Sick Building Syndrome and the Importance of Good Air Quality

We are all familiar with the term ‘Sick Building Syndrome’ as a term that is bandied around to imply an unhealthy environment to be in. But what makes a building ‘sick’? And what are its effects?

Sick Building Syndrome affects the well-being of those who spend time within it. The symptomatic effects are a sore throat, irritated nose/sinus, combined mucous membrane symptoms, tight chest and or wheezing. Not only is this significant for the well-being and therefore satisfaction of the occupants of the buildings, but it can also affect their decision-making skills, productivity and increase absenteeism. Within commercial, office, healthcare and educational settings these can impact on people’s ability to perform daily tasks and can incur huge costs. When staffing costs represent 90% of a businesses operating costs it’s easy to see how the impact of significant staff with low well-being and motivation can be on the profit margins.

There are several factors that need considering when tackling SBS:


According to Finnish researchers there is a significant increase in sick building symptoms when room temperatures are raised from 20 to 24 degrees centigrade in offices or schools. Other international research has shown that sick building symptoms increase in line with rises in temperature.

According to the Health and Safety Executive both air and radiant temperature need to be considered. Radiant temperature (the heat that radiates from a warm object in a space eg the sun; fire; electric fires; ovens; cookers; hot surfaces etc) has a greater influence than air temperature on how we lose or gain heat to the environment.

Carbon Dioxide

According to the University of Technology, Sydney: ‘High levels of CO₂ (above 800 to 1000 parts per million) cause rooms to feel ‘stuffy’. But sick building syndrome-like symptoms can occur at much lower concentrations than this. When CO₂ levels are above 1000 ppm, building occupants can become quite unwell. But this level is uncommon in modern buildings thanks to efficient mechanical ventilation systems.’ However, the Green Business Council Reports that decision-making is 11–23% better at 600ppm than at 1000 ppm despite the latter being seen as an acceptable level.

Poor Ventilation

The Indoor Environment Dept at Berkeley, California has found that ‘increases in the ventilation rates per person among typical office buildings will, on average, significantly reduce the prevalence of SBS symptoms.

Very large increases in ventilation rates, sufficient to reduce indoor CO₂ concentrations to approximately outdoor levels, would be expected to decrease prevalence of selected symptoms by 85%. There is no direct causal link between exposure to CO₂ and SBS symptoms, but rather CO₂ is approximately correlated with other indoor pollutants that may cause SBS symptoms.’

According to the Finnish Society for Indoor Air Quality, ‘Necessary ventilation requires 6 litres per second per person or 3 litres per second per one square metre of floor. At the same time the adjustment of the currents, cleanness of the filters, functioning of the heating units, cleanness of ducts and direction of incoming air should be checked.’

Air Velocity

Air velocity is an important factor in thermal comfort because people are sensitive to the feeling of the air on their skin. The speed of air moving across a person’s skin can help cool them if it is cooler than the environment. However, drafts can occur as a result of ventilation at low temperatures or air leaks within the building.


These can be either detrimental or beneficial depending on the type and origin of the odour e.g. some natural scents can invigorate or relax the occupants of a space whereas noxious smells (from construction and furnishing materials or people) can have adverse affects.


The amount of dust can be reduced using air-filtration and cleaning methods that do not raise the dust into the air.


Relative humidity (ratio between the actual amount of water vapour in the air and the maximum amount of water vapour that the air can hold at that air temperature) should be kept between between 40% and 70% . High humidity environments have a lot of vapour in the air, which prevents the evaporation of sweat from the skin and therefore the body regulating its temperature to cool down. Too much humidity can also encourage mould fungus growth and have negative health effects.

How can we combat the effects of poor indoor air quality?

It has been found that the effect of sick building syndrome is reduced when workers are able to influence the air quality at their workplace. If they can adjust the ventilation or temperatures according to their needs this can diminish symptoms associated with SBS and improve work productivity. According to Carnegie Mellon University natural ventilation or mixed-mode conditioning could achieve 0.8 – 1.3% savings on health costs, 3 – 18% productivity gains, and 47 – 79% in HVAC energy savings.

Improving air-filtering techniques can also be beneficial and this can be approached in a Biophilic manner by incorporating plants and green walls. NASA reports that houseplants requiring low-lighting and carbon plant filters can improve indoor air quality; they remove trace organic pollutants and exposing the root-soil zone removes volatile organic chemicals effectively.

If including several plants or improving the ventilation aren’t options there are some interesting new products that are tackling the issue of air quality such as Bluecher’s Saratech Permasorb – a sheet material you can line the walls with that is filled with tiny spherical balls that suck up and lock in toxins. The Andrea air purifier – an acrylic capsule filtering device which has a plant contained inside claims to be 1000% more effective than a single plant at improving air quality, so if you cannot introduce many plants into your space this one plant could do all the work.

Air quality is one of those areas that many are aware of but few seem to consciously tackle at the design stage, however the implications of poor air quality are clear. What have you done to tackle the issue? Have you measured the CO₂ in your workplace?
Have you experienced a space where the air quality has affected your ability to focus on the task at hand?

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