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Increased levels of bacterial markers and CO2 in occupied school rooms

Fox, A; Harley, W; Feigley, C; Salzberg, D; Sebastian, Aleksandra LU and Larsson, Lennart LU (2003) In Journal of Environmental Monitoring 5(2). p.246-252
Abstract
Our group previously demonstrated that carbon dioxide (CO2) levels in heavily occupied schools correlate with the levels of airborne bacterial markers. Since CO2 is derived from the room occupants, it was hypothesized that in schools, bacterial markers may be primarily increased in indoor air because of the presence of children: directly from skin microflora or indirectly, by stirring up dust from carpets and other sources. The purpose of this project was to test the hypothesis. Muramic acid (Mur) is found in almost all bacteria whereas 3-hydroxy fatty acids (3-OH FAs) are found only in Gram-negative bacteria. Thus Mur and 3-OH FA serve as markers to assess bacterial levels in indoor air (pmol m-3). In our previous school studies, airborne... (More)
Our group previously demonstrated that carbon dioxide (CO2) levels in heavily occupied schools correlate with the levels of airborne bacterial markers. Since CO2 is derived from the room occupants, it was hypothesized that in schools, bacterial markers may be primarily increased in indoor air because of the presence of children: directly from skin microflora or indirectly, by stirring up dust from carpets and other sources. The purpose of this project was to test the hypothesis. Muramic acid (Mur) is found in almost all bacteria whereas 3-hydroxy fatty acids (3-OH FAs) are found only in Gram-negative bacteria. Thus Mur and 3-OH FA serve as markers to assess bacterial levels in indoor air (pmol m-3). In our previous school studies, airborne dust was collected only from occupied rooms. However, in the present study, additional dust samples were collected from the same rooms each weekend when unoccupied. Samples were also collected from outside air. The levels of dust, Mur and Cu-10:0, C-12:0, C-14:0, and C-16:0 3-OH FAs were each much higher (range 5 50 fod) in occupied rooms than in unoccupied school rooms. Levels in outdoor air were much lower than that of indoor air from occupied classrooms and higher than the levels in the same rooms when unoccupied. The mean CO2 concentrations were around 420 parts per million (ppm) in unoccupied rooms and outside air: and they ranged from 1017 to 1736 ppm in occupied rooms, regularly exceeding 800-1000 ppm, which are the maximum levels indicative of adequate indoor ventilation. This indicates that the children were responsible for the increased levels of bacterial markers. However, the concentration of Mur in dust was also 6 fold higher in occupied rooms (116.5 versus 18.2 pmole mg(-1)). This further suggests that airborne dust present in occupied and unoccupied rooms is quite distinct. In conclusion in unoccupied rooms, the dust was of environmental origin but the children were the primary source in occupied rooms. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Environmental Monitoring
volume
5
issue
2
pages
246 - 252
publisher
Royal Society of Chemistry
external identifiers
  • pmid:12729263
  • wos:000182392700018
  • scopus:0037395488
ISSN
1464-0325
DOI
language
English
LU publication?
yes
id
fe0a81b0-7d34-4d93-8971-73416c8e56e0 (old id 313024)
date added to LUP
2007-09-03 08:39:11
date last changed
2018-05-29 11:15:41
@article{fe0a81b0-7d34-4d93-8971-73416c8e56e0,
  abstract     = {Our group previously demonstrated that carbon dioxide (CO2) levels in heavily occupied schools correlate with the levels of airborne bacterial markers. Since CO2 is derived from the room occupants, it was hypothesized that in schools, bacterial markers may be primarily increased in indoor air because of the presence of children: directly from skin microflora or indirectly, by stirring up dust from carpets and other sources. The purpose of this project was to test the hypothesis. Muramic acid (Mur) is found in almost all bacteria whereas 3-hydroxy fatty acids (3-OH FAs) are found only in Gram-negative bacteria. Thus Mur and 3-OH FA serve as markers to assess bacterial levels in indoor air (pmol m-3). In our previous school studies, airborne dust was collected only from occupied rooms. However, in the present study, additional dust samples were collected from the same rooms each weekend when unoccupied. Samples were also collected from outside air. The levels of dust, Mur and Cu-10:0, C-12:0, C-14:0, and C-16:0 3-OH FAs were each much higher (range 5 50 fod) in occupied rooms than in unoccupied school rooms. Levels in outdoor air were much lower than that of indoor air from occupied classrooms and higher than the levels in the same rooms when unoccupied. The mean CO2 concentrations were around 420 parts per million (ppm) in unoccupied rooms and outside air: and they ranged from 1017 to 1736 ppm in occupied rooms, regularly exceeding 800-1000 ppm, which are the maximum levels indicative of adequate indoor ventilation. This indicates that the children were responsible for the increased levels of bacterial markers. However, the concentration of Mur in dust was also 6 fold higher in occupied rooms (116.5 versus 18.2 pmole mg(-1)). This further suggests that airborne dust present in occupied and unoccupied rooms is quite distinct. In conclusion in unoccupied rooms, the dust was of environmental origin but the children were the primary source in occupied rooms.},
  author       = {Fox, A and Harley, W and Feigley, C and Salzberg, D and Sebastian, Aleksandra and Larsson, Lennart},
  issn         = {1464-0325},
  language     = {eng},
  number       = {2},
  pages        = {246--252},
  publisher    = {Royal Society of Chemistry},
  series       = {Journal of Environmental Monitoring},
  title        = {Increased levels of bacterial markers and CO2 in occupied school rooms},
  url          = {http://dx.doi.org/},
  volume       = {5},
  year         = {2003},
}