GAS DETECTION & MONITORING
SEEKING QUALITY
João Marcos Dyer, Geo-Environmental Consultant from Ground-Gas Solutions, explains Sick Building Syndrome (SBS) and highlights the importance of maintaining good indoor air quality in workplace.
Maintaining good indoor air quality is critical when ensuring a safe and comfortable working environment for building occupants. Poor indoor air quality can lead to Sick Building Syndrome, SBS, which causes a loss of concentration, fatigue, headaches, breathing difficulties and nausea.
SBS can lead to low productivity and staff absences, especially those with existing medical conditions such as asthma. Typical causes of poor indoor air quality include over-crowding, inadequate ventilation, contaminants originating from certain types of building materials, volatile organic compounds, particulate matter and radon. Each of these poses a different health risk and so reinforces the importance of identifying the cause of poor indoor air quality in order to put in place the correct measures.
In order to assess indoor air quality and determine whether or not there is a health risk, monitoring and sampling of indoor air needs to be undertaken. Once the indoor air quality has been assessed the results can be compared against existing guidelines, such as the Health and Safety Executive EH40/2005 Workplace exposure
limits. Appropriate measures can then be put in place to either maintain and/ or improve the indoor air quality to a level that provides a, healthy and safe working environment.
UK and international thresholds and limits, particularly in the workplace, vary significantly. The US Environmental Protection Agency and the US National Institute for Occupational Safety and Health state that peak carbon dioxide concentrations over 1,000ppm are an indicator of poor air quality.
Whereas the American Society of Heating, Refrigerating and Air- Conditioning Engineers Standard 62-2001 sets an indoor guideline for carbon dioxide at no greater than 700ppm (0.07% v/v) above outdoor air levels. Therefore, with current background atmospheric concentrations around 400ppm, if a building occupier is in a space that encounters levels greater than approximately 1,100ppm they are likely to experience some of the symptoms associated with SBS.
The graph below illustrates monitoring undertaken by GGS in an
office building in Manchester, showing a week-long snapshot of the carbon dioxide concentrations within one of the open plan offices.
Although the carbon dioxide concentrations do not exceed the EH40/2005 guidelines for workplace exposure limits, there are daily peaks in carbon dioxide concentrations between 1,100 and 1,400ppm during daytime working hours when the office was fully occupied by staff, meaning that some staff may have experienced early symptoms of SBS during these periods.
The source of carbon dioxide was most likely from the occupiers of the building from the natural process of breathing. The building’s ventilation system however did not appear to be sufficiently circulating enough fresh air in order to maintain carbon dioxide concentration at a comfortable level during working hours. Importantly it was found that carbon dioxide concentrations were not returning to background atmospheric concentrations overnight.
In a bid to address the issue the clients implemented a range of improvements to the current air conditioning and heating system. The monitoring and sampling strategy undertaken by GGS at the site ensured that the indoor air quality was assessed efficiently, allowing steps to be taken quickly by the occupiers. This ultimately led to a reduction in staff sickness and an improvement in staff efficiency.
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