Respiratory health, children’s lung function, and air quality in four Chinese cities: two snapshots in 1993–1996 and 2017–2018

摘要

From 1993 to 1996, the original Four Chinese Cities (4CC) study was conducted to examine the effects of outdoor and indoor air pollution on respiratory health symptoms and illnesses and lung function growth in elementary school children. Chongqing, Guangzhou, Lanzhou, and Wuhan were selected, as these cities had distinct pollution sources and provided a large gradient in outdoor levels of particulate matter (PM10, PM2.5) and gaseous pollutants (SO2 and NO2). At the time, characteristic sources were sulfur-rich coal combustion in Chongqing, motor vehicular traffic in Guangzhou, and an oil refinery coupled with coal combustion as well as sand/road dust in Lanzhou, whereas Wuhan did not exhibit a single dominant source as in the other three cities (1,2). The study design included an intra-city comparison by selecting one urban school and one or two suburban schools in each city. Respiratory health conditions were assessed via a questionnaire survey of all the participating children (n=7,557) and their fathers and mothers (3,4). In a randomly selected subset of the children, lung function measurements were made using spirometry approximately every six months on each child from 1993 to 1996. Major findings of the 4CC study include the following: (I) across the four cities, significant positive associations were found between the prevalence of respiratory morbidity in children and outdoor levels of PM of all size fractions, although the association appeared to be stronger for coarse particles (PM2.5-10). Children’s respiratory symptoms were also positively associated with ambient levels of NOx and SO2 (3) and indices of ambient air pollution mixtures (5); (II) household coal use for cooking and heating, environmental tobacco smoke (ETS), and poor kitchen ventilation were each independently associated with increased reporting of respiratory symptoms in children (6); (III) increased exposures to ambient PM2.5 and PM10 were associated with both a lower magnitude and a lower growth rate of children’s lung function (7). (IV) household coal use was significantly associated with reduced lung function growth, whereas the use of household ventilation devices (e.g., fume hoods, fans) was significantly associated with higher lung function growth, particularly among children living in households where coal was used as a cooking and/or heating fuel (8).