Mishra 2014_Volatile Organic Compounds-Characteristics, distribution and...

2                                                   N. Mishra et al. / Atmospheric Environment xxx (2014) 1e7


insufficient ventilation, aggravated by the poor construction and/or                populated city in Australia, with population more than 2 million
maintenance of many school buildings. VOC concentration tends to                   (ABS, 2011). Although the city lies on either side of the Brisbane
be lower in the spacious and well ventilated classrooms with a low                 River, on a low lying flood plain, it is surrounded by hills, some of
occupancy ratio (Pegas et al., 2011b). Accumulation of pollutants is               which reach 300 m in height. The major air pollution sources in
possible when doors and windows remain closed for long periods                     Brisbane include, vehicle emissions, controlled and uncontrolled
of time in order to maintain thermal comfort, especially in winter.                biomass burning in the vicinity of the city and a limited number of
In addition to this, children are involved in different types of art and           industrial activities, such as a power station, oil refineries, the
craft activities, with the use of glue and paints that may increase the            airport, port and a brewery (Morawska et al., 2002). Brisbane has a
level of VOCs in the classroom as reported by Zhang et al. (2006)                  subtropical climate, with a hot and humid summer (mean tem-
and Pegas et al. (2011b). Besides these, the use of cleaning and                   perature 25  C) and a dry, moderately warm winter (mean tem-
other consumer products inside the classroom are also possible                     perature 15  C), with an average diurnal temperature variation
sources of VOCs. If the school is located in an urban environment,                 around 9e10  C.
the air quality can be affected by many other factors, such as the
amount and type of passing traffic, distance from the road and the                  2.2. Study design
location of drop off and pick up areas, together with some meteo-
rological factors, like wind direction and speed.                                  2.2.1. School selection and location
    The pollutants most commonly monitored in elementary school                        The 25 state schools selected for this study, coded as S01 to S25,
studies are carbon dioxide, carbon monoxide, nitrogen dioxide,                     were from a range of different suburbs in the Brisbane Metropolitan
particulate matter (PM10, PM2.5) and inorganic components, as well                 Area. The schools were randomly selected but they need to meet
as biological agents including airborne fungi and bacteria (Meklin                 several selection criteria, which were: (i) no major pollution sour-
et al., 2002; Godoi et al., 2009; Sohn et al., 2009). There have                   ces near the schools other than traffic; (ii) not close to any large
been several studies performed worldwide to assess students'                       infrastructure project, such as a major road, tunnel or building
exposure to indoor particles, but very few aimed at characterizing                 construction; and (iii) naturally ventilated classrooms used by 8e11
their chemical composition, and those that did mainly focused on                   year old children. The general characteristics of each school are
elemental content (e.g. Molnar et al., 2007; Stranger et al., 2008;                described in the Supplementary Table S1.
Almeida et al., 2011; Oeder et al., 2012).
    Due to the long term health risks associated with organic pol-                 2.2.2. Sampling period and sites
lutants, there is increased concern about their presence in the air of                 The field measurements were conducted throughout the year,
schools. A study conducted by (Godwin and Batterman, 2007) in 64                   from October 2010 until August 2012, except on school holidays.
classrooms in Michigan, USA reported that benzene, ethylbenzene,                   There were two sampling sites for VOCs at each school - one out-
toluene, xylene and limonere were the prevalent VOCs. Sofuoglu                     door and one indoor. The outdoor site was chosen in a central
et al. (2011) measured the concentrations of VOCs in classrooms,                   location within the school grounds, which was assumed to repre-
kindergartens and outdoor playgrounds of three primary schools in                  sent the air quality within the school as best as possible. The indoor
Turkey in different seasons and found the concentrations were                      site was a classroom used by 8e11 year old children. All of the
higher indoors than outdoors. Ten VOCs were identified in the study                 classrooms were naturally ventilated via doors and windows, with
conducted in three primary schools in Western Australia (Zhang                     an occasional use of a fan or local air conditioning systems, which
et al., 2006), of which the highest concentration was measured in                  were not operated during the measurements. Doors and windows
the visual art classroom. Pegas et al., 2011a, Pegas et al., 2012                  were usually closed while doing indoor measurements. Children
investigated the pollutant (organic and inorganic) concentrations                  were involved in different activities inside the classroom, including
inside and outside school buildings and found the important                        painting, art and craft.
contribution from indoor sources. In general, literature reports
higher VOC concentrations indoors than outdoors. None of the above                 2.3. Sample collection and analytical methods
studies investigated on the sources of VOCs and their contributions.
Therefore, the identification and of outdoor and indoor sources of                     VOCs samples were collected using active sampling procedure
VOCs particularly in school environment is still lacking.                          by a portable VOC pump. The flow rate was set to 150 mL/min. The
    To address this gap in knowledge, the following aims were                      measurements were taken at the height of 1.5 m from the ground.
established for this study: 1) to conduct comprehensive measure-                   Stainless steel desorption tubes filled with Tenax TA ((20/35 and
ments of VOCs in indoor and outdoor air of representative number of                60/80 mesh; 300 mg) were used indoors to prevent terpenes and
urban primary schools; 2) to quantify the relationship between in-                 aldehydes from analytical losses. To avoid artefacts (due to reactive
door and outdoor VOCs concentrations; 3) to identify the VOCs                      gases like ozone or NOx) tubes were filled with carbotrap (20/40
sources and activities contributing to these sources in urban schools              mesh; 300 mg) for outdoor measurements. Air samples were
and 4) to identify the optimal scenarios for reduction of VOCs                     collected between 7 am and 5 pm, each day (outdoor: 9:00 am,
exposure to children at schools. This study is a part of larger project            9:45am, 1:10 pm, 1:55 pm; indoor: 7:00 am, 7:45 am, 3:00 pm, 3:45
called “The Effect of Ultrafine Particles from Traffic Emissions on                  pm; volume: 6 L) in each school. Several sampling periods,
Children's Health (UPTECH),” which seeks to determine the effect of                including before the start of class, during school and after school
exposure to traffic generated ultrafine particles and organic pollut-                hours was chosen. There were no students and teachers inside the
ants in schools. The complete study design is available online (http://            classroom during the indoor measurements. Once the sampling
www.ilaqh.qut.edu.au/Misc/UPTECH%20Home.htm).                                      was completed, the tubes were made air tight using screw caps,
                                                                                   placed in a ziplock plastic bag and sent to Fraunhofer WKI,
2. Experimental section/material and methods                                       Braunschweig, Germany for analysis.
                                                                                      Laboratory analysis of all sorbent tubes was performed via
2.1. Study location                                                                thermal desorption/gas chromatography, coupled with mass
                                                                                   spectrometry (TD-GC/MS), according to DIN ISO 16000-6. An Agi-
   Brisbane, the capital city of the State of Queensland, is located               lent 7890/5975 GC/MS system equipped with a Markes TD 100
along the South-East coast of the state and is the third most                      thermal desorber was used and the compounds were separated on


    Please cite this article in press as: Mishra, N., et al., Volatile Organic Compounds: Characteristics, distribution and sources in urban schools,
    Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.10.052