Table 1

Details of component studies included in analyses

Study	10 cities, Russia	Linz, Austria	Scarpol, Switzerland	24 schools, Netherlands	Sidria, Italy
*For the 3 year Austria study: mean NO₂ and range, across areas, of area-level means of three annual measures.
Not all studies measured all pollutants.
NA, not applicable.
Children, n	5559	4155	2783	2065	9393
Main age range	8–12	6–8	6–12	7–12	6–10
Description of study areas
	13 areas in 10 towns of differing size (the largest Ekaterinburg) and industrialisation	Schools assigned to 8 monitors in the city of Linz	10 communities ranging from major cities (Bern, Geneva, Zürich) to small towns	24 schools located within 400 m of freeways, in 19 towns in mid/west Netherlands	46 schools, in 28 areas within 1 km of a monitor in 22 towns, from major cities (eg Rome, Turin) to small towns.
Main questionnaire period
	Apr–May 99	Jan 96–Dec 98	Oct 92–Mar 93	Apr 97–Jul 98	Oct 94–Mar 95
Range of response rates across study areas (%)
	91–100	96–100	37–91	40–86	91–100
Time period of exposure data
	Nov 98–Nov 99	Continuous data from 96–98	1992	April 97–May 98	1 Oct 93–30 Sept 94
Site of monitoring stations
	Background	Background	Background/traffic	Traffic	Background/traffic
Mean NO₂ exposure (min-max) μg/m³
	19.47 (12.45–34.71)	25.91 (20.25–31.25)*	31.60 (16.00–50.00)	34.81 (26.79–44.38)	52.04 (14.00–93.00)
Mean PM₁₀ exposure (min–max) μg/m³
	24.46 (20.47–28.40)	32.14 (25.00–37.43)*	22.30 (10.00–33.00)	34.15 (30.28–38.86)	NA
Mean SO₂ exposure (min–max) μg/m³
	26.27 (6.68–64.93)	7.31 (4.98–10.88)	10.56 (2.00–23.00)	NA	13.00 (2.00–32.00)