Prenatal exposure to sand and dust storms and children's cognitive function in China: a quasi-experimental study

BACKGROUND: While there is evidence that sand and dust storms can have adverse health effects, the effects of such storms on children's cognitive function has not been explored. We examined whether prenatal exposure to sand and dust storms affects children's cognitive function and, if so, whether harmful effects of sand and dust storms vary by the trimester of exposure. METHODS: This study used nationally representative data from the China Family Panel Studies between 2010 and 2014 and data on sand and dust storms from the national Sand and Dust Weather Almanac. We selected four indicators of children's cognitive function: mathematics test scores, word-recognition test scores, the age the child began speaking in whole sentences, and the age the child began counting from one to ten. Since the annual incidence of sand and dust storms is highly variable and is largely unpredictable, we used a region-and-year fixed-effect model to compare the cognitive function of children born in the same region and year but with varying amounts of prenatal exposure to sand and dust storms. We also investigated whether the effect of sand and dust storms varied by the specific month of prenatal exposure. FINDINGS: We included 1236 observations for the analysis of mathematics and word-recognition test scores, 2693 observations in the analysis of the age the child began speaking in whole sentences, and 1951 observations for the analysis of the age the child began counting from one to ten. Every 10 additional days of prenatal exposure to sand and dust storms was associated with a 0·20 SD (95% CI 0·06 to 0·35, p=0·009) reduction in word test scores, 0·04 (-0·00 to 0·09, p=0·089) additional months to begin speaking in sentences, and 0·14 (0·03 to 0·25, p=0·021) additional months to begin counting, but was not significantly associated with mathematics test scores (reduction of 0·02 SD, -0·19 to 0·15). 10 additional days of prenatal exposure to sand and dust storms in the seventh gestational month was associated with a 0·18 SD (0·10 to 0·25) reduction in mathematics test scores, a 0·34 SD (0·18 to 0·50) reduction in word test scores, an additional 0·33 months (0·07 to 0·59) to begin speaking in sentences, and an additional 0·20 months (0·04 to 0·35) to begin counting. INTERPRETATION: Our results suggest that protecting pregnant women from the effects of sand and dust storms in the critical periods of fetal brain development could generate benefits for the cognitive function of the next generation.