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Sampling site

FIGURE 10.18 Seasonal variation in the mutagen density (rev m~3, TA98, — S9) of extracts of ambient particles, and the associated BaP levels (ng m~3), collected at four sites in Athens, Greece, February 1984-January 1985. The annual average was 1.9 rev m-3 (adapted from Viras et al., 1990).

Sampling site

FIGURE 10.18 Seasonal variation in the mutagen density (rev m~3, TA98, — S9) of extracts of ambient particles, and the associated BaP levels (ng m~3), collected at four sites in Athens, Greece, February 1984-January 1985. The annual average was 1.9 rev m-3 (adapted from Viras et al., 1990).

m~3, TA98 — S9) and the concurrent BaP levels of ambient aerosol samples taken at four sites in Athens once or twice weekly over a period of one year (February f984 to January 1985). The mean annual values of mutagenicity (1.5-2.5 rev m~3) are low relative to other polluted urban areas.

Figure 10.19 shows results from a similar study conducted in Padova, Italy, by Nardini and Clonfero (1992). Sampling (TA98, +S9/-S9) was at street level for 3-h periods in the morning for 23 summer and 22 winter events between June 1990 and February 1991; stations were at eight streets with different widths and traffic volumes. Mean values on TA98NR for all samples ( + S9 and — S9) were lower in both the summer (by ~38%) and the winter (by ~49%), indicating the presence of nitroarenes (see Section C.2). Similar examples of higher mutagenicities in winter have been reported by others (e.g., Tuominen et al., f988; De Flora et al., 1989; Flessel et al., 1991; Bodzek et al., 1993; Scarpato et al., 1993; Nielsen et al., 1999a, 1999b; Matsumoto et al., 1998). Note, however, that winter averages are not always higher than summer averages. For example, Bayona and co-workers (1994) found the

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