Toxicity Issues: Indoor Air Quality - Nearly Zero Energy Building Refurbishment - page 345

For example, indoor formaldehyde can be kept at low levels by avoiding the use
of formaldehyde-emitting materials, such as particleboard and plywood. Instead,
softwood plywood and oriented-strand boards may be used (Godish 2004 ). Even
though the tendency is to reduce or remove some VOCs from building products,
building materials contain an increasing number of chemicals that can emit
reactive compounds or lead to the production of secondary pollutants that con-
tribute to poor IAQ (Uhde and Salthammer 2007 ). For instance, primary sources of
formaldehyde may be completely removed but it may be found indoors, since
formaldehyde is the major oxidation product of household products containing
VOCs (Destaillats et al. 2006 ).
Emissions of VOCs from building materials are significant during the first six
months. Carbonyls and ketones followed by aromatics are the compounds that
mainly contribute to the indoor air concentrations (Missia et al. 2010 ). In order to
prevent adverse health effects after decoration, refurbishment or renovation of a
building, some authors recommend a wait period before using newly refurbished
rooms in public buildings, especially for those used by risk groups like young
children such as nurseries (Herbarth and Matysik 2010 ). Remediation of dampness
and mould has been reported to reduce respiratory diseases, especially concerning
adults since there is little evidence for children (WHO 2009 ).
Indoor sources can also be treated or modified. For example, formaldehyde-
emitting surfaces can be treated with coatings, and asbestos-containing materials
can be encapsulated to prevent fibre release. Emissions of combustion by-products,
such as CO, NO 2 , particles, PAHs and VOCs may be reduced by means of
amending and replacing malfunctioning combustion devices used for cooking and
heating purposes (Godish 2004 ).
4.2 Ventilation and Infiltration Improvements
The concentration of indoor air pollutants can be lowered by increasing the
ventilation rate and its effectiveness. Ventilation is essential for maintaining
comfortable, low-human-odour-building environments and helps to increase
indoor air circulation. Apart from decreasing the concentration of indoor pollu-
tants, increasing ventilation rates also reduces the time available for indoor
chemical reactions, such as the ones between indoor ozone and VOCs which may
produce substances that often are more irritating than their precursors (Weschler
and Shields 1997 ). It is also advisable to increase ventilation rates during indoor
activities such as painting, cooking, cleaning and smoking (US EPA 2013c ).
The correct design of the infiltration system is a key factor in the control of
some indoor pollutants such as radon. Measures include the sealing of foundation
cracks and other openings, the depressurisation of the soil around the building, the
installation of barriers and membranes and, finally the adequately ventilation of
unoccupied and occupied spaces (Pacheco-Torgal, 2012 ).