Indoor air quality / Ventilation
Oct 30, 2018
The indoor environment within any building is dependent on the complex interaction of numerous factors. These factors typically include:
* the site itself
* the local climate
* contaminant sources
* the building Heating, Ventilation and Air Conditioning (HVAC) system
* building construction techniques
* building occupants
The four primary elements which are typically involved in the development of Indoor Air Quality (IAQ) problems within buildings are:
* Sources of contamination - indoors, outdoors or within the building HVAC system
* The HVAC system - i.e. the performance of the Heating Ventilation and Air Conditioning system
* Contaminant pathways - i.e. the pathways connecting the pollutant/contaminant sources and the building occupants
* Building occupants - i.e. the building population (employees and visitors)
Discussing one element, building occupants:
The term “occupants” applies not only to employees within the building (i.e. who spend the majority of their time within the building) but also to transient visitors and clients. These transient occupants are likely to have different tolerances and expectations from employees and are likely to be more sensitive to odours. Particular groups of occupants are more likely to experience adverse effects from poor IAQ; these include:
- allergy sufferers
- people with respiratory disease
- people with compromised immune systems (chemotherapy, radiotherapy patients)
- contact lens wearers.
It should be remembered that, irrespective of whether or not a person suffers from any of the above conditions, individual susceptibility is highly variable - i.e. one individual may react to a particular IAQ problem whilst those around him/her remain unaffected.
Poor Indoor Air Quality often produces non-specific symptoms in affected persons rather than well defined illnesses. There are two distinct terms associated with employee health concerns and IAQ:
SBS - Sick Building Syndrome:
This term is commonly used to describe symptoms or illness complaints for which no specific cause can be identified. Typical symptoms include headaches, fatigue, sinus congestion, coughing, nasal, eye and throat irritation, increased incidence of colds, skin irritation, dizziness and nausea. Employees generally complain of symptoms only when within the affected building and often express complete relief upon leaving the area. It is however very important to note that these symptoms may not necessarily be caused by poor IAQ - similar health effects may be caused by other environmental stressors including improper lighting, noise, overcrowding, poor ergonomics and job-related psychosocial problems (job stress).
BRI - Building Related Illness:
This term is used to describe incidents where employee illness or health complaints can be directly attributed to IAQ, with a specific illness being diagnosed. The most widely known (although it remains a rare occurrence) example of this is Legionnaires disease - caused by contamination of ventilation systems with Legionella pneumophilia.
Environmental Regulation No. 5 of the Occupational Health and Safety Act No. 85 of 1993, states, inter alia, that an employer must ensure that the air breathed by employees does not endanger their safety and, that prescribed Exposure Limits for airborne substances therein are not exceeded. In addition, an employer is obliged to ensure that every workplace is ventilated either by natural or mechanical means in such a way that:
(a) the air breathed by employees does not endanger their safety
(b) the time weighted average concentration of carbon dioxide, taken over an 8 hour period, therein does not exceed one half per cent by volume (0.5% or 5000 ppm) of air
(c) the carbon dioxide content thereof does not at any time exceed 3% by volume of air.
National Building Regulations, South African National Standard (SANS) 10400: 2011: Any habitable room should be provided with uncontaminated, fresh outside air.
In terms of Regulation 4 (h) of the Facilities Regulations (OHSAct, 85 of 1993); every employer shall ensure that changing rooms are naturally or artificially ventilated in accordance with Part O of the National Building Regulations.
There are currently no established South African legislative requirements for Indoor Air Quality (IAQ) within industrial workplaces. References is therefore made to internationally accepted IAQ guidelines (ASHRAE, OSHA orACGIH)