Getting to grips with IAQ issues

Problems with indoor air quality are preventable, asserts WILLIAM BOOTH.The World Health Organisation states that the definition of health is: ‘A state of complete well-being and not merely the absence of disease,’ (WHO 2000) and, ‘The human right to a healthy indoor environment includes the right to breathe clean air, the right to thermal comfort and the right to visual health and visual comfort.’ The outbreak of pandemic diseases such as SARS and the increased publicity of MRSA in hospitals have increased public awareness of the role that air quality has to play regarding health issues. There is a growing realisation that adverse affects on health could be caused by poor air quality. Important issue Indoor air quality (IAQ) has become an important occupational health-and-safety issue. People working indoors often experience headaches, shortness of breath, coughing or other symptoms. Those people who are more sensitive or more exposed will often experience symptoms earlier than others. However, without an appropriate assessment of indoor air quality it is difficult to prove that these symptoms are due to a particular indoor air contaminant or range of contaminants. Feelings of discomfort and illness may be related to a variety of causes including noise levels, thermal comfort (inadequate control of temperature, humidity and/or inappropriate air movement), lighting, chemicals, dusts, moulds, bacteria, vapours and odours. There is some evidence that there is an inverse relationship between fresh-air ventilation rates and sick-leave rates in office buildings. The Health & Safety at Work Regulations state that the workplace should be maintained in an efficient state with suitable services to support the business operation. IAQ and ventilation It is worth considering the background to IAQ and ventilation before turning to how to tackle IAQ issues. Part F (Ventilation) of the Building Regulations has been subject to review, resulting in the July 2004 consultation package. Part F deals with ventilation of buildings — both domestic and other types. The initial impact can only be small as Part F will be applied to new build. As time goes by, a larger proportion of the UK building stock will be influenced. Nevertheless, it is important to be aware of its objectives with regard to indoor air quality. As with most guidance, design values and strategies are set to minimise hazards — in this case from inadequate ventilation. The specific hazards related to inadequate ventilation are: • hygrothermal conditions; • fungal growth; • house dust mites; n gaseous combustion products, e.g. carbon monoxide (CO), oxides of nitrogen (NOx) and sulphur dioxide (SO2); • environmental tobacco smoke; • volatile organic compounds (VOCs); • radon, landfill gas and other hazardous soil gases. General guidance of Part F (Section 0) sets out the purpose of ventilation, the types of ventilation and its control. Part F has now adopted a performance-based approach rather than the ‘one-size-fits-all’ approach used previously. Part L of the Building Regulations governs the building fabric, and its intention is to reduce the proportion of leaky buildings rather than to move towards very airtight buildings. The reduction in air infiltration (i.e. uncontrollable air exchange) is compensated for by purpose-provided ventilation specified in Part F). For domestic dwellings, a prime target is to keep relative humidity below 70% to control moisture levels to minimise fungal growth. It is important to realise that this is dealt with by local extract ventilation and by whole-house ventilation. For other buildings (including offices), it is proposed to increase the minimum fresh-air flowrate from 8 to 10 l/s per person. Photocopiers, operated more than 30 minutes an hour, will require local extract ventilation at a rate specified per unit. Part F (Clause 0.20) refers to source control as a complementary strategy for achieving good IAQ. Part F will apply to new build (including extensions) and to replacement windows in older buildings. Site investigations It is convenient to adopt the generic philosophy and strategies set out in Part F when dealing with IAQ problems. In reality, life is not straightforward, but a methodical and logical approach can only pay dividends. IAQ issues will affect many buildings. IAQ problems can be due to interactions between building materials and furnishing, activities within the building, outdoor environment, and building occupants. Contaminants can originate within the building or be drawn in from outside. IAQ problems can arise when specific or multiple contaminant concentrations become excessive. This can happen even if the HVAC system is properly functioning. It is important to establish whether or not the source of the problem lies wholly within the building. Changes to furnishings, IT equipment and cabling as well as routine decoration and painting can all be triggers. The resolution revolves around three factors: minimising the size of the pollution source; • maximising the degree of local extract (i.e. capture);  providing adequate dilution ventilation. Clearly, capital and running costs have to be taken into account. Maintaining a healthy and comfortable indoor environment in any building requires integrating many components of a complex system. IAQ problems are preventable and solvable. Given the complex potential causes of IAQ problems in buildings, those responsible for building-services specification, design and maintenance will need to call on specialist assistance — either as a positive policy or a positive response to genuine complaints. BSRIA can assist the professionals in both cases with site investigations. Summary The importance of taking notice of genuine complaints about IAQ in the workplace cannot be over emphasised. It is important to investigate complaints and understand how you can obtain an understanding of the operating characteristics of the indoor environment. BSRIA has extensive experience in dealing with real-life IAQ problems and provides expert services to support FM professionals. William Booth is head of site investigation and physical modelling at BSRIA MicroClimate, Old Bracknell Lane West, Bracknell, Berks RG12 7AH.
microclimate@bsria.co.uk



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