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Oh for a Breath of Fresh Air!

March 16 2015 - by Dr. David Lee, CLP's Environment Specialist

In the Caribbean, more of our buildings are being air conditioned to make our work environment more comfortable with the intention of making us more productive.  However, sometimes this objective has unintended consequences, and not enough fresh air enters the building. This is especially true for older buildings in which air conditioning units have been retrofitted. In an attempt to increase the efficiency in cooling the building they are hermetically sealed to the extent that in some buildings you cannot open a window.  When there is not enough fresh air available there can be a build-up of carbon dioxide and an increase in particulate matter.  

In indoor spaces occupied by people, the carbon dioxide concentration will reach higher levels than in pure outdoor air - just due to breathing.  The carbon dioxide (CO2) concentration in outdoor air is about 400 parts per million (ppm).  Concentrations of CO2 in indoor air higher than 1,000 ppm will cause discomfort in more than 20% of the occupants, and the discomfort will increase with increasing CO2 concentration.  Discomfort would be expressed in loss of concentration, drowsiness, and a feeling of tiredness and fatigue.  This discomfort will be caused by various gases coming from human respiration and perspiration, and not by the CO2 itself.

At 2,000 ppm carbon dioxide in indoor air, the majority of occupants will feel a significant degree of discomfort, and many will develop nausea and headaches.  Obviously these symptoms would also make the affected occupants less effective and productive in the work place.  While this is not life threatening, it can be very debilitating.  

Particulate matter below 10 microns in size (PM10), otherwise known as respirable particulates, in indoor air quality may cause respiratory distress for some occupants if it exceeds 150 ppm over a 24 hour period - producing flu like symptoms without there being a microbial agent.   Particulates under 2.5 microns (PM2.5) are generally bacteria, fungi and mold and may cause respiratory distress for some occupants if it exceeds 35 ppm over a 24 hour period.  New meters can measure the size of the particles instantaneously, but the organism will still need to be verified in the laboratory.

The lack of fresh air leads to “sick building syndrome”. However, there are a range of solutions that allow fresh air into the buildings depending on the severity of the problem. At fairly low concentrations it might be as simple as opening a window, adding plants to the office (they produce oxygen and remove CO2), making sure the filters on the unit get cleaned every three months (removes particulates), and in the worst cases perhaps putting in fans to bring in fresh air from outside to points that will allow it to be circulated throughout the building.  It helps to be guided by a professional.

Feeling sleepy? Is your productivity low? Are staff members from a particular location in the building always sick with the flu? Are staff members from a particular department falling asleep? It might not be “ethnic fatigue”! Get your indoor air quality tested and maybe all you need is a breath of fresh air!