Short-term exposure to PM2.5 and 1.5 million deaths: a time-stratified case-crossover analysis in the Mexico City Metropolitan Area

Association Between Biomass Fuel Use and Depression Symptoms in the Adult Population of Oaxaca, Mexico

BACKGROUND

The impact of biomass fuel exposure on mental health, along with the associated gender disparities, remains largely unexplored. This study aimed to examine the association between biomass fuel use and depressive symptoms in the population of Oaxaca, Mexico, while also identifying gender differences in this relationship.

METHODS

This study used data from the 2022 National Health and Nutrition Survey (ENSANUT). Depressive symptoms, the outcome variable, were assessed using the Center for Epidemiologic Studies Depression Scale (CESD). The primary predictor variable was biomass fuel use, with gender, age, and residency stratum included as covariates. First, a binary logistic regression model was developed to estimate the dichotomous variable "depression symptoms". Subsequently, a second binary logistic regression model was constructed to evaluate potential interactions between the covariates and the predictor variable.

FINDINGS

The sample included 1.4 million adults from Oaxaca, with a prevalence of depressive symptoms of 15%. Biomass fuel was used by 15.4% of the population. The first logistic regression model showed that women (Odds Ratio (OR): 1.249; 95% CI: 1.235-1.263; p < 0.001), individuals aged 60 years and older compared to the younger population group (OR: 12.192; 95% CI: 12.064-12.321; p < 0.001), those residing in rural areas (OR: 1.245; 95% CI: 1.232-1.259; p < 0.001), and individuals using firewood or charcoal for cooking (OR: 1.674; 95% CI: 1.651-1.697; p < 0.001) had higher odds of depressive symptoms. In the second binary logistic regression model, all associations and OR coefficients retained their direction, although the coefficients underwent a slight adjustment following the introduction of the interaction term, indicating the presence of an interaction.

CONCLUSIONS

The study findings suggest a gendered association between biomass fuel exposure and depressive symptoms in the adult population of Oaxaca, with older women and women dwelling in rural areas being the most vulnerable. Interventions aimed at reducing biomass air pollution exposure and strengthening mental health support for women are strongly recommended.

Effects of fine particulate matter bound heavy metals on intentional self-harm deaths in Guangzhou, China, insight from core chemical constituents

Fine particulate matter (PM2.5) is one of the major threats to human health, and may partly responsible for intentional self-harm deaths, while the limited results seemed contradictory. Further analysis on PM2.5 constituents may provide more reliable evidence. Heavy metals are crucial toxic components of PM2.5 that may induce suicide behavior. What role do PM2.5-bound heavy metals play in a threat to intentional self-harm death is still unclear. Two-year data of daily PM2.5-bound heavy metals (including metalloids) and daily intentional self-harm deaths were collected in Guangzhou. Bayesian kernel machine regression, weighted quantile sum, and quantile-based g-computation models were employed to depict the relationships between heavy metals and intentional self-harm deaths. The number of intentional self-harm deaths was 217 and 283 for 2015 and 2016, respectively. A positive correlation was found between the combined effect of the 13 heavy metals and intentional self-harm deaths. Nickel, cadmium, and iron were the primary contributors to this positive correlation. Heavy metal components play significant roles in PM2.5-related intentional self-harm deaths, and targeted source control measures are warranted to protect residents from suicide.

Impact of metabolism-disrupting chemicals and folic acid supplementation on liver injury and steatosis in mother-child pairs

BACKGROUND & AIMS

Scarce knowledge about the impact of metabolism-disrupting chemicals (MDCs) on steatotic liver disease limits opportunities for intervention. We evaluated pregnancy MDC-mixture associations with liver outcomes, and effect modification by folic acid (FA) supplementation in mother-child pairs.

METHODS

We studied ∼200 mother-child pairs from the Mexican PROGRESS cohort, with 43 MDCs measured during pregnancy (estimated air pollutants, blood/urine metals or metalloids, urine high- and low-molecular-weight phthalate [HMWPs, LMWPs] and organophosphate-pesticide metabolites), and serum liver enzymes (ALT, AST) at ∼9 years post-parturition. Outcomes included elevated liver enzymes in children and established clinical scores for steatosis and fibrosis in mothers (i.e.

, AST

ALT, FLI, HSI, FIB-4). Bayesian-weighted quantile sum regression assessed MDC-mixture associations with liver outcomes. We further examined chemical-chemical interactions and effect modification by self-reported FA supplementation.

RESULTS

In children, many MDC-mixtures were associated with liver injury. Per quartile HMWP-mixture increase, ALT increased by 10.1% (95% CI 1.67%, 19.4%) and AST by 5.27% (95% CI 0.80%, 10.1%). LMWP-mixtures and air pollutant-mixtures were associated with higher AST and ALT, respectively. Air pollutant and non-essential metal/element associations with liver enzymes were attenuated by maternal cobalt blood concentrations (p-interactions <0.05). In mothers, only the LMWP-mixture was associated with odds for steatosis (odds ratio = 1.53, 95% CI 1.01-2.28 for HSI >36, and odds ratio 1.62, 95% CI 1.05-2.49 for AST:ALT <1). In mothers and children, most associations were attenuated (null) at FA supplementation ≥600 μg/day (p-interactions <0.05).

CONCLUSIONS

Pregnancy MDC exposures may increase risk of liver injury and steatosis, particularly in children. Adequate FA supplementation and maternal cobalt levels may attenuate these associations.

IMPACT AND IMPLICATIONS

The effects of environmental chemical exposures on steatotic liver diseases are not well understood. In a parallel investigation of mothers and children, we found that pregnancy exposures to metabolism-disrupting chemicals may increase the risk of liver injury and steatosis, especially in the child, and that these associations could be attenuated by higher folic acid and/or cobalt levels. These findings can inform policies to decrease environmental chemical pollution and contribute to the design of clinical interventions addressing the metabolic dysfunction-associated steatotic liver disease epidemic.

Synergistic PM2.5 and O3 control to address the emerging global PM2.5-O3 compound pollution challenges

In recent years, the issue of PM2.5-O3 compound pollution has become a significant global environmental concern. This study examines the spatial and temporal patterns of global PM2.5-O3 compound pollution and exposure risks, firstly at the global and urban scale, using spatial statistical regression, exposure risk assessment, and trend analyses based on the datasets of daily PM2.5 and surface O3 concentrations monitored in 120 cities around the world from 2019 to 2022. Additionally, on the basis of the common emission sources, spatial heterogeneity, interacting chemical mechanisms, and synergistic exposure risk levels between PM2.5 and O3 pollution, we proposed a synergistic PM2.5-O3 control framework for the joint control of PM2.5 and O3. The results indicated that: (1) Nearly 50% of cities worldwide were affected by PM2.5-O3 compound pollution, with China, South Korea, Japan, and India being the global hotspots for PM2.5-O3 compound pollution; (2) Cities with PM2.5-O3 compound pollution have exposure risk levels dominated by ST + ST (Stabilization) and ST + HR (High Risk). Exposure risk levels of compound pollution in developing countries are significantly higher than those in developed countries, with unequal exposure characteristics; (3) The selected cities showed significant positive spatial correlations between PM2.5 and O3 concentrations, which were consistent with the spatial distribution of the precursors NOx and VOCs; (4) During the study period, 52.5% of cities worldwide achieved synergistic reductions in annual average PM2.5 and O3 concentrations. The average PM2.5 concentration in these cities decreased by 13.97%, while the average O3 concentration decreased by 19.18%. This new solution offers the opportunity to construct intelligent and healthy cities in the upcoming low-carbon transition.

Effects of the interaction between cold spells and fine particulate matter on mortality risk in Xining: a case-crossover study at high altitude

Background

With global climate change, the health impacts of cold spells and air pollution caused by PM2.5 are increasingly aggravated, especially in high-altitude areas, which are particularly sensitive. Exploring their interactions is crucial for public health.

Methods

We collected time-series data on meteorology, air pollution, and various causes of death in Xining. This study employed a time-stratified case-crossover design and conditional logistic regression models to explore the association between cold spells, PM2.5 exposure, and various causes of death, and to assess their interaction. We quantitatively analyzed the interaction using the relative excess odds due to interaction (REOI), attributable proportion due to interaction (AP), and synergy index (S). Moreover, we conducted stratified analyses by average altitude, sex, age, and educational level to identify potential vulnerable groups.

Results

We found significant associations between cold spells, PM2.5, and various causes of death, with noticeable effects on respiratory disease mortality and COPD mortality. We identified significant synergistic effects (REOI>0, AP > 0, S > 1) between cold spells and PM2.5 on various causes of death, which generally weakened with a stricter definition of cold spells and longer duration. It was estimated that up to 9.56% of non-accidental deaths could be attributed to concurrent exposure to cold spells and high-level PM2.5. High-altitude areas, males, the older adults, and individuals with lower educational levels were more sensitive. The interaction mainly varied among age groups, indicating significant impacts and a synergistic action that increased mortality risk.

Conclusion

Our study found that in high-altitude areas, exposure to cold spells and PM2.5 significantly increased the mortality risk from specific diseases among the older adults, males, and those with lower educational levels, and there was an interaction between cold spells and PM2.5. The results underscore the importance of reducing these exposures to protect public health.

Microplastics dysregulate innate immunity in the SARS-CoV-2 infected lung

Introduction

Global microplastic (MP) pollution is now well recognized, with humans and animals consuming and inhaling MPs on a daily basis, with a growing body of concern surrounding the potential impacts on human health.

Methods

Using a mouse model of mild COVID-19, we describe herein the effects of azide-free 1 μm polystyrene MP beads, co-delivered into lungs with a SARS-CoV-2 omicron BA.5 inoculum. The effect of MPs on the host response to SARS-CoV-2 infection was analysed using histopathology and RNA-Seq at 2 and 6 days post-infection (dpi).

Results

Although infection reduced clearance of MPs from the lung, virus titres and viral RNA levels were not significantly affected by MPs, and overt MP-associated clinical or histopathological changes were not observed. However, RNA-Seq of infected lungs revealed that MP exposure suppressed innate immune responses at 2 dpi and increased pro-inflammatory signatures at 6 dpi. The cytokine profile at 6 dpi showed a significant correlation with the 'cytokine release syndrome' signature observed in some COVID-19 patients.

Discussion

The findings are consistent with the recent finding that MPs can inhibit phagocytosis of apoptotic cells via binding of Tim4. They also add to a growing body of literature suggesting that MPs can dysregulate inflammatory processes in specific disease settings.

Ambient fine particulate matter constituents and semen quality among adult men in China

Exposure to ambient fine particulate matter (PM2.5) was associated with decreased semen quality, but the relationship between PM2.5 constituents and semen quality was unclear. We recruited 27,824 adult men attending an infertility clinic in Wuhan, China, between 2014 and 2020. We used a four-dimensional spatiotemporal deep forest model to estimate concentrations of PM2.5 mass and its chemical constituents, including organic matter (OM), black carbon (BC), sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), and chloride (Cl-). We employed linear regression models to estimate the association between PM2.5 mass and its constituents with various sperm parameters. Exposure to PM2.5 was associated with a reduction in sperm quality, with a percent change of - 5.69% (95% confidence interval [CI]: -8.53%, -2.85%) for sperm density, - 15.09% (95% CI: -22.24%, -7.94%) for sperm total count, - 1.63% (95% CI: -2.36%, -0.91%) for sperm progressive motility, and - 2.30% (95% CI: -3.04%, -1.55%) for sperm total motility. Among specific constituents, exposure to OM, BC, Cl-, or NO3- was associated with a reduction in these four semen quality parameters. The association was more pronounced among older men or individuals with lower levels of education. Our findings suggest that PM2.5 mass and each constituent were associated with decreased semen quality in adult men.