For VOCs, the results point towards significant contribution from home and office microenvironments, since both of them were present in 90th percentile + and –.
Differences in the 90th + percentile for some of the compounds were found across the microenvironments (Appendix 9). A major number of compounds were found for street microenvironments (which includes walk, bike or stand) rather than for the rest of the commute transports. Car compounds were similar to the street, however, compounds such cumene, dipentene, and thrimethylbenzenes were not observed at the 90th + percentile. Cars are more associated with BTEX compounds (Golhosseini et al., 2013) and higher concentrations were displayed for more volatiles compounds like
146 ethylbenzene, p,m, o-xylene and pyridine at bus transport mode, compounds that had been reported emitted higher concentration during the bus commute (Lau and Chan, 2003, D'Souza et al., 2009), while for train, the opposite trend was present; displaying the higher concentration in the less volatile compounds such cumene, dipentene, n-propylbenzene, thrimetylbenzenes, octaldehyde, benzaldehyde, 3-vynilpyriridine and naphthalene. According to the EPA, 1999 one of the primary sources of cumene are;
solvent, plastic, cigarette and motor vehicles (Foureman, 1999). Dipentene sources possible in trains could be the cleanning products, fragrances and paints (Falk Filipsson et al., 1998, Park and Ikeda, 2006, Shin and Jo, 2013) (Table V-16).
VOC in restaurant and pubs show high concentrations of compounds such benzene, styrene and benzaldehyde normally found in high concentrations while subjects cook (Huang et al., 2011). Additionally, restaurants also displayed a high concentration of compounds like cumene, pyridine, dipentene, styrene, 3-vinylpyridine and naphthalene. The rest of the compounds appeared only the 90th - percentile.
Compounds sources are associated with traffic and products emissions (Edwards et al., 2001), construction products (Hayashi and Osawa, 2013)
Shops and other microenvironments show differences, and while more compounds were registered in the 90th + percentile for shops than in other indoor environments, most species were found in the 90th - percentile. The outdoor environments show that most of the compounds registered in high concentrations were while subjects spent time in the park compare with the garden. Petrol station concentrations were particularly registered in the 90th - percentile.
147 Table V-16 Correlation between the subject’s activities and the VOC 90th + percentile concentrations.
Locations
Benzene Toluene Ethylbenzene p-xylene m-xylene cumene pyridine o-xylene dipentene n-propylbenzene 1,3,5- Trimethylbenze styrene p- isopropyltoluene 1,2,4- Trimethylbenze Octylaldehyde 1,2,3- Trimethylbenze 2-ethyl -1- hexanol Benzaldehyde 3-vinylpyridine Naphthalene
Home x x x x x x x x x x x x x x x x x x x x
Living room x x x x x x x x x x x x x x x x x x x x
Kitchen x x x x x x x x x x x x x x x x x x x x
Office x x x x x x x x x x x x x x x x x x x
Lab x x x x x x x
Common room x x x x x x x x x x x x x x
Other office x x x x x x x x x x x x x x
Street x x x x x x x x x x x x x x x x x x x x
Car x x x x x x x x x x x x x x x
Car park x x x x
Bus x x x x x x x
Bus stop x x x x
Train x x x x x x x x x x x
Train station x x x x x x x
Restaurant x x x x x x x x x
Pub x x x
Shop x x x x x x x x x x x x x x x x x x
Gym x x x x x x x
Other indoor x x x x
Park x x x x x x x x x x x
Garden x x x x x x
Petrol station
Other outdoor x x x
148 5.5 Conclusion
Under the ambient conditions and the socioeconomic characteristics of the sampling population, it was observed that the higher concentrations were observed in office microenvironments. Most of the sampling volunteers had their offices at the University of Birmingham where work construction was taking place while the sampling campaign was in progress. The influence of outdoor concentration over the indoor and personal exposure was observed. First year concentrations from group two (recently remodelled house) exceed the values obtained for group three (control group) during the same year, mostly for compounds such as: toluene, dipentene, n-propylbenzene, styrene and benzaldehyde. However, the differences were observed for personal and office microenvironment, while increment in concentrations, because houses were new or recently redecorated were not found significantly high compared with old houses.
Possible reason can be observed when group two first sample and second sample were analysed in which the concentrations in a specific house were similar to that obtained from the same house but after a year, except for dipentene which was higher for recently remodelled houses (group two). And by comparing the new a recently remodelled office (Chapter IV) with the FIXAT concentrations, recently redecorated offices were found to have higher concentrations than those observed in new houses for FIXAT cohort. Sampling time might influence the concentration as the FIXAT samples were collected during the first three months of the construction or redecoration, while office samples were collected within a few days after the redecoration.
Based on the 90th percentile analysis, major contributors to the high air pollutant exposure were commuting and street activities such walking and biking. The risk of
149 exposure to air pollutants can be similar considering only the ambient conditions, although the exposure tends to vary based on the location and activity. Therefore, personal exposure measurements are required to accurately establish the relationship between activity and compound concentrations for use in epidemiologic studies.
Everyday activities can be predicted as average concentration, and did not vary significantly between subjects. However, the risk increases with activities that are not performed frequently, or by everyone. Further investigation need to be done considering those microenvironments in which subjects spent less than 30 min. and those that were visited for 1 or 2 subjects as results are only for references and those cannot represent the entire sampled population.
150 CONCENTRATION OF PM2.5, PAHS AND OXY-PAHS
6.1 Introduction
People spend most of the time (60-80 %) in indoor microenvironments, in which a wide range of air pollution sources can be identified (Lim et al., 2012, Harrison et al., 2009).
It is complex to determine the health risks of PM exposure due to the highly variable composition and size of the particles. Therefore, to evaluate the risks it is fundamental to have more information in regards to the composition considering the sources (Hodas et al., 2014). Previous studies have shown poor correlation of PM2.5 between local site and personal exposure with the central sampling site (Anastasopoulos et al., 2012, Hodas et al., 2014, Brokamp et al., 2015), indicating that the level of exposure can be underestimated when it is calculated by using the central site monitors.
PAHs and oxy-PAHs have been reported to be bound to PM, mostly in the PM2.5 size fraction (Anastasopoulos et al., 2012, Choi et al., 2012, Martellini et al., 2012, Cochran et al., 2012, Ringuet et al., 2012, Bandowe et al., 2014), and often show high variability at the local scale (Hänninen et al., 2013, Barrado et al., 2013). These compounds are especially studied because of their carcinogenic/mutagenic proprieties, and within this class of compounds, PAH derivatives have been reported to be more toxic. Higher toxicity in the case of derivatives is attributed to their direct mutagenic potency, since PAH typically require enzymatic activation (1983, Ang et al., 1987, Wei et al., 2012).
6.2 Objectives
To determine the correlation of PM2.5 considering the reported difference between fixed sampling sites with home and personal exposure concentrations, as well as the traditional gravimetric lab method (integrated filter) with online concentrations obtained from the MicroPEMTM
151 To determine the personal exposure to PAHs and oxy- PAHs considering the activities performed by the volunteers.
To assess the possible sources of the compounds based on spatial and temporal variations.
6.3 Methodology