Achieving a healthy indoor environment by using an emissions barrier for stopping spread of chemicals from building into the indoor air

Pawel

Introduction: 

Airborne particles released from the building construction may be removed by using portable air cleaners with mechanical air filtration (HEPA etc) - Please provide HEPA abbreviation for the clarification. Has been done

Results 1st installation:

Also, the mouldy odour disappeared in the bedroom following the cTrap installation.  Is that a personal statement of the authors? If yes, please indicate that in the paragraph. Has been clarified

General comment: Please keep air concentration unites consistant with the table 1 (µg/m³ not µg/m3). All air concentration unites should ideally be presented or as per ng or µg /m³ for consistency. Has been corrected

Results: 2nd  installation:

There was a disturbing smell inside the building which persisted even after the tar had been removed. If possible, please provide more information about a smell. Has been done

Table 1:

a) n.d. for chloroanisoles. Please provide the abbreviation of n.d. If not detected, please provide a limit of detection (LOD) for this compound. Information has been added

b) The unit of µg/m³  is not applicable for the 'emmisions'  table row but for 'without cTrap' and ' with cTrap' rows. Please modify it for the clarification. Has been corrected

References 

Kolarik, J., and Wargocki P. (2010). Can a photocatalytic air purifier be used to improve the perceived air quality indoors? Indoor Air 20, 255-262. Markowicz, P. and Larsson, L. (2012). The surface emissions trap: A new approach in indoor air purification. J. Microbiol. Methods 91, 290-294.\

Please separate both references Has been done.

Ola

The manuscript proposes unique methodology for isolation/encapsulation of indoor pollution sources if it is impossible or too expensive to remove them. Especially useful when experiencing adverse health effects from moisture damage buildings and when reparation needs to be done quickly. What makes this research very interesting are documented practical interventions in existing troublesome indoor environments, leading to significant improvements in the air quality and symptoms of the tenants.

Introduction, Second paragraph

I really like comprehensive information about indoor air cleaning techniques and harmfulness of devices using UV light and ozone for destroying microorganisms and converting airborne VOCs.

Methods

Some more information/citations about analytical methodology would be appreciated. We have added that the analyses were made by a commercial laboratory viz Eurofins Pegasuslab Ltd, Uppsala, Sweden.

Results 1

Authors mention odour assessment in a few places in the manuscript. It would be interesting to know if they used a special smell validation protocol and how many persons took part in the test. Information has been added.

“The ceiling, walls and floor in the bedroom (as well as the doorway between the bedroom and the living room), but not in the living-room.  were covered with the cTrap cloth.  Subsequently, air sampling for chlorophenols/chloroanisoles was carried out simultaneously in both rooms.”

How long did it take between covering the surfaces with the cTrap and subsequent sampling? Was it an adequate time to reach the equilibrium? It took a few hours. We agree that long term results cannot be evaluated from this experiment; a comment has been added under Discussion.

Results 2

“The air concentrations of PAH were 1726 ng/m3 air. There was a disturbing smell inside the building which persisted even after the tar had been removed. Then, the cTrap cloth was installed on about 75 percent of the wall surface. The smell disappeared and the PAH air concentrations decreased to 139 ng/m3, thus corresponding to a reduction of 92% (Table 1).”

Even tough, the reduction of PAHs concentration is huge, is it enough to justify the installation of the clothe? Please provide exposure limits for occupational conditions or, if possible, indoor environments. Exposure limits differ very much for the different PAH. In general, if the odour complaints disappear then it is assumed that the PAH problem has been solved.

Likewise, for other substances mentioned in the Table 1.

 Results 3

“3 months after cTrap had been installed the air concentration was 1.5 μg /m3 (Table 1), a value which persisted in a follow-up study 6 years after the installation -and the residents still reported no symptoms.”

Long term studies are very much appreciated!

Discussion

Please provide also some more resent references in the first paragraph. Has been done.

An emissions barrier was used in premises with indoor air complaints due to emissions from the buildings in question. The emissions comprised chlorophenols/chloroanisoles and polycyclic aromatic hydrocarbons (PAH) from treated wood, and volatile organic compounds (VOC), mainly 2-ethylhexanol, from PVC flooring and the glue used to paste the flooring onto a concrete slab. Attaching the barrier at the surfaces from where the emissions were spread (floor, walls, ceiling) resulted in a fresh and odour-free indoor air. We conclude that using an emissions barrier in buildings made unhealthy by moisture is an efficient way of restoring a pleasant and healthy indoor air.