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You are here: Home / Archives for Fungi

Can Smelling Mold In The Air Include Mold Spores?

Jackson Kung'u

The person who asked this question probably wanted to know whether if one smells “earthy” or “musty” odours associated with mold, they would also be inhaling mold spores. The fact is we inhale some mold spores all the time. During summer, for example, we inhale more spores from outdoor air than from indoor air. However, in a building with mold growth problems airborne spores could be excessively high.

Smelling “musty” or “earthy” odours does not necessarily mean one is inhaling high levels of mold spores. While the smell could be due to microbial volatile organic compounds (usually abbreviated as MVOCs), some volatile organic compounds are not of microbial origin. Also, one of the MVOCs responsible for the “earthy” smell is geosmin. This compound is produced by not only molds but also by actinomycetes and other bacteria. Therefore, while the presence of VOCs may be an indication of hidden microbial contamination, they may not be a reliable indicator of microbial contamination or contamination by a specific microorganism.

Filed Under: Fungi, Indoor Air Quality Tagged With: microbial volatile organic compounds, mold growth, mold spores, MVOCs

What Are Acceptable Levels Of Mould Spores And What Are The Effects Of Spores On The Human Body?

Jackson Kung'u

After analysing air samples for total spore counts, we often get asked whether there are acceptable levels of mould concentrations in air and what effects mould spores have on human health. Unlike many other indoor pollutants, there are currently no set acceptable levels for mould spores. The scientific community including medical doctors is polarized on the effects of mould on human health. However, it is generally accepted that mould can:

  • Elicit allergic reactions to sensitized (or atopic) individuals and that not all moulds are allergenic
  • Infect humans especially those with weak immune systems
  • Produce toxic metabolites (mycotoxins) that can kill or cause other complications if ingested in food.

While scientific evidence to prove that mould is the cause of some illnesses is lacking, there is enough evidence to support the need to remove mould from occupied environments.

Filed Under: Fungi, Indoor Air Quality Tagged With: health risks, mould allergy, mould spores, mycotoxins

Why Do Some People Get Sick From Mould And Others Do Not?

Jackson Kung'u

Why do some people get sick from mould and others do not? It is because of genetic and physiological differences. Sensitivity to mould in about 20 % of the human population is believed to be hereditary. Other factors that influence individual’s resistance to mould include age and general health status. For example, infants, the elderly and those recovering from diseases may be at risk of mould exposure even at levels that would otherwise be considered “normal”.

Susceptibility differences among individuals and the variability of moulds in their ability to cause health problems make it difficult to determine and set permissible exposure levels for indoor moulds.

Filed Under: Fungi, Indoor Air Quality Tagged With: mould, mould exposure

Can You Paint Over Mould On The Shower Ceiling?

Jackson Kung'u

Recently we were asked whether it would be OK to paint over mould on the shower ceiling. Painting over existing mould is probably not a good idea because the mould may continue growing beneath the paint film and subsequently the paint would start peeling off. The best solution would be to clean the mould following current mould remediation guidelines such as CCA 82 – Mould Guidelines for the Canadian Construction Industry and then find a way of reducing condensation in the shower. Painting after the mould has been cleaned and the condensation problems fixed would be OK.

Filed Under: Fungi, Mold Tagged With: mould, mould growth, Mould Remediation

My Interest In The Study Of Fungi.

Jackson Kung'u

I have always been fascinated by fungi. Fungi are a group of organisms to which moulds (mildews), yeasts, and mushrooms belong. Fungi used to be classified under the plant kingdom. However, they differ from plants in that they cannot make their own food and their cell wall is mainly made of chitin and glucan and not cellulose. Since they cannot make their own food, fungi have to survive as either saprophytes, parasites (pathogens) or by forming symbiotic relationships with their hosts. Saprophytic moulds are the ones commonly found in indoor environment growing on wall surfaces and other organic substrates. It is estimated that there are close to 1.5 million species of fungi but only about 100,000 species have been described.

Entomosporium spores
Entomosporium spores

My interest in fungi started when I completed my B.Sc. (Agriculture) and got employed as a plant pathologist. As a trainee plant pathologist, I spent countless hours in a plant clinic where farmers brought their diseased plants for diagnoses. My first fungus to identify without help was Entomosporium. One feature that makes me remember this fungus is the shape of the spores. The spores have appendages that make them resemble insects or two-legged mice with legs stretched sideways. I also went out into the field collecting diseased plants and taking them back to the laboratory for disease diagnoses and preservation as reference material. Working with diseased plants is not always easy because they won’t tell you where it is hurting (if at all they feel pain). You have to depend on symptoms and laboratory culturing and identification of the causative agent. If a plant is just wilting, for example, it is had to tell the cause of wilting which could be due to fungi, nematodes, bacteria, physical/chemical or physiological factors that interfere with water movement in the plant.

In my early days as a trainee, one challenge I had was to isolate the disease causing agent and getting pure cultures of the mould. It was not always easy because of the myriad saprophytic moulds and bacteria present on the surfaces of the plant. However, I learned quickly some clever ways plant pathologists and mycologists have developed to overcome the problem of contamination.

I was fortunate to be taught and interact with some of the world authorities in Mycology at CABI Bioscience (formerly the International Mycological Institute) and the University of Kent in the United Kingdom. These great people made me to like the subject.

My interest in fungi is now focused on indoor moulds. Indoor moulds are recognized health hazards and it is estimated that 20% of human population is sensitive to mould exposure. It is also believed that long-term exposure to mould could lead to sensitization.

Filed Under: Fungi Tagged With: Fungi, mildews, moulds, yeasts

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Salmonella food poisoning and symptoms

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