Mitigation of indoor pollution events by lime-cement plasters: Full-scale assessment

The assessment of the impact of passive remediation approaches to improve indoor air quality requires the realscale investigation of technologies. Plasters are identified as relevant materials to mitigate indoor pollution. Interestingly, lime-cement plasters can be formulated with activated carbon sorbent to expand their uptake properties. This work provides a full-scale and replicable evaluation methodology to address the passive remediation properties of materials with regard to experimental facilities and the diversity of pollution scenarios. This methodology is applied to lime-cement plaster formulated or otherwise with activated carbon and subsequently set in IRINA experimental room (40 m3). Both materials are successively submitted to CO2, ozone and VOC transient pollution events. Specific attention is paid to the behaviour of formaldehyde. First, both fresh plasters demonstrate high mitigation capacities towards CO2. This behaviour has to be compared to the ageing of materials. Similarly, excellent decomposition capacities are evidenced towards ozone. Both pollution scenarios highlight a higher mitigation of lime-cement compared to activated carbon. Regarding VOC pollution scenarios, the effective removal of formaldehyde is evidenced. However, formaldehyde decay follows second-order kinetics, due to surface reactive processes, preventing the calculation of the clean air delivery rate (CADR). Mitigation of other VOCs is considerably promoted by activated carbon in the plaster. Abatement of different classes of pollutants is discussed taking CADR into consideration. Results evidence the effectiveness of combining carbonbased sorbent with plaster in order to benefit from complementary uptake properties. Finally, the CADR of selected pollutants are compared with classically determined equivalent data for active remediation technologies. This full-scale comparison demonstrates that passive mitigation approaches offer equivalent remediation capacities compared to widespread active and destructive air treatment technologies.