ASHRAE Journal - September 2019 - 80

COLUMN PRODUCTIVITY-CIBSE

Photocatalytic removal using titanium dioxide. This
has been studied for many years to address a range of
pollutants, with potential indoor and outdoor applications including paints or wall coverings and internal
duct surfaces. A recent independent comprehensive
review6 on its potential to reduce NOx levels concluded
there is little evidence of impact in outdoor applications,
or the impact would be very small and require very large
exposed areas; it does appear to reduce NOx levels when
applied indoors, but there remains much uncertainty
as to other possible consequences-for example, other
hazardous pollutants such as ozone may be generated
from the photocatalytic decomposition of NOx and other
air pollutants.
VOC-reducing materials. A number of claims are
being made about materials that may help reduce
indoor VOC levels, typically either by absorbing or
decomposing them. One example is wool, which has
been shown to have VOC absorbent properties. The
extent would depend on the type of wool, and the
air would need to be in contact with the wool, which

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implies applications for furniture, floor and wall coverings rather than insulation.7 The body of evidence is not
yet substantial and the effect may be small, but longstanding historic applications mean there is little risk of
unintended consequence. Other new products claim to
decompose VOCs into "inert products" that would then
be either released into the air or bound to the product
in question; however, there is little public data on the
mechanisms and by-products, and claims should be
examined carefully.

Conclusions
An important conclusion from this evolving field is
to follow the precautionary principle and apply source
control, as some effects on health many only manifest
themselves in the long-term, as in case of asbestos
and lead paint. This does not prevent innovation, but
requires a cautious review of claims, possible effects,
and monitoring and evaluation so as to keep new uses
under review.
Further articles in the next few months will cover
other topics, including housing refurbishment and its
impact on comfort, air quality, humidity and energy
consumption; and air quality monitoring procedures
and equipment.

References
1. NICE. 2019 Forthcoming. "Indoor air quality at home."
https://www.nice.org.uk/guidance/indevelopment/gid-ng10022/
consultation/html-content-2.
2. WHO. 2009. "Guidelines for indoor air quality: dampness and
mould," World Health Organization.
3. WHO. 2005. "Electromagnetic fields and public health-
Electromagnetic hypersensitivity, Backgrounder." December.
4. SCENIHR. 2015. "Opinion on Potential health effects of
exposure to electromagnetic fields (EMF)." European Commission.
5. Cullinan P. 2016. Building health and ill-health, Presentation
at annual BSRIA Briefing, November 2016, London.

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6. Defra and Air Quality Expert Group. 2016. "Paints and
Surfaces for the Removal of Nitrogen Oxides." Prepared for:
Department for Environment, Food and Rural Affairs; Scottish
Government; Welsh Government; and Department of the
Environment in Northern Ireland, Crown.
7. Mansour E., R. Marriott, G. Ormondroyd. 2016. "Sheep wool
insulation for the absorption of volatile organic compounds." Young
Researchers' Forum III Innovation in Construction Materials.
8. Godefroy, J. 2019. "A rigorous exercise." CIBSE Journal: Health
and Wellbeing Special. June.
9. Fisk, W., P. Wargocki,X. Zhang. 2019. "Do indoor CO2 levels
directly affect perceived air quality, health, or work performance?"
ASHRAE Journal 61(9).

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ASHRAE Journal - September 2019

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