Gut microbiota mediates ambient PM2.5 exposure-induced abnormal glucose metabolism via short-chain fatty acids.

PM2.5 exposure has been found to cause gut dysbiosis and impair glucose homeostasis in human and animals, yet their underlying biological connection remain unclear. In the present study, we aim to investigate the biological significance of gut microbiota in PM2.5-induced glucose metabolic abnormalities. Our results showed that microbiota depletion by antibiotics treatment significantly alleviated PM2.5-induced glucose intolerance and insulin resistance, as indicated by the intraperitoneal glucose tolerance test, glucose-induced insulin secretion, insulin tolerance test, insulin-induced phosphorylation levels of Akt and GSK-3ß in insulin sensitive tissues. In addition, faecal microbiota transplantation (FMT) from PM2.5-exposed donor mice successfully remodeled the glucose metabolism abnormalities in recipient mice, while the transplantation of autoclaved faecal materials did not. Faecal microbiota analysis demonstrated that the composition and alpha diversity of the gut bacterial community were altered by PM2.5 exposure and in FMT recipient mice. Furthermore, short-chain fatty acids levels analysis showed that the circulating acetate was significantly decreased in PM2.5-exposed donor and FMT recipient mice, and supplementation of sodium acetate for 3 months successfully improved the glucose metabolism abnormalities induced by PM2.5 exposure. These results indicate that manipulating gut microbiota or its metabolites could be a potential strategy for preventing the adverse health effects of ambient PM2.5.

Continued Rise in Health Burden from Ambient PM2.5 in India under SSP Scenarios Until 2100 despite Decreasing Concentrations.

Forecasting alterations in ambient air pollution and the consequent health implications is crucial for safeguarding public health, advancing environmental sustainability, informing economic decision making, and promoting appropriate policy and regulatory action. However, predicting such changes poses a substantial challenge, requiring accurate data, sophisticated modeling methodologies, and a meticulous evaluation of multiple drivers. In this study, we calculate premature deaths due to ambient fine particulate matter (PM2.5) exposure in India from the 2020s (2016-2020) to the 2100s (2095-2100) under four different socioeconomic and climate scenarios (SSPs) based on four CMIP6 models. PM2.5 concentrations decreased in all SSP scenarios except for SSP3-7.0, with the lowest concentration observed in SSP1-2.6. The results indicate an upward trend in the five-year average number of deaths across all scenarios, ranging from 1.01 million in the 2020s to 4.12-5.44 million in the 2100s. Further analysis revealed that the benefits of reducing PM2.5 concentrations under all scenarios are largely mitigated by population aging and growth. These findings underscore the importance of proactive measures and an integrated approach in India to improve atmospheric quality and reduce vulnerability to aging under changing climate conditions.

Direct Measurement of Aerosol Liquid Water Content: A Case Study in Summer in Nanjing, China.

Aerosol liquid water content (ALWC) affects the mass loading, optical properties, and toxicity of aerosols. However, the measurement of ALWC is very rare due to its requirement of sophisticated instruments and its high operational costs. In this work, we improved on our previous simple, low-cost method by using a combination of one real-time fine particulate matter (PM2.5) monitor and two turbidimeters and successfully applied these for the direct measurement of ALWC in PM2.5 in Nanjing during the summer of 2023. The average ALWC during this measurement period occupied ~1/6 of the total PM2.5 mass, and this contribution was even greater with the elevation in the PM2.5 concentration. The ALWC was, as anticipated, closely related to the relative humidity (RH) and PM2.5 concentrations, but it did not always increase with the air quality index (AQI) due to the fact that polluted periods in summer were often governed by high O3 levels, not PM2.5 levels. The ALWC also had a great impact on visibility; it could decrease the visibility rapidly to hazy conditions when the dry PM2.5 was not high (~30 µg m-3) or the AQI was "good" (75~100), indicating that the air quality classified as "good" using the dry PM2.5 concentration might actually be "lightly polluted" if the ALWC is included. We also found that the air mass originating from Northeast China had the lowest PM2.5 mass concentration yet the highest ALWC values due to its high RH. Moreover, the quantification of ALWC levels can help us understand the solubility/bioavailability and thus the toxic effects of some specific components (for example, heavy metals or organics). Moreover, the influence of ALWC on air quality classifications should also be considered in the assessment of the health effects of air pollution and in public health early warning and protection.

China's carbon-neutral policies will reduce short-term PM2.5-associated excess incidence of cardiovascular diseases.

China's carbon-neutral target could have benefits for ambient fine particulate matter (PM2.5)-associated mortality. Although previous studies have researched such benefits, the potential impact on cardiovascular disease incidence burden is yet to be investigated thoroughly. Here, we first estimate the association between short-term PM2.5 exposure and the incidence of stroke and coronary heart disease (CHD) via a case-crossover study before projecting future changes in short-term PM2.5-associated excess incidence across China from 2025 to 2060 under three different emission scenarios. We find that, compared to the 2015-2020 baseline, average PM2.5 concentrations nationwide in 2060 under SSP119 (an approximation of a carbon-neutral scenario) are projected to decrease by 81.07%. The short-term PM2.5-related excess incidence of stroke and CHD is projected to be reduced to 3,352 cases (95% confidence interval: 939, 5,738)-compared with 34,485 cases under a medium-emissions scenario (SSP245)-and is expected to be accompanied by a 95% reduction in the related economic burden. China's carbon-neutral policies are likely to bring health benefits for cardiovascular disease by reducing short-term PM2.5-related incidence burden.

Fires as a source of annual ambient PM2.5 exposure and chronic health impacts in Europe.

Chronic exposure to ambient PM2.5 is the largest environmental health risk in Europe. We used a chemical transport model and recent exposure response functions to simulate ambient PM2.5, contribution from fires and related health impacts over Europe from 1990 to 2019. Our estimation indicates that the excess death burden from exposure to ambient PM2.5 declined across Europe at a rate of 10,000 deaths per year, from 0.57 million (95 % confidence intervals: 0.44-0.75 million) in 1990 to 0.28 million (0.19-0.42 million) in the specified period. Among these excess deaths, approximately 99 % were among adults, while only around 1 % occurred among children. Our findings reveal a steady increase in fire mortality fractions (excess deaths from fires per 1000 deaths from ambient PM2.5) from 2 in 1990 to 13 in 2019. Notably, countries in Eastern Europe exhibited significantly higher fire mortality fractions and experienced more pronounced increases compared to those in Western and Central Europe. We performed sensitivity analyses by considering fire PM2.5 to be more toxic as compared to other sources, as indicated by recent studies. By considering fire PM2.5 to be more toxic than other PM2.5 sources results in an increased relative contribution of fires to excess deaths, reaching 2.5-13 % in 2019. Our results indicate the requirement of larger mitigation and adaptation efforts and more sustainable forest management policies to avert the rising health burden from fires.

Interplay of Climate Change and Air Pollution- Projection of the under-5 mortality attributable to ambient particulate matter (PM2.5) in South Asia.

Ambient fine particulate matter (PM2.5) pollution is a leading health risk factor for children under- 5 years, especially in developing countries. South Asia is a PM2.5 hotspot, where climate change, a potential factor affecting PM2.5 pollution, adds a major challenge. However, limited evidence is available on under-5 mortality attributable to PM2.5 under different climate change scenarios. This study aimed to project under-5 mortality attributable to long-term exposure to ambient PM2.5 under seven air pollution and climate change mitigation scenarios in South Asia. We used a concentration-risk function obtained from a previous review to project under-5 mortality attributable to ambient PM2.5. With a theoretical minimum risk exposure level of 2.4 µg/m3, this risk function was linked to gridded annual PM2.5 concentrations from atmospheric modeling to project under-5 mortality from 2010 to 2049 under different climate change mitigation scenarios. The scenarios were developed from the Aim/Endues global model based on end-of-pipe (removing the emission of air pollutants at the source, EoP) and 2 °C target measures. Our results showed that, in 2010-2014, about 306.8 thousand under-5 deaths attributable to PM2.5 occurred in South Asia under the Reference (business as usual) scenario. The number of deaths was projected to increase in 2045-2049 by 36.6% under the same scenario and 7.7% under the scenario where EoP measures would be partially implemented by developing countries (EoPmid), and was projected to decrease under other scenarios, with the most significant decrease (81.2%) under the scenario where EoP measures would be fully enhanced by all countries along with the measures to achieve 2 °C target (EoPmaxCCSBLD) across South Asia. Country-specific projections of under-5 mortality varied by country. The current emission control strategy would not be sufficient to reduce the number of deaths in South Asia. Robust climate change mitigation and air pollution control policy implementation is required.

Effects of long-term exposure to ambient PM2.5 on hypertension and role of dietary regulation / 环境与职业医学

Background The contribution of long-term ambient PM2.5 exposure to hypertension should not be ignored. However, the conclusions of whether dietary factors play a role in regulating PM2.5-related hypertension are still inconsistent. Objective To explore the correlation between long-term exposure to ambient PM2.5 and blood pressure indicators (systolic blood pressure, diastolic blood pressure, mean arterial pressure, and pulse pressure) in adults in Ningxia and a potential moderating effect of dietary factors. Methods A set of cross-sectional survey data from March, 2013 to May, 2018 was retrieved from the China Northwest Cohort-Ningxia, and the average ambient PM2.5 concentration in the previous three years was also collected to estimate the long-term exposure of the participants. Binary logistic regression model was used to validate the correlation between long-term exposure to ambient PM2.5 and hypertension in Ningxia, and linear model was used to study the correlation between long-term exposure to ambient PM2.5 and blood pressure indicators (systolic blood pressure, diastolic blood pressure, mean arterial pressure and pulse pressure), and to explore the influence of dietary factors on ambient PM2.5-related hypertension. Results A total of 11470 participants were included in the study, 42.2% male and 57.8% female. The three-year average ambient PM2.5 concentration before the baseline survey was 37.0 μg·m−3. Each 1 μg·m−3 increase in ambient PM2.5 was associated with an increased risk of hypertension (OR=1.111, 95%CI: 1.097, 1.125), and increased systolic blood pressure, diastolic blood pressure, mean arterial pressure, and pulse pressure by 0.886 (95%CI: 0.783, 0.990), 0.570 (95%CI: 0.500, 0.641), 0.676 (95%CI: 0.600, 0.751), and 0.316 (95%CI: 0.243, 0.389) mmHg, respectively. The stratified analysis showed that the OR and 95%CI of hypertension were 1.171 (1.097, 1.254), 1.117 (1.064, 1.174), and 1.160 (1.116, 1.207) respectively for each 1 μg·m−3 increased in PM2.5 with low frequency of vegetable and fruit consumption and salty taste respectively. The OR and 95%CI of hypertension were decreased when the moderate and high frequency of vegetable and fruit intake and moderate and light taste applied, the values were 1.091 (1.062, 1.121) and 1.114 (1.097, 1.131), 1.105 (1.082, 1.129) and 1.111 (1.092, 1.13), 1.115 (1.090, 1.140) and 1.102 (1.083, 1.121) respectively. Compared with low frequency of vegetable and fruit intake and salty taste, the increase degree of ambient PM2.5 related systolic blood pressure, diastolic blood pressure, mean arterial pressure and pulse pressure also decreased in middle and high frequency of vegetable and fruit intake and moderate and light taste. Conclusion Long-term exposure to ambient PM2.5 is significantly associated with increased risks of hypertension and blood pressure in Ningxia area. Increasing the frequency of vegetable and fruit intake and decreasing salty taste may reduce the effect of ambient PM2.5 on hypertension and blood pressure.

The impact of ambient PM2.5 on daily outpatient visits due to chronic obstructive pulmonary disease, among the urban residents of Ningbo city / 中华流行病学杂志

Objective@#To explore the short-term effects of ambient PM2.5 on the outpatient visits of chronic obstructive pulmonary disease (COPD) in Ningbo city.@*Methods@#Through the regional health information platform, number of daily COPD outpatients from the four general hospitals in Ningbo was gathered. Related data on meteorological and air pollution from 2014 to 2016 was also collected. Generalized additive model (GAM) of Possion regression was used to estimate the impact of PM2.5 pollution on COPD outpatients and the lagging effects.@*Results@#In cold (November- April) or warm seasons (May-October), an 10 μg/m3 increase of PM2.5 would result in the excessive number of COPD outpatients as 1.87% (95%CI: 0.98%-2.76%), 2.09% (95%CI: 1.11%-3.08%) and 2.56% (95%CI: 0.56%-4.59%), respectively. In terms of the short-term effects of PM2.5 the strongest was seen in the days of warm season but without delay (P<0.05). The strongest effect appeared at day 4 in cold season and the effect was particularly significant seen in the over 65 year-old group or in the female population. After the introduction of PM10, SO2 and NO2, the concentration of PM2.5, did not show significant effect on the number of hospital visits due to COPD on the same day (P>0.05). The effect of COPD on the fourth day showed a slight change after the lagging, and the effect was statistically significant (P<0.05).@*Conclusion@#The increase of PM2.5 concentration in Ningbo was related to the increase of COPD outpatient numbers. Effective prevention measures should be taken to protect the vulnerable population and to reduce the risk of COPD.