Highlights from Healthy Buildings 2012

Friday 27 July, 2012

Indoor Air Contaminants – New Findings:


Secondary emissions are now a concern. Re-emission of VOCs absorbed onto carpet and ceiling tiles occurs long after the new-office odours have gone. Short-term VOC emissions during construction turn into long-term emissions.

A number of mortars and screeds have been shown to emit significant amounts of toxic VOCs following curing, originating from product additives.

NOX from Tri-gen plants ends up in indoor air

Without gaseous filtration on air intake, nitrous oxides, including the harmful nitrogen dioxide can end up back within a building at levels that can be dangerous to human health. A more considered and holistic approach is required when implementing trigeneration systems, and this should involve a risk assessment of the site and the occupants.

Ultra-fine particles, less than 100 nanometres

Numerous international papers presented covering source and behaviour under different indoor conditions. Currently unregulated and much smaller than the regulated PM10 and PM2.5  dust classifications. From outdoor sources such as cars and indoor sources such as laser printers.


Increasingly added to many new building materials and furniture. New studies on the behaviour of nano-material dust in indoor air under different building operating conditions.

Semi-Volatile Organic Compounds (SVOCs)

Some SVOCs are human endocrine disruptors including:

  • Phthalates plasticisers, used in plastics
  • Fire retardants added to building materials, such as PCBs. Concrete adjacent to gap sealants or insulation can ‘soak’ up the fire retardants then release them into the indoor air over time.
  • Pesticides

SVOCs are very persistent in the indoor environment, staying around for years. Now exposures are correlated with common human diseases.

Secondary Organic Aerosols (SOA)

SOA are formed from oxidation of common VOCs.  Many cases covered, for example limonene (lemon extract used in most cleaning products) is broken down by ozone or photooxidation, is has been shown to form other significantly more toxic secondary products.


Sneezed saliva particles can now be modelled in detail using CFD.
Most exposure occurs in air, rather than surface contact, showing the importance of adequate ventilation and indoor air filtration.