Indoor air quality (IAQ) is a key component of employee productivity. IAQ describes one or all of several parameters (see side boxes for more detail):

• Comfort index (temperature, relative humidity, air ventilation and exchange);
• Moulds and other fungi;
• Gases (carbon dioxide, carbon monoxide, NOx);
• Volatile organic compounds (VOC’s); and.
• Particulate matter (respirable and particulate).

Poor air quality can lead to employee fatigue and extended loss of time through sickness or disability. By monitoring and advising a building owner or operator, OCL Group, can work with a Client to provide an optimum working environment.

OCL Group has conducted indoor air quality investigations since 1982. Our project experience has included all types of buildings: hospitals, schools, office buildings, commercial spaces, call centres, court facilities and residences. We combine a broad range of skills and expertise to advise the Client on the indoor air as a system not just providing measurements. We can also work with employees and Joint Occupational Health & Safety Committees to explain work programs and results of investigations.

Please refer to the attached PDF files for some examples of recent projects.

For further information on indoor air quality:

• American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE). Standard 55-1992. Thermal Environmental Conditions for Human Occupancy.
• American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE). Standard 62.1-2004. Ventilation for Acceptable Indoor Air Quality.
• Brooks, B.O. and W. F. Davis. 1992. Understanding Indoor Air Quality. (CRC Press. ISBN 0-8493-8846-5).
• Canada Mortgage & Housing Corp. (CMHC/SCHL). 1995. Building Materials for the Environmentally Hypersensitive. (ISBN.0-662-21107-3).
• Hansen, S.J. 1991. Managing Indoor Air Quality (Fairmount Press Inc./Prentice Hall Publ. ISBN 0-13-553124-1).
• Health Canada. Indoor Air Quality in Office Buildings: A Technical Guide. (Publ. 93-EHD-166. Revised 1995).
• Meckler, M. 1996. Improving Indoor Air Quality Through Design, Operation and Maintenance. (Fairmount Press Inc./Prentice Hall Publ. ISBN 0-13-231820-2).
• Maroni, M., B. Seifert and T. Lindvall. 1995. Indoor Air Quality: A Comprehensive Reference Book. Air Quality Monographs Vol. 3. Elsevier Publ. ISBN 0-444-81642-9.
• National Academies of Science/Institute of Medicine. 2004. Damp Indoor Spaces and Health. (National Academies Press, ISBN 0-309-09193-4).
• O’Reilly, J.T., P. Hagan, R. Gots and A. Hedge. 1998. Keeping Buildings Healthy: How To Monitor and Prevent Indoor Environmental Problems. (Wiley Interscience. ISBN 0-471-29228).
• Samson, R.A., B. Flannigan, M.E. Flannigan, A.P.Verhoeff, O.C.G. Adan and E.S. Hoekstra. 1994. Health Implications of Fungi In Indoor Environments. Air Quality Monographs Vol. 2. (Elsevier Publ. ISBN 0-444-81997-5).
  

Comfort Index

For most buildings with a mechanical ventilation system, the primary operating criterion is Comfort Index. Because each occupant or worker is unique, with their own sense of what makes them comfortable, it is not possible to specify a single temperature or relative humidity, but rather a range of conditions. This is further complicated by a suite of “related factors”, including temperature gradients (cold floors/hot ceiling), drafts, radiant heat (particularly exposed sunlight) and activity level. Optimum conditions are described in American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) Standard 55-1992.

Comfort ranges for temperature are 20-25 oC and 30-70% for relative humidity. For most Canadian buildings, the lower end of these ranges is more typical; in winter, it is very difficult to achieve higher than 30% relative humidity, even with a humidification system. Care has to be taken with conditions of relative humidity above 50% due to the high potential for surface condensation, particularly in carpeting on concrete floors, with the resultant likelihood of mould contamination.

The generally accepted measures for air freshness are Carbon Dioxide (CO2) and Carbon Monoxide (CO). Carbon dioxide is a natural component of breathing. The content of non-polluted outside air is 350-400 ppm; the content of indoor air is typically 800-1000 ppm, depending on the number of people, the ventilation rate and level of activity within an area. Carbon monoxide is a by-product of combustion, such as vehicle exhaust. It is often present in indoor air, due to fugitive entry from idling vehicles near air intakes. Good air movement and circulation, without drafts, contributes to the sense of freshness in an occupied space.

In accordance with the revised ASHRAE Standard 62.1-2004, comfort (including odour) criteria with respect to human bio-effluents are likely to be satisfied if the ventilation results in indoor carbon dioxide concentrations, which are no more than 700 ppm greater than the outdoor level. Ventilation rates (including the fresh air fraction) and number of air changes/hour are also specified in this standard. With respect to carbon monoxide, Standard 62.1-2004 sets an upper limit of less than 11 ppm Time-Weighted Average (TWA) for Carbon Monoxide, but current recommendations set levels at less than 4 ppm.

Moulds

Moulds are ubiquitous in the outdoor environment. Depending on the location and season, concentrations of air-borne moulds can be very high, often resulting in complaints of “hay fever” or “summer time allergies”. If a building is ventilated by operable windows, mould concentrations and species diversity should be approximately the same comparing outdoor and indoors. However, if air-borne concentrations are much higher or only one or two species are dominant, then mould contamination has occurred. In mechanically-ventilated buildings, a filtration system limits the entry of moulds. In such buildings, mould concentrations are expected to be lower than outdoors. However, in cases where the air-borne concentrations are higher than outdoors or only a few species are dominant, then mould contamination is occurring.

Moulds grow in locations that provide food, warmth and moisture. The key feature is moisture. Most moulds grow best in conditions of greater than 60% relative humidity. This can be achieved in even very dry environments at sites of condensation as on a cold beam, outdoor wall or basement floor. Food for many moulds is cellulose (e.g., drywall covering, wallpaper, wallpaper glue, documents/boxes/paper and ceiling tiles). Moulds release spores and other fragments and give off exudates or volatile organic compounds. Depending on the types of moulds and conditions, the releases and exudates can create a very bad environment for occupants. Responses can range from allergy like rhinitis to headaches, nausea and general feeling of “not well”.

OCL Group has the necessary equipment and expertise to assess visible and hidden mould contamination, to advise on appropriate remedial activities and to supervise/monitor remediation to ensure appropriate conditions are met.