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

Synergistic Toxicity of Fine Particulate Matter and Ozone and Their Underlying Mechanisms

The co-occurrence of fine particulate matter (PM2.5) and ozone has emerged as a critical environmental challenge in recent years. The individual harmful impacts of PM2.5 and ozone exposure have been well studied; however, their combined toxicity under co-exposure conditions remains mechanistically undefined. This paper provides an extensive evaluation of the current pollution levels, epidemiological investigation, and new findings on the toxicological mechanisms of combined exposure to PM2.5 and ozone. The synergistic toxicity of PM2.5 and ozone depends on different factors, including the physicochemical properties of PM2.5, the dose and duration of exposure, and the specific target organs. Through extensive research, we identified the main targets of toxic responses to PM2.5 and ozone exposure and summarized their synergistic toxic mechanisms. Given the current research priorities, there is an urgent need to improve scientific research regarding PM2.5 and ozone co-exposure with priority given to characterizing their properties and toxicological responses while updating relevant guidelines and standards.

The value of ultrasound spectra of middle cerebral artery and umbilical artery blood flow in adverse pregnancy outcomes

OBJECTIVES

To evaluate the diagnostic value of ultrasound spectra of the middle cerebral artery (MCA) and umbilical artery (UA) blood flow in predicting adverse pregnancy outcomes.

METHODS

Data from 202 late singleton pregnancies (32-34 weeks gestation) were analyzed. Group A included 155 normal pregnancies, while Group B comprised 47 high-risk pregnancies. Color Doppler ultrasonography was used to measure and compare pulsatility index (PI), resistance index (RI), and end-systolic peak/end-diastolic peak (S/D) ratios of fetal MCA and UA between the groups.

RESULTS

UA-related parameters (PI, RI, and S/D) were significantly higher in Group B compared to Group A, whereas MCA-related parameters (PI, RI, and S/D) were significantly lower in Group B than in Group A. In pregnancies with adverse outcomes, fetal UtA and UA-related parameters were elevated, while MCA parameters were decreased compared to those with favorable outcomes.

CONCLUSIONS

Ultrasound spectra of MCA and UA blood flow provide valuable clinical information for assessing fetal intrauterine growth and predicting adverse pregnancy outcomes.

Early-life ozone exposure and childhood otitis media: Unveiling critical windows of risk

BACKGROUND

Despite increasing evidence of a strong correlation between air pollution and otitis media (OM), the impact of early-life ozone (O3) exposure on the development of OM in children remains uncertain.

OBJECTIVES

To explore the connection between early-life O3 exposure and OM, and to identify the critical time period(s) during which O3 exposure significantly influences the development of OM in children.

METHODS

We conducted a study involving 8689 children living in Changsha, China. Information regarding personal factors, health conditions, and the indoor environment was gathered using questionnaires. Personal exposure to outdoor O3 and other major pollutants at the place of residence during the periods before conception, prenatal periods, and after birth was calculated by applying the inverse distance weighted (IDW) method with data gathered from ten air quality monitoring stations. Multiple logistic regression analyses were employed to investigate the associations between O3 exposure and children's OM.

RESULTS

After controlling for covariates and ambient temperature, exposure to O3 during the year preceding pregnancy was correlated with childhood lifetime OM, showing ORs (95 % CI) of 1.28 (1.01-1.64). O3 exposures in the 10th-12th, 7th-9th, and 4th-6th months before pregnancy were all linked to children's lifetime OM. Within the multi-window model, we detected that O3 exposure in the 10th to 12th month prior to pregnancy was significantly related to lifetime OM, showing ORs (95 % CI) of 1.28 (1.05-1.55). A significant link was discovered between childhood OM and O3 exposure after controlling for six other pollutants (SO2, PM2.5, NO2, PM2.5-10, CO, and PM10) during the 10th to 12th month prior to conception. Exposure to O3 during the 36th gestational week significantly raised the likelihood of childhood lifetime OM. There is a significant interaction between O3 and temperature exposure during the first trimester of pregnancy and one year before pregnancy on childhood lifetime OM.

CONCLUSIONS

Preconceptional O3 exposure and its interaction with low temperature played critical roles in children's OM development, backing the hypothesis of "(pre) fetal origins of childhood OM".

Prenatal air pollutant exposure and preterm birth risk in primiparas of advanced maternal age residing in rural Henan province

Direct evidence on the impact of air pollution on preterm birth (PTB) among advanced maternal age (AMA) primiparas is limited. This study examined the association between air pollution and PTB among 6,295 AMA primiparas in rural Henan Province. Logistic regression and distributed lag nonlinear models showed that prenatal exposure to carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), and fine particulate matter (PM2.5) was associated with an increased PTB risk among AMA primiparas, while ozone (O3) exposure was inversely related to PTB risk (all P < 0.05). Moreover, the vulnerable periods were identified as gestational weeks 1-6 and 22-28. The education level, smoking status, and season of conception significantly modified the association between PTB and air pollution (P interaction < 0.10) among AMA primiparas. These findings emphasize the impact of air pollution on PTB risk in AMA primiparas, highlighting the need for targeted interventions in vulnerable populations.

Long-term exposure to ambient ozone and adult-onset asthma: A prospective cohort study

BACKGROUND

The association between long-term exposure to ozone (O3) and adult-onset asthma (AOA) remains inconclusive, and analysis of causality is lacking.

OBJECTIVES

To examine the causal association between long-term O3 exposure and AOA.

METHODS

A prospective cohort study of 362,098 participants was conducted using the UK Biobank study. Incident cases of AOA were identified using health administrative data of the National Health Services. O3 exposure at participants' residential addresses was estimated by a spatio-temporal model. Instrumental variable (IV) modelling was used to analyze the causal association between O3 exposure and AOA, by incorporating wind speed and planetary boundary layer height as IVs into time-dependent Cox model. Negative control outcome (accidental injury) was also used to additionally evaluate unmeasured confounding.

RESULTS

During a mean follow-up of 11.38 years, a total of 10,973 incident AOA cases were identified. A U-shaped concentration-response relationship was observed between O3 exposure and AOA in the traditional Cox models with HR of 0.916 (95% CI: 0.888, 0.945) for O3 at low levels (<38.17 ppb), and 1.204 (95% CI: 1.168, 1.242) for O3 at high levels (≥38.17 ppb). However, in the IV analysis we only found a statistically significant association between high-level O3 exposure and AOA risk, but not for low-level O3 exposure. No significant associations between O3 exposure and accidental injury were observed.

CONCLUSION

Our findings suggest a potential causal relationship between long-term exposure to high-level ambient O3 and increased risks of AOA.

The causal impact of fetal exposure to PM2.5 on birth outcomes: Evidence from rural China

This paper investigates the causal impact of fetal exposure to PM2.5 on birth outcomes, including birth weight, the incidence of low birth weight (LBW), and small for gestational age (SGA), based on a nationally representative birth record dataset in a developing country setting. We employed thermal inversion as the instrument variable (IV) for PM2.5 and leveraged the distinctive characteristics of rural China in the 1990 s to address identification challenges. Our IV estimates indicate that higher fetal PM2.5 exposure leads to lower birth weight and elevated probabilities of LBW and SGA. Due to the mortality selection in utero, weak male fetuses were more likely to be screened out by PM2.5 exposure, resulting in a comparatively lower vulnerability among the surviving male infants. Furthermore, infants born to less educated mothers exhibited increased susceptibility, a phenomenon not entirely explained by the sorting behaviors associated with the preference for cleaner air based on socioeconomic status.

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.

U-shaped relationship between ozone exposure and preterm birth risk associated with preconception telomere length

There are conflicting findings regarding the association of ozone (O3) exposure with preterm birth (PTB) occurrence. In the present study, two cohorts were combined to explore the relationship between maternal O3 exposure during pregnancy and PTB risk, and analyze the underlying mechanisms of this relationship in terms of alterations in the preconception telomere length. Cohort 1 included mothers who participated in the National Free Preconception Health Examination Project in Henan Province from 2014 to 2018 along with their newborns (n = 1,066,696). Cohort 2 comprised mothers who conceived between 2016 and 2018 and their newborns (n = 1871) from six areas in Henan Province. The telomere length was assessed in the peripheral blood of mothers at the preconception stage. Data on air pollutant concentrations were collected from environmental monitoring stations and individual exposures were assessed using an inverse distance-weighted model. O3 concentrations (100.60 ± 14.13 μg/m3) were lower in Cohort 1 than in Cohort 2 (114.09 ± 15.17 μg/m3). Linear analyses showed that PTB risk decreased with increasing O3 exposure concentrations in Cohort 1 but increased with increasing O3 exposure concentrations in Cohort 2. Nonlinear analyses revealed that PTB risk tended to decrease and then increase with increasing O3 exposure concentrations in both cohorts. Besides, PTB risk was reduced by 88% for each-unit increase in telomere length in those exposed to moderate O3 concentrations (92.4-123.7 μg/m3, P < 0.05). While no significant association was observed between telomere length and PTB at extreme O3 concentration exposure during entire pregnancy (<92.4 or >123.7 μg/m3, P > 0.05) in Cohort 2. These findings reveal a nonlinear (U-shaped) relationship between O3 exposure and PTB risk. Furthermore, telomere with elevated length was associated with decreased risk of PTB only when exposed to moderate concentrations of O3, but not when exposed to extreme concentrations of O3 during pregnancy.

Independent and interaction effects of prenatal exposure to high AQI and extreme Humidex on the risk of preterm birth: A large sample population study in northern China

The combined effects of air pollution and extreme temperature on PTB remain unclear. To evaluate the independent effect and interaction effect of prenatal extreme exposure to air quality index (AQI) and Humidex, on PTB. Based on the National Health Care Data Platform of Shandong University, women who gave birth in 2019-2020 were selected for the study. First, the independent effects of AQI and Humidex on PTB were assessed by logistic regression model. Subsequently, the interaction effects of AQI and Humidex on PTB were estimated separately by calculation of the relative excess risk of interaction (RERI). A total of 34365 pregnant women were included and 1975 subjects were diagnosed with PTB. We observed a significant increase in the odds of PTB associated with maternal high AQI exposure, with an OR of 1.70 (95% CI: 1.59, 1.81). Similarly, extreme exposure to Humidex also demonstrated an elevated PTB odds, with a low Humidex OR of 2.48 (95% CI: 2.23, 2.76) and a high Humidex OR of 1.48 (95% CI: 1.31, 1.67). Finally, we observed an interaction between high AQI and extreme Humidex during the 1st trimester. Interaction effects were noted between high AQI and low Humidex throughout the entire trimester and the 2nd trimester. This study suggests that prenatal exposure to high AQI and extreme Humidex could increase the odds of PTB, with effects exhibiting the sensitivity window and a cumulative trend. Additionally, there is an interaction between AQI and Humidex.