The joint effect of cumulative doses for outdoor air pollutants exposure in early life on asthma and wheezing among young children.

BACKGROUND: Constrained by no proper way to assess cumulative exposure, the joint effect of air pollution cumulative exposure doses on childhood asthma and wheezing (AW) was not understood. OBJECTIVE: To assess the association between cumulative exposure to multiple air pollutants in early life and childhood AW. METHODS: We designed a nested case-control study based on the birth cohort in Jinan City. Children with AW followed up within 2 years after birth were treated as cases, and non-cases in this cohort were treated as the control source population, and the propensity score matching method was used to match each case to 5 controls. We calculated the individual cumulative outdoor exposure doses for each period using an inverse distance weighted model, alongside the complex Simpson's formula, accounting for outdoor time and respiratory volume. The Least absolute shrinkage and selection operator (Lasso) regression was performed to screen for covariates. To analyze the joint effects of pollutants, we employed the weighted quantile sum (WQS) regression model in conjunction with conditional logistic regression. RESULTS: 84 cases and 420 controls were included in this study. The odds ratio (OR) with 95% confidence interval (CI) of the impact of cumulative exposure (mg/m3) after birth on childhood AW was 1.78 (1.15-2.74) for SO2, 1.69 (1.11-2.57) for NO2, and 1.65 (1.09-2.52) for PM2.5, respectively. Furthermore, with each 25th percentile increase in the WQS index, the overall risk of cumulative doses for six pollutants exposure after birth on AW increased by an adjusted OR of 1.10 (1.03, 1.18), and SO2, PM2.5, and NO2 contributed the most to the WQS index. However, no statistically significant association was found between cumulative exposure to all pollutants before birth and childhood AW. CONCLUSIONS: There was a joint effect of the cumulative exposure dose of outdoor air pollutants after birth on AW in children aged 0-2 years. And traffic-related pollutants (SO2, PM2.5, and NO2) make a greater contribution to the joint effect.

The Association Between Exercise During Pregnancy and the Risk of Preterm Birth.

Purpose: We aimed to examine the association between exercise during pregnancy and preterm birth (PTB). Methods: This study was a baseline survey of the Jinan birth cohort. The study subjects were the mothers one month after giving birth, which were investigated by questionnaires retrospectively containing physical exercise (frequency, time, and primary exercise patterns) during pregnancy and each trimester. Individual time spent on exercise and energy expenditure were assessed based on the questionnaires. PTB was clinically defined as a newborn born on or before the last day of the 37th week. Adjusted odds ratios (OR) were estimated using logistic regression to assess the relationship between exercise during pregnancy and the risk of PTB. Variable selection for the multivariate models was guided by the directed acyclic graph. The median effect was analyzed by the sequential test. Results: The prevalence of PTB in this study was 4.38% (285/6501). The adjusted OR (95% CI) for the risk of PTB related to exercise during pregnancy was 0.74 (0.58-0.95). During the 1st and 2nd trimesters, the ORs (95% CI) for 2.5 to 7 hours of exercise per week were 0.77 (0.59-0.99) and 0.74 (0.57-0.96). During the 3rd trimester, the ORs (95% CI) for 2.5 to 7 hours and more than 7 hours of exercise per week were 0.74 (0.56-0.96) and 0.65 (0.44-0.94). After stratifying the subjects, the association was only found among subjects without pregnancy complications. Pregnancy complications partially mediated (52.40%) the relationship between exercise during pregnancy and PTB. Conclusion: Exercise during pregnancy can reduce the risk of PTB for women without pregnancy complications. 2.5 to 7 hours of exercise (like walking) per week may be appropriate in three trimesters of pregnancy, and the time could be extended in the 3rd trimester.

Short-term and long-term effects of cesarean section on asthma and wheezing: A cohort study and meta-analysis.

OBJECTIVE: To describe the short-term and long-term effects of cesarean section on childhood asthma and wheezing. METHOD: Firstly, in the cohort study, 6640 infants were included in the cohort baseline from January 2018 to December 2019, in which 6501 children completed the follow-up study for respiratory diseases at age 2 years. The effect of cesarean section on asthma and wheezing was estimated by the logistic regression model. Secondly, we conducted a meta-analysis of studies with outcomes of childhood asthma and wheezing under 2 years of age and over 2 years of age, respectively, to investigate the short-term and long-term effects of cesarean section on asthma and wheezing. RESULTS: In our cohort study, the cumulative incidence of asthma and wheezing was 1.3% (84/6501). 45.5% of children (2961/6501) were born by cesarean section. The adjusted odds ratio for the effect of cesarean section on asthma and wheezing in children under 2 years of age was 1.14 (95%CI 0.73-1.78). Combining previous studies (outcomes of asthma and wheezing under 2 years of age) with our results for a meta-analysis, the odds ratio was 1.15 (95%CI 1.05-1.25, I2 = 46.82%). Meanwhile, cesarean section had a long-term effect on asthma and wheezing in the child population over 2 years of age (OR = 1.17, 95%CI 1.11-1.24, P < 0.001, I2 = 79.38%). CONCLUSION: Cesarean section had a short-term effect on asthma and wheezing before the age of 2, in addition, the long-term effect of cesarean section on asthma and wheezing persisted in the child population (under 18).

Maternal apparent temperature during pregnancy on the risk of offspring asthma and wheezing: effect, critical window, and modifiers.

The objective of this study was to explore the impact of maternal AT during pregnancy on childhood asthma and wheezing, as well as the potential effect modifiers in this association. A cross-sectional study was implemented from December 2018 to March 2019 in Jinan to investigate the prevalence of childhood asthma and wheezing among aged 18 months to 3 years. Then, we conducted a case-control study based on population to explore the association between prenatal different AT exposure levels and childhood asthma and wheezing. The association was assessed by generalized additive models and logistic regression models, and stratified analyses were performed to explore potential effect modifiers. A total of 12,384 vaccinated children participated in screening for asthma and wheezing, 236 cases were screened, as well as 1445 controls were randomized. After adjusting for the covariates, childhood asthma and wheezing were significantly associated with cold exposure in the first trimester, with OR 1.731 (95% CI: 1.117-2.628), and cold exposure and heat exposure in the third trimester, with ORs 1.610 (95% CI: 1.030-2.473) and 2.039 (95% CI: 1.343-3.048). In the third trimester, enhanced impacts were found among girls, children whose distance of residence was close to the nearest main traffic road, and children whose parents have asthma. The study indicates that exposure to extreme AT during the first and third trimesters could increase the risk of childhood asthma and wheezing.

A life course approach to asthma and wheezing among young children caused by ozone: A prospective birth cohort in northern China.

BACKGROUND: Given differences in vulnerability of children in early life, a life course approach to asthma and wheezing (AW) in young children caused by ozone (O3) is not fully understood. METHODS: We conducted a birth cohort in Jinan, China from 2018 to 2021 to elucidate the onset model of childhood AW due to O3 exposure. An inverse distance weighted model was used for individual exposure assessment. The time-dependent Cox proportional-hazard model and logistic model were used to investigate the effects of O3 exposure on AW. Principal component analysis, interaction analysis, and distributed lag model were used to analyze the life course approach. RESULTS: The cumulative incidence rate for AW among 6501 children aged 2 was 1.4%. A high level of O3 was related to AW (HR: 2.10, 95% CI: 1.31, 3.37). Only O3 exposure after birth was associated with AW, with an OR of 1.82 (1.08, 3.12), after adjusting for the effect before birth. Furthermore, adjusting for other air pollutants, the HR for the individual effect of high O3 exposure on AW was 2.44 (1.53, 3.89). Interestingly, P values for interactions for O3 and the principal components of other pollutants, as well as the characteristic variable of open windows were less than 0.1. Moreover, an increase in the IQR of O3 exposure at the 31st to 37th weeks before birth and the 1st to 105th weeks after birth was associated with an increase in the HRs for AW. CONCLUSIONS: High-level of O3 exposure after birth could lead to AW among young children. Importantly, the AW onset model may include the risk factors accumulation and the sensitive period model. Specifically, there are two sensitive windows in early life, and the correlated insults between the high level of O3 and other pollutants as well as open windows in the asthma-inducing effect.

The causal and independent effect of ozone exposure during pregnancy on the risk of preterm birth: Evidence from northern China.

The concentration of ozone (O3) in the environment is gradually increasing, but there are limited reports on the exposure to O3 during pregnancy on the risk of adverse birth outcomes. Our study aimed to examine the causal and independent effect of O3 exposure during pregnancy on the risk of preterm birth (PTB) and to identify the critical window. Based on the baseline population of the birth cohort in Jinan, northern China, we obtained the individual exposure for each subject during pregnancy of ambient 8-h moving average O3 through the inverse distance weighting model. The effect of O3 exposure during pregnancy on PTB was evaluated through the time-dependent Cox proportional-hazard models. And we assessed the causal relationship by controlling unknown confounding factors using the instrumental variable (IV) analysis, estimated the independent effect by principal component analysis, and identified the critical window period of exposure through the distributed lag model. Among 6501 subjects, 285 mothers delivered prematurely. The median (IQR) of O3 concentration during pregnancy was 109.51 (23.54) µg/m3. The high level of O3 exposure (>173.64 µg/m³) increased the risk of PTB, with HR of 1.92 (95% CI: 1.38-2.66). Furthermore, the HR (95% CI) of the O3 estimated value calculated by the IV (wind speed) on the risk of PTB was 2.63 (1.41-4.88). In addition, the high level of O3 exposure was associated with the risk of PTB in the 13th-18th gestational weeks. Therefore, the high level of O3 exposure during pregnancy may independently increase the risk of PTB, which may be a causal effect. The 13th to 18th week of gestation is a critical window for preventing this risk.

The effect and its critical window for ambient temperature and humidity in pregnancy on term low birth weight.

As common meteorological factors in daily life, there is limited evidence for the effect of ambient temperature and humidity during pregnancy on the risk of term low birth weight. Furthermore, little is known about the interaction of ambient temperature and humidity on TLBW. The objective of the study was to explore the effect of ambient temperature, humidity during pregnancy, and their interaction on the risk of TLBW and, moreover, to identify exposure critical window. We recruited 6640 infants and their mothers to build a birth cohort study in Jinan City, China, from January 2018 to December 2019. The associations between temperature and humidity during pregnancy and TLBW were estimated by generalized additive model, logistic regression model, and interaction analysis, and the critical window was identified by the distributed lag non-linear model. The incidence of TLBW was 1.36% for the infants in the birth cohort. TLBW was related to the low level of temperature and humidity in the whole pregnancy, compared with the moderate level and the adjusted ORs were 4.44 (1.65-11.42) and 6.23 (1.92-21.39), respectively. The indicators of the interaction analysis of temperature and humidity were not statistically significant. For the low level of humidity, the association with TLBW was statistically significant at first to sixth gestational weeks, and the maximum OR in male infants (3.95, 1.70-9.16) was higher than that in females (1.96, 1.06-3.63). For the low level of temperature, we failed to find significant association with TLBW at each gestational week. The low level of temperature and humidity during pregnancy could increase the risk of TLBW. There was no statistical interaction between temperature and humidity on TLBW. Moreover, the early stage of pregnancy was the critical window for humidity exposure, in which the boys had a greater effect.

The effect window for sulfur dioxide exposure in pregnancy on childhood asthma and wheezing: A case-control study.

BACKGROUND: The relationship between prenatal exposure to sulfur dioxide (SO2) and childhood wheezing and asthma is unclear. OBJECTIVE: To explore the association between prenatal exposure to SO2 and childhood wheeze and asthma. To investigate the effects for the exposure during different pregnancy trimesters. METHODS: We conducted a cross-sectional study firstly in Jinan City to get the prevalence of wheeze and asthma on children aged 18 months to 3 years. And then, we designed a case-control study based on population to evaluate the association between prenatal SO2 exposure and childhood asthma and wheezing. Based on the starting and ending date of pregnancy and specific residential addresses, the individual concentrations of SO2 during pregnancy was evaluated using an inverse distance weighted model. RESULTS: The prevalence of wheeze and asthma on children aged 18 months to 3 years was 2.07% in our cross-sectional study. 236 cases and 1445 controls were available for exposure estimates. The OR (95% CI) of 1.296 (1.130-1.491) was significant after adjusting for the covariates. In the first and third trimesters, the effects were enhanced to 1.602 (1.275-2.022) and 1.448 (1.179-1.783) in the multi-pollutant model with adjusting the effects of other trimesters. Coincidentally, the SO2 exposure level of the case in the first trimester was higher than that in the second and third trimesters (P < 0.001); however, there was no significant difference in exposure levels of the case between the second and third trimesters of pregnancy (P = 0.381). CONCLUSION: Prenatal exposure to higher concentration of SO2 could increase the risk of asthma and wheezing in younger children. The first trimester might be just the window for the toxic effect, while the third trimester was the sensitive window for the effect of SO2 exposure during pregnancy on childhood asthma.

The Characteristics of Air Pollutants during Two Distinct Episodes of Fireworks Burning in a Valley City of North China.

BACKGROUND: The elevation and dissipation of pollutants after the ignition of fireworks in different functional areas of a valley city were investigated. METHODS: The Air Quality Index (AQI) as well as inter-day and intra-day concentrations of various air pollutants (PM10, PM2.5, SO2, NO2, CO, O3) were measured during two episodes that took place during Chinese New Year festivities. RESULTS: For the special terrain of Jinan, the mean concentrations of pollutants increased sharply within 2-4 h of the firework displays, and concentrations were 4-6 times higher than the usual levels. It took 2-3 d for the pollutants to dissipate to background levels. Compared to Preliminary Eve (more fireworks are ignited on New Year's Eve, but the amounts of other human activities are also lesser), the primary pollutants PM2.5, PM10, and CO reached higher concentrations on New Year's Eve, and the highest concentrations of these pollutants were detected in living quarters. All areas suffered from serious pollution problems on New Year's Eve (rural = urban for PM10, but rural > urban for PM2.5). However, SO2 and NO2 levels were 20%-60% lower in living quarters and industrial areas compared to the levels in these same areas on Preliminary Eve. In contrast to the other pollutants, O3 concentrations fell instead of rising with the firework displays. CONCLUSION: Interactions between firework displays and other human activities caused different change trends of pollutants. PM2.5 and PM10 were the main pollutants, and the rural living quarter had some of the highest pollution levels.