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6 jour nal o f e nvironmental sciences 93 (2020) 1 e12

Fig. 3 e Top 10 species contributing to SOAP on (a) winter normal days, (b) winter polluted days, (c) summer normal days,
and (d) summer polluted days.

acetaldehyde. In contrast, in summer, acetaldehyde made the
largest contribution, 22.00% and 21.61% on the normal and
polluted days, respectively, followed by n-hexanal. These re-
sults infer the importance of more rigorously controlling the
emission of alkenes, such as ethylene, during winter, and
OVOCs, such as acetaldehyde, during summer to address the
ozone pollution problem in Beijing.

2.5. Health risk assessment

Haze in Beijing constitutes a large concentration of VOCs,
and some of these species may pose a threat to the health
of the public. Probability and deterministic were used to es-
timate the risk of inhalation of VOCs to humans, and the
risk of inhalation was divided into carcinogenic and non-
carcinogenic (Choi et al., 2011). USEPA (2009) developed an
Fig. 4 e Variation in the contribution of VOC components to
inhalation dosimetry methodology to estimate human health
OFP.
risks associated with the inhalation of VOCs. The hazard ratio
(HR) and the lifetime cancer risk (LCR) were calculated to es-
Fig. 5 shows the top 10 OFP species across the seasonal timate the non-carcinogenic and carcinogenic health risks
using Equations (4)e(6) (Tohid et al., 2019).
days studied. Among the top 10 species, alkenes, aromatics,
and OVOCs contributed the most to the OFP, regardless of the EC
seasons days studied. The OFP values of the top 10 species HR ¼ RfC 1000 (4)
were higher during the polluted days than during the normal
days. In winter, ethylene contributed the most to the total CA ET EF
EC ¼ (5)
OFP, accounting for 26.00% on the normal days and 27.64% on 365ðdays=yearÞ 24ðhours=dayÞ
the polluted days, followed by propylene, m/p-xylene, and