Table 1

 Factors relating to pollution exposure in SIDS cases and matched controls (n = 338)

Cases, n (%)Controls, n (%)p
County of residence 0.29
Los Angeles114 (67.5)95 (56.2)
San Bernardino13 (7.7)15 (8.9)
Orange10 (5.9)14 (8.3)
Riverside12 (7.1)15 (8.9)
San Diego19 (11.2)25 (14.8)
Other (Ventura, Kern, Monterey)1 (0.6)5 (3.0)
Distance to pollution monitor (km) 0.62
⩽0.563 (37.3)60 (35.5)
>0.5 to 5.061 (36.1)58 (34.3)
>5.0 to 10.026 (15.4)35 (20.7)
>10.0 to 15.010 (5.9)11 (6.5)
>15.09 (5.3)5 (3.0)
Season of last exposure date 0.85
Winter (December–February)53 (31.4)47 (27.8)
Spring (March–May)58 (34.3)58 (34.3)
Summer (June–August)31 (18.3)32 (18.9)
Autumn (September–November)27 (16.0)32 (18.9)
Last exposure date during a weekend 45 (26.6)44 (26.0)1.00