Abstract
To assess the contribution of carcinogenic Polycyclic Aromatic Hydrocarbons (PAHs) in ambient air, EU Directive 2004/107/EC indicates to monitor relevant carcinogenic PAHs in PM10 fraction other than benzo(a)pyrene at a limited number of measurement sites. This indication refers to outdoor environments, and the environmental air quality being taken as a reference also for indoors, it can be extended to indoor environments. In this work, the contribution of carcinogenic PAHs bound to PM10 has been evaluated in winter in two classrooms of a University campus in Rome with the aim of studying the relationship with the outdoors and with working activity. PM10-boundPAHs were monitored over five different periods selected to distinguish Weekend from daytime and nighttime Weekdays, separated into two parts of the week. Data aggregated over Weekend and Weekdays allowed calculating of the concentration of carcinogenic PAHs, the mass contribution to PM10, the Infiltration Factor, the indoor to outdoor Ratio, and the Total Carcinogenic Potency by Toxicity Equivalent Factors, for “not-working” and “working” days. In addition, some indications on contributions to the source have been obtained from the chemical profile normalized to the maximum value of concentration, which also provides the source fingerprint compound. Indoor PAH concentrations were lower than outdoor, and both accumulated as the week progressed. Although the two indoor environments were on the same floor and had a similar volume, they presented different contribution to PM10 and infiltration capacity, both higher during Weekend than on Weekdays. The analysis of indoor and outdoor chemical profiles normalized to the maximum concentration indicated an external source infiltrating the indoors environment. During Weekdays, the indoor fingerprint compound changed compared to that observed during Weekend, probably due to an additional contribution of local “fresh-traffic” source. The calculation of Total Carcinogenic Potency gave indoor values always lower than outdoor, confirming in the two classrooms different dynamics for carcinogenic PAHs. Moreover, the Total Carcinogenic Potency on Weekdays was twice that of Weekend, meaning a higher toxicological impact when urban “fresh-traffic” source is added. The present study shows that the dynamics of PM10-related carcinogenic PAHs can be different within adjacent classrooms of a building and during working and not-working days. This evidence suggests the possibility of a potential different impact on occupant exposure to be taken into account in planning monitoring programs of indoor pollution.
Highlights
Polycyclic Aromatic Hydrocarbons (PAHs) are products of incomplete combustion of different organic materials that can be found in the air both as gases and bound to PM, and can be natural or artificial [1].Main anthropogenic sources of PAHs include residential heating and motor vehicle exhaust, as well as industrial activity [2]
The total mean of cPAH concentrations indoors ranged from 1.96 ng/m3 (A4, P2) to 10.4 ng/m3 (CR, P3); outdoors, from 4.29 (P2) ng/m3 to 16.9 (P5) ng/m3, the latter being the highest value averaged over the six sampling weeks
The lowest mean concentrations of congeners were measured for DahA, BaA and CH, which together contributed to about 10% of the total mass of cPAHs
Summary
Main anthropogenic sources of PAHs include residential heating and motor vehicle exhaust, as well as industrial activity Sustainability 2021, 13, 10790 black, coal-tar pitch and asphalt production, coke and aluminum production, catalytic cracking towers and activities in petroleum refineries) [2]. The distribution between air and particulate phases depends on chemical-physical properties of PAHs, e.g., adsorption of soot carbon, the major mechanism governing gas/particle partitioning [3]. Occupational exposure to PAHs causes diverse effects either for short-term exposure or for long-term, as well as residential exposure, even if in the latter case the evidence for a short-term effect is more weak than that for long-term [7,8]. Carcinogenicity is the most harmful characteristic for human health and there is evidence that prenatal exposure to carcinogenic PAHs is associated with intrauterine growth restriction in humans [12,13]
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