Table 2.

Distribution of PM₁₀ and NO₂ exposure levels for different pregnancy periods.

Air pollution level	Minimum	25th percentile	Mean	Median	75th percentile	Maximum
PM10 exposure (μg/m3)
Until first trimester		21.7		27.4		30.8		30.8		33.6		44.0
Until second trimester		22.6		28.0		30.7		30.6		33.6		43.2
Until third trimester		22.7		27.8		30.4		30.5		33.2		41.5
Total pregnancy		23.2		27.8		30.3		30.0		32.9		40.9
NO2 exposure (μg/m3)
Until first trimester		21.0		37.0		40.4		40.9		43.9		59.7
Until second trimester		22.7		37.0		40.2		40.5		43.4		58.4
Until third trimester		25.6		37.0		40.0		39.8		42.8		58.2
Total pregnancy		26.5		37.2		39.8		39.6		42.2		56.9
Air pollution exposure was estimated for different periods in pregnancy: conception until first, second, and early third trimester ultrasound, and conception until delivery.