To examine the effects of prenatal and postnatal exposure to particulate matter on Kawasaki disease (KD) occurrence, using data from a nationwide population-based longitudinal survey in Japan that began in 2010.

Prenatal and postnatal suspended particulate matter concentrations were obtained at municipality level and assigned to participants based on their municipality of birth. We analyzed data from 30 367 participants with data on either exposure period. We used hospital admission for KD from 6 to 30 months of age as the main outcome of interest. We conducted a multilevel logistic regression analysis, adjusting for individual and municipality-level variables.

Children who were exposed to higher levels of suspended particulate matter, in particular during pregnancy, were more likely to be hospitalized for KD. The ORs for ≥25 µg/m³ exposure compared with <20 µg/m³ exposure were 1.59 (95% CI 1.06, 2.38) for prenatal exposure and 1.41 (0.82, 2.41) for postnatal exposure. Prenatal exposure during mid-to-late gestation seemed to be more relevant for the increased risk.

Early life exposure to particulate air pollution, in particular during pregnancy, is associated with an increased risk of KD hospital admission in early childhood in a nationally representative sample in Japan.