Resumo (PT):
Abstract (EN):
Urban air quality and real human exposure to chemical environmental stressors is an issue of high scientific and
political interest. In an effort to find innovative and inexpensive means for air quality monitoring, the ability of
car engine air filters (CAFs) to act as efficient samplers collecting street level air, to which people are exposed to,
was tested. In particular, in the case of taxis, air filters are replaced after regular distances, the itineraries are almost
exclusively urban, cruising mode is similar and, thus, knowledge of the air flow can provide with an integrated city
air sample. The present pilot study focused on polycyclic aromatic hydrocarbons (PAHs), the most important category of organic pollutants associated with traffic emissions. Concentrations of ΣPAHs in CAFs ranged between 650
and 2900 μg CAF−1
, with benzo[b]fluoranthene, benzo[k]fluoranthene and indeno[123-cd]pyrene being the most
abundant PAHs. Benzo[a]pyrene (BaP) ranged between 110 and 250 μg CAF−1
, accounting regularly for 5–15% of
the total carcinogenic PAHs. The CAF PAH loads were used to derive road-level atmospheric PAH concentrations
from a standard formula relating to the CAF air flow. Important parameters/assumptions for these estimates are
the cruising speed and the exposure duration of each CAF. Based on information obtained from the garage experts,
an average ‘sampled air volume’ of 48,750 m3 per CAF was estimated, with uncertainty in this calculation estimated to be about a factor of 4 between the two extreme scenarios. Based on this air volume, ΣPAHs ranged between
13 and 56 ng m−3 and BaP between 2.1 and 5.0 ng m−3
, suggesting that in-traffic BaP concentrations can be
many times higher than the limit values set by the UK (0.25 ng m−3
) and the European Union (1.0 ng m−3), or
from active sampling stations normally cited on building roof tops or far from city centres.
Notwithstanding the limitations of this approach, the very low cost, the continuous availability of very high
amounts of “sample”, and the “retroactivity” render it very useful and complementary to existing passive sampling techniques. This approach yields estimated air concentrations that reflect the pollutant concentrations to
which taxi drivers, pedestrians, cyclists and road-related professionals are exposed
Language:
English
Type (Professor's evaluation):
Scientific
No. of pages:
6