Table 1

Means and SD of daily counts of hospital admissions for autism spectrum disorder, air pollution levels and meteorological factors during the study period (2011–2015)

TotalWarm seasons*Cool seasons†
Daily counts of hospital admissions
Autism spectrum disorder
Total8.5 (8.2)8.3 (7.9)8.8 (8.4)
Boys7.0 (6.9)6.8 (6.8)7.1 (7.0)
Girls1.6 (1.5)1.5 (1.4)1.7 (1.7)
Air pollution levels‡
PM2.5 (µg/m3)19.3 (14.7)15.1 (11.1)23.6 (16.6)
NO2 (ppb)20.7 (10.7)17.6 (9.1)23.8 (11.3)
O3 (ppb)37.2 (16.4)43.0 (16.6)31.4 (13.9)
Meteorological factors
Temperature (℃)13.2 (9.8)21.3 (4.5)5.0 (6.3)
Relative humidity (%)67.0 (15.2)72.7 (12.5)61.3 (15.4)
  • Values are presented as mean (SD).

  • *May–October.

  • †November–April.

  • ‡Daily mean concentrations of PM2.5 and NO2 and daily 8 hours maximum concentrations of O3.

  • NO2, nitrogen dioxide; O3, ozone; PM2.5, particulate matter.