We more commonly associate feeling ill in our buildings with possible mould, or from gases coming from our indoor furniture and fittings. We attribute infections to close contact with other people.

Yet science is warning us that viral and other infection spread is driven by air pathways (particulate matter highways in effect) in and even between our buildings. We know that pathogenic (infection-causing) bacteria and viruses are found in water damaged buildings, especially after sewage spills, and survive much better under conditions of high humidity. However, these organisms often migrate on air currents to distant parts of a building allowing us to inhale them.

We now understand that the ease at which microorganism move through HVAC and plumbing systems, between close buildings, and even across our building envelope is staggering. Where a bug ends up is not always where it came from, but where it comes from and ends up are both places where we can be exposed to it. Our noses and respiratory tract are designed to trap particles and keep them from our lungs, so they are super-efficient at accumulating microorganisms in those places where infections like colds often starts once we inhale them. Particles that escape these hairs, reach our lungs.

We inhale non-mould particles and gases too and these change things.

Living close to sources of harmful airborne particles from a main road, a waste management facility or a bush fire increases our chances of inhaling pollutants when we are inside our homes or workplaces. Once indoors, these outdoor pollutants have the ability to exaggerate (or in rarer cases reduce) the intensity of our reaction to the indoor contaminants we believed until reading this article were most likely causing our issues; and yes, this particularly applies to outdoor fungal spores, or “mould”, and even their ecologically cooperative or oppositional bacteria.

A high concentration of mould outdoors often translates quickly to a high concentration indoors (remember the staggering movement of air to indoors). So, if you have indoor mould, and already live in a very green area, you will be exposed to a higher concentration than someone by the sea, even though some of those other traffic pollutants may be less of a risk in a remote tropical seaside location.

The current belief that outdoor air is always a robust reference point for healthy air is often inaccurate.

If the physical characteristic (size) of airborne particles allows them to pass into the building, they are also likely to be inhalable and even reach our lungs. The wrong spores from outdoors can make us just a sick as those from indoors, especially if they are coupled to other pollutants.

Comparing indoor to outdoor airborne mould requires a level of understanding and expertise that goes beyond a count under a microscope or a simple threshold. Successful remediation and return to healthy air rely on determining where the mould is likely to have come from, and how significant the mould types are in suggesting that there is water damage in a building.

Most commonly, the introduction of outdoor air is necessary to create and maintain healthy indoor air quality, however there are times when this is not the case. It is just as important to understand our surrounding environment and local sources of pollution and mould outdoors as it is our indoor air when thinking about our health. The source of mould can be better established using cutting edge sampling and analytical technology and an understanding of the external environment, the building airflows, and its physical and mechanical design.

New technologies are emerging that will better define building health.

We believe that an overarching component governing a person’s reactions to indoor air pollutants depends on several factors: including age and pre-existing medical conditions. In some cases, whether a person reacts to a pollutant depends on individual sensitivity, which varies tremendously from person to person, and even with lifestyle. But that reaction also depends on the complex interaction of contaminants from a number of different places.

LITMAS laboratories and consultants proudly hold the highest level Microbiology and Atmospheric Chemistry qualifications and expertise to appraise conditions accurately and reduce errors in our assumptions. They are dedicated through their engagement in preparing Standards and Guideline documents across our key peak bodies, that will craft the future direction of indoor air quality assessments in the future.

We have documented evidence of avoiding under-scoping and over-scoping of remediation projects by ensuring we use a range of well-established scientific metrics. We watch out for the pitfalls and do our best to spot the times when outdoor air is not the gold standard for a healthy building, or where a simple threshold would let us down.

If you need assistance, or just have questions, don’t hesitate to contact us.