Civil Engineering Reference
In-Depth Information
4.3 Air Cleaning
The most advisable approaches to prevent and control poor residential IAQ are the
elimination of sources or the improvement of ventilation effectiveness. If those
methods are insufficient, then air cleaning may be useful (US EPA
2013c
). Air
cleaning devices can be designed to remove PM, gaseous pollutants or both.
Particle filters are used in most HVAC systems in order to protect mechanical
equipment. Those devices are relatively effective in reducing indoor level of
particles and mould spores.
Many cleaning devices for gaseous pollutants use sorbents such as activated
carbon (Godish
2004
). Sorption technology is effective for some chemicals
reviewed in this chapter such as NO
2
and VOCs, but it may produce secondary
pollutants if they react with ozone (Zhang et al.
2011
). Other fan-driven tech-
nologies, such as ultraviolet germicidal irradiation (UVGI), photocatalytic
oxidation (PCO), thermal catalytic oxidation (TCO), plasma, botanic air cleaners,
ion generators, and electrostatic precipitators were reviewed and the conclusion
was that the efficiency of each cleaner depends on the indoor air pollutants. Hence,
air cleaners should be selected depending on the indoor pollutant to be removed
and the degree of elimination needed (US EPA
2013c
).
5 Conclusions and Perspectives
Indoor concentrations of the pollutants covered in this chapter are in general
higher than outdoors, both in buildings used as workplaces and in residences. The
guideline values set by WHO are frequently exceed indoors and, hence, IAQ
regulation policies should be considered as well as outdoors. The elimination of
indoor sources and the improvement of ventilation effectiveness are the most
advisable methods to prevent and control poor IAQ, but if they result inadequate,
then air cleaning may be useful.
Short-term and long-term effects of individual indoor air pollutants have been
described. Nevertheless, there are significant gaps on long-term exposures to low
concentrations and mixtures of different pollutants. Environmental factors may
affect health simultaneously and synergistically, which makes complicate to
estimate whether certain health effects are exclusively due to indoor air pollution.
Even for the most comprehensive research on IAQ, it is complicated to establish a
clear relationship between the characteristics and composition of indoor air and the
health and welfare of the occupants. Further research on the field is need and,
furthermore, multidisciplinary collaboration is required to address IAQ problems.
