2.3 Exposure assessment of the air pollutants
The ambient air pollutant data were obtained from dynamic monitoring
data of air pollutants collected at 17 ambient air quality monitoring
stations in Jinan. Daily 24-hour average concentrations of
SO2, NO2, CO, PM10,
PM2.5, and daily maximum 8-hour average concentrations
of O3 were obtained for the birth cohort population
between the date of the last menstrual period of the earliest pregnant
mother and the date of birth of the latest child who had reached the age
of 2 years. Then obtained the PM2.5-10 concentration by
subtracting the PM2.5 concentration from the
PM10 concentration. The residence address of the mother
during pregnancy and after the birth of the child, the date of the
mother’s last menstrual period for the current pregnancy and the date of
birth of the child were collected through questionnaires at the baseline
and follow-up surveys of the cohort study, and the pollutant
concentrations measured at 17 monitoring stations were weighted
according to the spatial distance between the home address and the
concentration at the monitoring station using the Inverse Distance
Weighting (IDW) model to obtain the individual pollutant concentrations
for each study subject(Rishikeshan, Katiyar, Mahesh, & Ieee, 2014).
2.4 Covariate
Child information Gender, birth weight, breastfeeding, birth
mode, use of masks, and preterm birth.
Parental information Parental atopy, maternal age at delivery,
work during pregnancy, maternal primipara.
Family information House decoration, home dampness, use of
carpet, pets, monthly household income, open windows often, air purifier
use.
Parental atopy was defined as either parent having had an allergic
disease, including eczema, allergic rhinitis, food and drug allergy, or
asthma. Working during pregnancy was defined as the act of the mother
continuing to work in the workplace during pregnancy. Home dampness was
defined as having at least one of the following dampness-related
exposures in the dwelling environment: visible mold stains, visible damp
stains, damp clothing/bedding, condensation on windows, or moldy odors.
Open windows often was defined as three or more window openings in a
week by the child’s cohabitants.