlight. Bright sunlight inhibits the growth of mold.

Mold survives and draws nutrition from the very surface it grows on. It grows most commonly on decaying and rotting organic matter like fruits, vegetables, wood etc. Inside the house mold grows in many more places apart from just organic substances.

Where does mold grow

Mold appears quickly on damp ridden walls, ceilings, wooden structures and all places in the bathroom for example. Where-ever there is water contact or moisture staying for long time, mold finds a conducive environment to thrive.

Apart from walls and wooden structures, mold can even grow on clothes, carpet and similar things. If you leave the carpet wet for long and do not give it a wash once every few days, it would start smelling bad and eventually develop mildew growth.

Mold on walls
Mold on walls

Mold appears even on the outdoors. Just like the inside of the house, wooden and wall structures on the outside of the house also develop mold growth when there is too much damp or water contact persisting for a long time.

What causes mold to grow

Most species of mold need moisture and moderate temperature to grow. You would rarely see mold growing in dry places. Moisture or damp problem is fundamental to mold growth. There are a number of reasons why moisture may become a problem inside your house.

Some of the common reasons include, humidity, water leakage through water pipelines or from faulty roof ceilings.

Some mold species are Xerophilic in nature and can grow in places with little or no moisture by only humidity. For example the mold that grows over bread which has been left to rot. However most of the mold species need accumulation of moisture to be able to grow.

Mold growing on fruit
Mold growing on fruit

Besides moisture, the other key factor that favors mold growth is moderate temperature. Apart from very hot and very cold temperatures, mold can grow under all other temperatures. There are some mold species that can even lie dormant under cold climates and start growing again when the temperature is right. Mold can grow at temperatures as low as 2 degree celcius. However very hot conditions generally inhibits the growth of mold and kills it.

Mold Biology and cellular structure

Mold grows in colonies. A mold colony is considered a single organism. The main body of a mold colony is called mycelium and it is made of a network of multi-cellular filaments called hyphae. It is only when the mold colony becomes large enough, does it become visible to the naked human eye.

The tips of the hyphae release enzymes that breaks down the compounds present in the underlying surface on which the mold is living. The mold then absorbs the nutrients from the underlying surface and continues growth.

Mold spores

Under favorable conditions of temperature, oxygen levels and available nutrients, the mold produce spores at the end of the hyphal cells. These spores act like seeds, and reproduce the mold elsewhere.

The spores are carried away by air flow elsewhere and if they land on a surface that is suitable for growth of mold, the spore will germinate into a new hyphal cell and begin the growth of a mold colony.

If mold starts growing in one corner of the house, the spores originating from it can float to other parts of the house and spread pretty fast. Since they are not visible it can be difficult to clean and remove them completely without proper inspection. More over some of the spores are resilient enough to stay dormant for years before they find suitable environment to grow.

What is Toxic Mold

Now that we have understood the basics of mold, it is now important to learn about it toxicity and what it is dangerous to humans. There are thousands of species of mold and about 16 of the are known as toxic mold which release mycotoxin, a toxic chemical that can cause harm to humans and animals.

Some of the toxic mold species include –

  • Aspergillus
  • Fusarium
  • Paecilomyces
  • Penicillium
  • Stachybotrys
  • Trichoderma

However, not all black mold is toxic. If you suspect that mold somewhere in your house is causing your health problems, then it is advisable to get proper inspection done, to identify the mold species.

Toxic Black Mold Problems and Sick Building Syndrome

Mycotoxins produced from toxic mold is considered to be a major cause of sick building syndrome in places that have unhealthy working conditions. Work places and offices receive less of cleaning attention compared to homes and as a result mold infestations persist for a long time. If you are facing similar problems in your work environment then it might be time to take necessary steps.

The increasing problem of Mold

The problem of mold inside homes is increasing over time. This is partly due to the construction of the buildings and also due to the maintenance done by the home owner. Newer buildings focus more on compact designs and layouts and focus less on ventilation and letting sunlight inside the house.

This causes stagnant air and moisture getting trapped easily inside such constructions leading to favorable conditions for mold growth. Furthermore, home owners are resorting to air conditioners for fresh air instead of their windows. Air conditioners tend to spread the mycotoxins and spores even more indoors and the quality of air is never the same as natural air.

More over the life style of home owners, is becoming busier by the day and people put in lesser time on cleaning their homes.


So the above article should have given you a fair idea about what mold is and how it affects your house and your health. Any kind of organic growth is seen as a symptom of decay and bad energy and should be eliminated from the house at the earliest.

In upcoming articles we shall talk about how to clean and remove mold from your house. If you have any questions or comments, then let us know.



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