Temporal distribution of fine particulates (PM₂.₅:PM₁₀), potentially toxic metals, PAHs and Metal-bound carcinogenic risk in the population of Lucknow City, India

The level, source, and health outcome of PM2.5 exposure in Southwest Iran

Introduction

Dusty storms considerably increase airborne particles in dry and semi-dry locations, such as deserts with no plants and strong winds. Therefore, the environment and people are affected severely. Ahvaz, an important metropolis, is often polluted by neighboring nations. The present research studies the concentration, source, and calculation of these particles' effects.

Material and method

For health consequences evaluation, the WHO suggests the Air Quality Health Impact Evaluation Programmed (Air Q 2.2.3). Khuzestan Meteorology Office recorded particulate matter measurements on both hazy and clear days. The data was gathered voluminously in 2023.

Result

According to data collected from Khuzestan province's meteorology documents, 49 days in 2023 had very unsafe air quality. The most polluted months in terms of the number of dust days are as follows: January (14 days) > December (12 days) > November (11 days) > August (5 days) > May (3 days) > September (2 days) > March, February, June, July, October (1 day) > April (0 days). HYSPLIT maps indicate that Iran causes dust in March, the Great Arabian Desert in December and August, Iraq in April, September, and October, Kuwait in January, Turkey in February and July, Egypt in June and May, and Oman in November.

Conclusion

The meteorology database reveals that Ahvaz is highly polluted and that 49 days had unacceptable dust levels. Based on assessments obtained employing the Air Q+ programs, the people of Ahvaz encountered heart disease, respiratory disease, and stroke caused by their exposure to PM2.5 particulates.

Pollution Characteristics of Heavy Metals in PM1 and Source-Specific Health Risks in the Tianjin Airport Community, China

The airport and its surrounding areas are home to a variety of pollution sources, and air pollution is a recognized health concern for local populated regions. Submicron particulate matter (PM1 with an aerodynamic diameter of <1 mm) is a typical pollutant at airports, and the enrichment of heavy metals (HMs) in PM1 poses a great threat to human health. To comprehensively assess the source-specific health effects of PM1-bound HMs in an airport community, PM1 filter samples were collected around the Tianjin Binhai International Airport for 12 h during the daytime and nighttime, both in the spring and summer, and 10 selected HMs (V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) were analyzed. The indicatory elements of aircraft emissions were certified as Zn and Pb, which accounted for more than 60% of the sum concentration of detected HMs. The health risks assessment showed that the total non-cancer risks (TNCRs) of PM1-bound HMs were 0.28 in the spring and 0.23 in the summer, which are lower than the safety level determined by the USEPA, and the total cancer risk (TCR) was 2.37 × 10-5 in the spring and 2.42 × 10-5 in the summer, implying that there were non-negligible cancer risks in the Tianjin Airport Community. After source apportionment with EF values and PMF model, four factors have been determined in both seasons. Consequently, the source-specific health risks were also evaluated by combining the PMF model with the health risk assessment model. For non-cancer risk, industrial sources containing high concentrations of Mn were the top contributors in both spring (50.4%) and summer (44.2%), while coal combustion with high loads of As and Cd posed the highest cancer risk in both seasons. From the perspective of health risk management, targeted management and control strategies should be adopted for industrial emissions and coal combustion in the Tianjin Airport Community.

Atmospheric polycyclic aromatic hydrocarbons in India: geographical distribution, sources and associated health risk-a review

Atmospheric distribution of polycyclic aromatic hydrocarbons and associated human health risks have been studied in India. However, a comprehensive overview is not available in India, this review highlights the possible sources, and associated cancer risks in people living in different zones of India. Different databases were searched for the scientific literature on polycyclic aromatic hydrocarbons in ambient air in India. Database searches have revealed a total of 55 studies conducted at 139 locations in India in the last 14 years between 1996 and 2018. Based on varying climatic conditions in India, the available data was analysed and distributed with four zone including north, east, west/central and south zones. Comparatively higher concentrations were reported for locations in north zone, than east, west/central and south zones. The average concentrations of ∑PAHs is lower in east zone, and concentrations in north, west/central and south zones are higher by 1.67, 1.47, and 1.12 folds respectively than those in east zone. Certain molecular diagnostic ratios and correlation receptor models were used for identification of possible sources, which aided to the conclusion that both pyrogenic and petrogenic activities are the mixed sources of PAH emissions to the Indian environment. Benzo(a)pyrene toxicity equivalency for different zones is estimated and presented. Estimated Chronic daily intake (CDI) due to inhalation of PAHs and subsequently, cancer risk (CR) is found to be ranging from extremely low to low in various geographical zones of India.

Transcriptomics profile of human bronchial epithelial cells exposed to ambient fine particles and influenza virus (H3N2)

Fine particulate matter (PM2.5) pollution remains a major threat to public health. As the physical barrier against inhaled air pollutants, airway epithelium is a primary target for PM2.5 and influenza viruses, two major environmental insults. Recent studies have shown that PM2.5 and influenza viruses may interact to aggravate airway inflammation, an essential event in the pathogenesis of diverse pulmonary diseases. Airway epithelium plays a critical role in lung health and disorders. Thus far, the mechanisms for the interactive effect of PM2.5 and the influenza virus on gene transcription of airway epithelial cells have not been fully uncovered. In this present pilot study, the transcriptome sequencing approach was introduced to identify responsive genes following individual and co-exposure to PM2.5 and influenza A (H3N2) viruses in a human bronchial epithelial cell line (BEAS-2B). Enrichment analysis revealed the function of differentially expressed genes (DEGs). Specifically, the DEGs enriched in the xenobiotic metabolism by the cytochrome P450 pathway were linked to PM2.5 exposure. In contrast, the DEGs enriched in environmental information processing and human diseases, such as viral protein interaction with cytokines and cytokine receptors and epithelial cell signaling in bacterial infection, were significantly related to H3N2 exposure. Meanwhile, co-exposure to PM2.5 and H3N2 affected G protein-coupled receptors on the cell surface. Thus, the results from this study provides insights into PM2.5- and influenza virus-induced airway inflammation and potential mechanisms.

Particle and heavy metal accumulation by two plant species in a coal mining area of Odisha, India

Mining activities lead to severe particulate matter (PM) pollution that consequently has a detrimental effect on ecosystem. A study was therefore conducted in a coal mining area of Odisha, India with an objective to assess the particulate matter pollution on the basis of differential aerodynamic size (PM10 and PM2.5) of the particles, the metallic (Zn and Fe) composition, and also to evaluate their nature of deposition on two identified plant species. The results suggest a significant variation in particle and heavy metal fractions in the ambient air of different sites (p < 0.05). Fe dominated the finer particle (PM2.5) fraction while Zn dominated the coarser counterpart (PM10) in the ambient air. When evaluated for the particle and heavy metal deposition on leaf surface, Shorea robusta performed better in trapping the coarser particles (PM10) while Holarrhena floribunda was found to be an efficient scrubber of the finer particles (PM2.5). Fe deposition on surface of leaves was comparatively higher than Zn irrespective of plant species or size fractions. Therefore, it is concluded that both S. robusta and H. floribunda should be planted in a schematic manner to tackle the particulate pollution in coal mining areas.

Exposure to incense burning, biomarkers, and the physical health of temple workers in Taiwan

Incense burning releases heavy particulate matter (PM) and nitrogen dioxide (NO2), known to have adverse effects on human health. Long-term exposure to PM and NO2 increases inflammatory cytokine levels and can induce respiratory diseases. This study examined the association between incense burning exposure and the health status, especially inflammatory biomarkers, of temple workers and volunteers in Taiwan. The longitudinal observational study compared adult temple workers and volunteers, with long-term incense burning exposure, to residents from outpatient clinics in the Chiayi area. Forced expiratory volume in 1 s (FEV1) and serum and exhaled breath condensate (EBC) cytokines were assessed. Nonparametric Mann-Whitney U tests were used to compare cytokine levels of the exposure and control groups during the cold and hot weather seasons. FEV1 was significantly more diminished in the exposed group than in the control group during the cold season. Exposure status was associated with greater hot-cold seasonal differences in serum interleukins (IL)-1β (regression coefficient (B) = 6.6, 95% confidence interval (CI) = 5.0 to 8.3, p < .001), IL17-A (B = 2.4, 95% CI = 0.3 to 4.5, p = .03), and plasminogen activator inhibitor [PAI]-1 (B = 5.4, 95% CI = 1.5 to 9.3, p = .009). After adjusting for confounders, the groups' serum levels of IL-1β, IL-17A, and PAI-1 significantly differed. EBC cytokines did not show significant differences. Elevated levels of IL-1β, IL17-A, and PAI-1 have been associated with various autoinflammatory syndromes and diseases. Given the cultural significance of incense burning, culturally sensitive interventions, including education, policy development, and program implementation, are crucial to protect individuals' health, especially temple workers, from the adverse effects of exposure, addressing the manufacture, importation, and sale of incense.

Spatial distributions of PM10-bound metal elements in the central part of western Taiwan and their potential emission sources and the carcinogenic health risks

This study aimed to investigate the spatial distribution of metal elements in PM10 and their potential sources and associated health risks over a period of two years in eight locations in the central part of western Taiwan. The study revealed that the mass concentration of PM10 and the total mass concentration of 20 metal elements in PM10 were 39.0 μg m-3 and 4.74 μg m-3, respectively, with total metal elements accounting for approximately 13.0% of PM10. Of the total metal elements, 95.6% were crustal elements (Al, Ca, Fe, K, Mg, and Na), with trace elements (As, Ba, Cd, Cr, Co, Cu, Ga, Mn, Ni, Pb, Sb, Se, V, and Zn) contributing only 4.4%. Spatially, the inland areas exhibited higher PM10 concentrations due to lee-side topography and low wind speeds. In contrast, the coastal regions exhibited higher total metal concentrations because of the dominance of crustal elements from sea salt and crustal soil. Four primary sources of metal elements in PM10 were identified as sea salt (58%), re-suspended dust (32%), vehicle emissions and waste incineration (8%), and industrial emissions and power plants (2%). The positive matrix factorization (PMF) analysis results indicated that natural sources like sea salt and road dust contributed up to 90% of the total metal elements in PM10, while only 10% was attributed to human activities. The excess cancer risks (ECRs) associated with As, Co, and Cr(VI) were greater than 1 × 10-6, and the total ECR was 6.42 × 10-5. Although only 10% of total metal elements in PM10 came from human activities, they contributed to 82% of the total ECR.

Characterization of Polycyclic Aromatic Hydrocarbons (PAHs) associated with fine aerosols in ambient atmosphere of high-altitude urban environment in Sikkim Himalaya

Polycyclic Aromatic Hydrocarbons (PAHs) compounds are ubiquitous in ambient air due to their persistence, carcinogenicity, and mutagenicity. Gangtok being one of the cleanest cities in India located in Eastern Himalayan region, witnesses high developmental activities with enhanced urbanization affecting the ambient air quality. The present study aims to measure PM_2.5 and PAHs in the ambient atmosphere of the Sikkim Himalaya to understand the influence of natural and anthropogenic activities on aerosol loading and their chemical characteristics. The PM_2.5 samples were collected and analysed for the duration from Jan 2020 to Feb 2021.The seasonal mean concentrations of PM_2.5 and PAHs were observed to be high during autumn and low during summer season. Overall, the annual mean concentration of PM_2.5 was found higher than the prescribed limit of World Health Organization and National Ambient Air Quality Standards. The concentration of the 16 individual PAHs were found to be highest during autumn season (55.26 ± 37.15 ng/m³). Among the different PAHs, the annual mean concentration of fluorene (3.29 ± 4.07 ng/m³) and naphthalene (1.15 ± 3.76 ng/m³) were found to be the highest and lowest, respectively. The Molecular Diagnostic Ratio (MDR) test reveals higher contribution from heavy traffic activities throughout the winter and autumn seasons. The other possible sources identified over the region are fossil fuel combustion, and biomass burning. The multivariate statistical analysis (Multifactor Principal Component Analysis) also indicates a strong association between PM_2.5 /PAHs and meteorological variables across the region in different seasons. The precipitation and wind pattern during the study period suggests that major contribution of the PM_2.5 and PAHs were from local sources, with minimal contribution from long-range transport. The findings are important for comprehending the trends of PAH accumulation over a high-altitude urban area, and for developing sustainable air quality control methods in the Himalayan region.

Heavy metal content and health risk assessment of atmospheric particles in China: A meta-analysis

In recent decades, China has devoted significant attention to the heavy metals pollution in particulate matter. However, the majority of studies have only focused on the field monitoring in relatively remote areas, which may not be representative of air quality across the country. This study reevaluated the characteristics, temporal and spatial changes, and health concerns associated with heavy metal pollution in atmospheric particulates on a national scale by coupling Meta-analysis and Monte Carlo simulation analysis. In terms of spatial distribution, the heavy metals pollution levels in the northern coast and northeastern regions are relatively high, whereas it is low along the middle Yellow River, middle Yangtze River, as well as Southwest. With the exception of Cu, the distribution of all elements in PM2.5 steadily decreased over time Moreover, PM10 and PM2.5 performed similar where Cd and Ni both first increased followed by a decline while, Cr displayed a decrease before it showed an increment. And since the implementation of prevention and control policies about the atmospheric release, the focus of industrial emission has gradually shifted from energy production and processing to living products manufacturing. Moreover, the carcinogenic risk was shown to be Cr > As, Pb > Ni, Cd, while the non-carcinogenic risk was as follows: As, Ni > Cr, Cd. Among all contaminants, Cd, As, and Cr in PM2.5 and PM10 exceeded the WHO standard in the cities with worst air quality. It was observed that As posed the largest non-carcinogenic risk to adults while, Cr caused the most carcinogenic risk to adults and children, where the carcinogenic risk of children remains higher than that of adults. Therefore, the findings of this study may offer data support to the China's heavy metal pollution standards in airborne particles and offer theoretical data support for pollution management.

Health effects of PM2.5 constituents and source contributions in major metropolitan cities, South Korea

Ambient PM_2.5 is one of the major risk factors for human health, and is not fully explained solely by mass concentration. We examined the short-term associations of cause-specific mortality (i.e., all-cause, cardiovascular, and respiratory mortality) with the 15 chemical constituents and sources of PM_2.5 in four metropolitan cities of South Korea during 2014-2018. We found transition metals consistently showed significant associations with all-cause mortality, while the effects of other constituents varied across the cities and for cause of death. Carbonaceous components strongly affected the all-cause, cardiovascular, and respiratory mortality in Daejeon. Secondary inorganic aerosols, SO₄^2- and NH₄⁺, showed significant associations with respiratory mortality in Gwangju. We also found the sources from which species closely linked to mortality generally increased the relative mortality risks. Heavy metal markers from soil or industrial sources were significantly associated with mortality in all cities. However, several sources influenced mortality despite their marker species not being significantly associated with it. Secondary nitrate and secondary sulfate sources were linked to mortality in DJ. This could be attributed to the deep inland location, which might have facilitated formation of secondary inorganic aerosols. In addition, primary sources including mobile and coal combustion seemed to have acute impacts on respiratory mortality in Gwangju. Our findings suggest the necessity of positive matrix factorization (PMF)-based approaches for evaluating health effects of PM_2.5 while considering the spatial heterogeneity in the compositions and source contributions of PM_2.5.

Long-term PM2.5 exposure in association with chronic respiratory diseases morbidity: A cohort study in Northern China

Several literatures have examined the risk of chronic respiratory diseases in association with short-term ambient PM2.5 exposure in China. However, little evidence has examined the chronic impacts of PM2.5 exposure on morbidity of chronic respiratory diseases in cohorts from high pollution countries. Our study aims to investigate the associations. Based on a retrospective cohort among adults in northern China, a Cox regression model with time-varying PM2.5 exposure and a concentration-response (C-R) curve model were performed to access the relationships between incidence of chronic respiratory diseases and long-term PM2.5 exposure during a mean follow-up time of 9.8 years. Individual annual average PM2.5 estimates were obtained from a satellite-based model with high resolution. The incident date of a chronic respiratory disease was identified according to self-reported physician diagnosis time and/or intake of medication for treatment. Among 38,047 urban subjects analyzed in all-cause chronic respiratory disease cohort, 482 developed new cases. In CB (38,369), asthma (38,783), and COPD (38,921) cohorts, the onsets were 276, 89, and 14, respectively. After multivariable adjustment, hazard ratio and 95% confidence interval for morbidity of all-cause chronic respiratory disease, CB, asthma, and COPD were 1.15 (1.01, 1.31), 1.20 (1.00, 1.42), 0.76 (0.55, 1.04), and 0.66 (0.29, 1.47) with each 10 μg/m3 increment in PM2.5, respectively. Stronger effect estimates were suggested in alcohol drinkers across stratified analyses. Additionally, the shape of C-R curve showed an increasing linear relationship before 75.00 μg/m3 concentrations of PM2.5 for new-onset all-cause chronic respiratory disease, and leveled off at higher levels. These findings indicated that long-term exposure to high-level PM2.5 increased the risks of incident chronic respiratory diseases in China. Further evidence of C-R curves is warranted to clarify the associations of adverse chronic respiratory outcomes involving air pollution.

Can the Indian national ambient air quality standard protect against the hazardous constituents of PM2.5?

Globally, exposure to ambient fine particulate matter (PM_2.5) pollution claims ∼9 million lives, yearly, and a quarter of this deaths occurs in India. Regulation of PM_2.5 pollution in India is based on compliance with its National Ambient Air Quality Standard (NAAQS) of 40 μg/m³, which is eight times the revised global air quality guideline (AQG) of 5 μg/m³. But, whether the NAAQS provides adequate protection against the hazardous components in PM_2.5 is still not clear. Here, we examined the risk to health associated with exposure to PM_2.5-bound polychlorinated biphenyls (PCB), heavy metals and polycyclic aromatic hydrocarbons (PAHs) in an Indian district averaging below the NAAQS. The annual average concentrations of PM_2.5 mass, Σ₂₈PCB and Σ₁₃PAHs were 34 ± 17 μg/m³, 21 ± 12 ng/m³ and 458 ± 246 ng/m³, respectively. Concentrations of As, Cr, Mn and Ni in PM_2.5 surpassed the screening levels for residential air. Substantial level of risks to health were associated with exposure to dioxin-like PCBs (Σ₁₂dlPCB), PAHs, As, Cr and Ni. The hazard index or lifetime cancer risk were 240, or 9 cases per 1000 population, respectively. The estimated risks to health through exposure to hazardous components, except Ni, were greatest in rural areas, having a lower average PM_2.5 concentration, than urban or peri-urban areas, suggesting higher toxicity potential of rural combustion sources. The large disparity between the estimated risk values and the acceptable risk level suggests that it would take a more stringent standard, such as the global AQG, to protect vulnerable populations in India from hazardous components in PM_2.5.

Characteristics of particle-bound polycyclic aromatic hydrocarbons (PAHs) in indoor PM2.5 of households in the Southwest part of Ulaanbaatar capital, Mongolia

Air pollution, including PM_2.5 concentration in Ulaanbaatar (capital of Mongolia) is a serious matter of concern. As the majority of households use coal in large areas of the city, indoor air quality is also posing a serious risk to human health. This study investigated the concentration of polycyclic aromatic compounds (PAHs) in indoor particulate matter (PM_2.5) in 10 non-smoker households. Sampling was conducted in winter of 2018, between 27 January and 09 February. Concentrations of PM_2.5 in the indoor air of households ranged between 62.8 and 324.8 µg m^-3. Total concentration of PAHs also varied in a relatively wide range, between 46.2 and 175.7 ng m^-3. Five-ring PAHs represented a considerably high fraction of total PAHs between 25 and 53%, benzo[b]fluoranthene (BbF) and benzo[a]pyrene (BaP) were the two predominant compounds within five-ring PAHs. Significant correlation was found between indoor and outdoor particulate matter levels in wintertime. Considering individual characteristic PAHs, heavier PAHs homologues (4- to 5-ring and 6-ring PAHs) were detected in all households, which suggested the influence of coal combustion and traffic exhaust. Health risk of children attributed to PAHs inhalation was assessed by taking into account the lifetime-average daily dose (LADD) and corresponding lifetime cancer risk. Lifetime average daily dose for children in only one household were slightly higher than health-based guideline level (1.0 × 10^-5), defined by WHO, whereas LADD for adults and children of other households were within acceptable limit. The cancer risks from the exposure of children to air pollutants in all households except HH-3 were found high. In the Vibrio fischeri bioluminescence inhibition assay, according to the toxic unit (TU) values of indoor PM_2.5 from ten households, all samples were classified as toxic.

Adverse Effects of fine particulate matter on human kidney functioning: a systematic review

BACKGROUND

Ambient fine particulate matter (PM < 2.5 μm, PM2.5) is gaining increasing attention as an environmental risk factor for health. The kidneys are considered a particularly vulnerable target to the toxic effects that PM2.5 exerts. Alteration of kidney function may lead to a disrupted homeostasis, affecting disparate tissues in the body. This review intends to summarize all relevant knowledge published between January 2000 and December 2021 on the effects of ambient PM2.5 and the adverse effects on kidney function in adults (≥ 18 years).

RESULTS AND DISCUSSION

Studies published in peer-reviewed journals, written in English, regarding the effects of PM2.5 on kidney function and the development and/or exacerbation of kidney disease(s) were included. Of the 587 nonduplicate studies evaluated, 40 were included, comprising of studies on healthy or diagnosed with pre-existing disease (sub)populations. Most of the studies were cohort studies (n = 27), followed by 10 cross-sectional, 1 ecological and 2 time-series studies. One longitudinal study was considered intermediate risk of bias, the other included studies were considered low risk of bias. A large portion of the studies (n = 36) showed that PM2.5 exposure worsened kidney outcome(s) investigated; however, some studies show contradictory results. Measurement of the estimated glomerular filtration rate, for instance, was found to be positively associated (n = 8) as well as negatively associated (n = 4) with PM2.5.

LIMITATIONS AND CONCLUSION

The main limitations of the included studies include residual confounding (e.g., smoking) and lack of individual exposure levels. The majority of included studies focused on specific subpopulations, which may limit generalizability. Evidence of the detrimental effects that ambient PM2.5 may exert on kidney function is emerging. However, further investigations are required to determine how and to what extent air pollution, specifically PM2.5, exerts adverse effects on the kidney and alters its function.

REGISTRATION

The systematic review protocol was submitted and published by the International Prospective Register of Systematic Reviews (PROSPERO; CRD42020175615 ).

Short-term associations between particulate matter air pollution and hospital admissions through the emergency room for urinary system disease in Beijing, China: A time-series study

Evidence on the relationship between particulate matter air pollution and urinary system disease (UD) is scarce. This study aims to evaluate the associations between short-term exposures to PM_2.5 and PM₁₀ and risk of daily UD inpatient hospital admissions through the emergency room (ER-admissions) in Beijing. We obtained 41,203 weekday UD ER-admissions for secondary and tertiary hospitals in all 16 districts in Beijing during 2013-2018 from the Beijing Municipal Health Commission Information Center and obtained district-level air pollution concentrations based on 35 fixed monitoring stations in Beijing. We conducted a two-stage time-series analysis, with district-specific generalized linear models for each of Beijing's 16 districts, followed by random effects meta-analysis to obtain pooled risk estimates. We evaluated lagged and cumulative associations up to 30 days. In single-pollutant models, for both PM_2.5 and PM₁₀, cumulative exposure averaged over the day of admission and the previous 10 days (lag 0-10 days) showed the strongest association, with per interquartile range increases of PM_2.5 or PM₁₀ concentrations associated with a 7.5 % (95 % confidence interval [CI]: 3.0 %-12.2 %) or 6.0 % (95 % CI: 1.1 %-11.2 %) increased risk of daily UD hospital admissions, respectively. The risk estimates were robust to adjustment for co-pollutants and to a variety of sensitivity analyses. However, due to the strong correlation between PM_2.5 and PM₁₀ concentrations, we were unable to disentangle the respective relationships between these two exposures and UD risk. In this study, we found that short-term exposures to PM_2.5 and PM₁₀ are risk factors for UD morbidity and that cumulative exposure to PM pollution over a period of one to two weeks (i.e., 11 days) could be more important for UD risk than transient exposure during each of the respective single days.

Research advances in pathogenic mechanisms underlying air pollution-induced ocular surface diseases

Background

The harmful effect of aerial fine particulate matter（PM2.5）has been a serious public health issue and has attracted worldwide attention, especially in developing countries.

Main Text

Numerous previous clinical and experimental studies have demonstrated that PM2.5 has a clear pathogenic effect on diseases related to the respiratory and cardiovascular systems. Recent researches have pointed out that PM2.5 plays a pivotal role in the occurrence and progression of ocular surface diseases. The current studies have shown that PM2.5 may promote the appearance of conjunctivitis, keratitis, blepharitis, dry eye, meibomian gland dysfunction（MGD） and other ocular surface diseases through regulating a series of mechanisms such as inflammation, immune reaction, oxidative stress, autophagy, cell migration, and epigenetics.

Conclusions

This review aims to summarize the current research progress on the pathogenic mechanism of PM2.5-related ocular surface diseases.

Season, not lockdown, improved air quality during COVID-19 State of Emergency in Nigeria

Globally, ambient air pollution claims ~9 million lives yearly, prompting researchers to investigate changes in air quality. Of special interest is the impact of COVID-19 lockdown. Many studies reported substantial improvements in air quality during lockdowns compared with pre-lockdown or as compared with baseline values. Since the lockdown period coincided with the onset of the rainy season in some tropical countries such as Nigeria, it is unclear if such improvements can be fully attributed to the lockdown. We investigate whether significant changes in air quality in Nigeria occurred primarily due to statewide COVID-19 lockdown. We applied a neural network approach to derive monthly average ground-level fine aerosol optical depth (AODf) across Nigeria from year 2001-2020, using the Multi-angle Implementation of Atmospheric Correction (MAIAC) AODs from Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) satellites, AERONET aerosol optical properties, meteorological and spatial parameters. During the year 2020, we found a 21% or 26% decline in average AODf level across Nigeria during lockdown (April) as compared to pre-lockdown (March), or during the easing phase-1 (May) as compared to lockdown, respectively. Throughout the 20-year period, AODf levels were highest in January and lowest in May or June, but not April. Comparison of AODf levels between 2020 and 2019 shows a small decline (1%) in pollution level in April of 2020 compare to 2019. Using a linear time-lag model to compare changes in AODf levels for similar months from 2002 to 2020, we found no significant difference (Levene's test and ANCOVA; α = 0.05) in the pollution levels by year, which indicates that the lockdown did not significantly improve air quality in Nigeria. Impact analysis using multiple linear regression revealed that favorable meteorological conditions due to seasonal change in temperature, relative humidity, planetary boundary layer height, wind speed and rainfall improved air quality during the lockdown.

Spatio-temporal assessment of ambient air quality, their health effects and improvement during COVID-19 lockdown in one of the most polluted cities of India

The present work aims to investigate seasonal variations in air pollution levels in Lucknow and assess the ambient air quality of the city together with highlighting the health impacts of major pollutants like PM10, PM2.5, SO2, NO2, Pb, Ni and aerosols from 2010 to 2019. The maximum and minimum values of PM10, PM2.5, SO2, NO2, Pb and Ni were found to be 270.75 and 122.45 μg/m3, 124.95 and 95.52 μg/m3, 25.60 and 8.05 μg/m3, 75.65 and 23.85 μg/m3, 0.66 and 0.03 μg/m3 and 0.07 and 0.01 ng/m3, respectively. Health impact of particulate matter has also been assessed with AirQ+, and it was estimated that long-term exposure of PM10 was attributed to between 37 and 48% for post-neonatal (age 1-12 months) mortality rate due to all causes, whereas long-term attributable proportions in mortality due to exposure of PM2.5 were to about 19 to 28% from all causes. Further, an attempt has also been made to evaluate the impact of lockdown amid COVID-19 on the ambient air quality of Lucknow. During the lockdown, PM2.5 levels reduced by 65% (at Gomti Nagar), 23% (at central school), 79% (at Lalbagh) and 35% (at Talkatora), due to which, air quality index of Gomti Nagar came down to 43, well below 50 which falls in the healthy range. NO2 levels also came down. However, levels of SO2 did not show significant reduction. Correlating the data between aerosol optical depth and Angstrom exponent by Pearson correlation analysis revealed a significant positive correlation (r = 0.65, P < 0.001).

Human health risk assessment for toxic elements in the extreme ambient dust conditions observed in Sistan, Iran

This study evaluates the bioaccessibility and health risks related to heavy metals (Cd, Cr, Co, Cu, Mn, Ni, Pb, Zn and metalloid As) in airborne dust samples (TSP and PM_2.5) in Zabol, Iran during the summer dust period, when peak concentration levels of PM are typically observed. High bioaccessibilities of carcinogenic metals in PM_2.5 (i.e. 53.3%, 48.6% and 47.6% for Ni, Cr and As, respectively) were calculated. The carcinogenic and non-carcinogenic health risks were assessed for three exposure pathways (inhalation, ingestion and dermal contact), separately for children and adults. Non-carcinogenic inhalation risks were very high (Hazard Index: HI > 1) both for children and adults, while the carcinogenic risks were above the upper acceptable threshold of 10^-4 for adults and marginally close (5.0-8.4 × 10^-5) for children. High carcinogenic risks (>10^-4) were found for the ingestion pathway both for children and adults, while HI values > 1 (8.2) were estimated for children. Carcinogenic and non-carcinogenic risk estimates for dermal contact were also above the limits considered acceptable, except for the carcinogenic risk for children (7.6 × 10^-5). Higher non-carcinogenic and carcinogenic risks (integrated for all elements) were associated with the inhalation pathway in adults and children with the exception of carcinogenic risk for children, where the ingestion route remains the most important, while As was linked with the highest risks for nearly all exposure pathways. A comparative evaluation shows that health risks related with toxic elements in airborne particles in Sistan are among the highest reported in the world.

Chemical characteristics and sources of ambient PM2.5 in a harbor area: Quantification of health risks to workers from source-specific selected toxic elements

Samples of ambient PM_2.5 were collected in the Qingdao harbor area between 21 March and May 25, 2016, and analyzed to investigate the compositions and sources of PM_2.5 and to assess source-specific selected toxic element health risks to workers via a combination of positive matrix factorization (PMF) and health risk (HR) assessment models. The mean concentration of PM_2.5 in harbor area was 48 μg m^-3 with organic matter (OM) dominating its mass. Zn and V concentrations were significantly higher than the other selected toxic elements. The hazard index (HI) and cancer risk (R_i) of all selected toxic elements were lower than the United States Environmental Protection Agency (USEPA) limits. There were no non-cancer and cancer risks for workers in harbor area. The contributions from industrial emissions (IE), ship emissions (SE), vehicle emissions (VE), and crustal dust and coal combustion (CDCC) to selected toxic elements were 39.0%, 12.8%, 24.0%, and 23.0%, respectively. The HI values of selected toxic elements from IE, CDCC, SE, and VE were 1.85 × 10^-1, 7.08 × 10^-2, 6.36 × 10^-2, and 3.37 × 10^-2, respectively; these are lower than the USEPA limits. The total cancer risk (R_t) value from selected toxic elements in CDCC was 2.04 × 10^-7, followed by IE (6.40 × 10^-8), SE (2.26 × 10^-8), and VE (2.18 × 10^-8). CDCC and IE were the likely sources of cancer risk in harbor area. The Bo Sea and coast were identified as the likely source areas for health risks from IE via potential source contribution function (PSCF) analysis based on the results of PMF-HR modelling. Although the source-specific health risks were below the recommended limit values, this work illustrates how toxic species in PM_2.5 health risks can be associated with sources such that control measures could be undertaken if the risks warranted it.

Particulate matter exchange between atmosphere and roads surfaces in urban areas

The deposition and the re-suspension of particulate matter (PM) in urban areas are the key processes that contribute not only to stormwater pollution, but also to air pollution. However, investigation of the deposition and the re-suspension of PM is challenging because of the difficulties in distinguishing between the resuspended and the deposited PM. This study created two Bayesian Networks (BN) models to explore the deposition and the re-suspension of PM as well as the important influential factors. The outcomes of BN modelling revealed that deposition and re-suspension of PM10 occurred under both, high-traffic and low-traffic conditions, and the re-suspension of PM2.5 occurred under low-traffic conditions. The deposition of PM10 under low-volume traffic condition is 1.6 times higher than under high-volume traffic condition, which is attributed to the decrease in PM10 caused by relatively higher turbulence under high-volume traffic conditions. PM10 is more easily resuspended from road surfaces compared to PM2.5 as the particles which larger than the thickness of the laminar airflow over the road surface are more easily removed from road surfaces. The increase in wind speed contributes to the increase in PM build-up by transporting particulates from roadside areas to the road surfaces and the airborne PM2.5 and PM10 increases with the increase in relative humidity. The study outcomes provide a step improvement in the understanding of the transfer processes of PM2.5 and PM10 between atmosphere and urban road surfaces, which in turn will contribute to the effective design of mitigation measures for urban stormwater and air pollution.

PM2.5 impairs macrophage functions to exacerbate pneumococcus-induced pulmonary pathogenesis

Background

Pneumococcus is one of the most common human airway pathogens that causes life-threatening infections. Ambient fine particulate matter (PM) with aerodynamic diameter ≤ 2.5 μm (PM_2.5) is known to significantly contribute to respiratory diseases. PM_2.5-induced airway inflammation may decrease innate immune defenses against bacterial infection. However, there is currently limited information available regarding the effect of PM_2.5 exposure on molecular interactions between pneumococcus and macrophages.

Results

PM_2.5 exposure hampered macrophage functions, including phagocytosis and proinflammatory cytokine production, in response to pneumococcal infection. In a PM_2.5-exposed pneumococcus-infected mouse model, PM_2.5 subverted the pulmonary immune response and caused leukocyte infiltration. Further, PM_2.5 exposure suppressed the levels of CXCL10 and its receptor, CXCR3, by inhibiting the PI3K/Akt and MAPK pathways.

Conclusions

The effect of PM_2.5 exposure on macrophage activity enhances pneumococcal infectivity and aggravates pulmonary pathogenesis.

The influence of PM2.5 on lung injury and cytokines in mice

Exposure to particulate matter ≤2.5 µm in diameter (PM_2.5) profoundly affects human health. However, the role of PM_2.5 on lung injury and cytokine levels in mice is currently unknown. The aim was to examine the effect of PM_2.5 pollution on lung injury in mice fed at an underground parking lot. A total of 20 female Kunming mice were randomly divided into control and polluted groups, with 10 rats in each group. The control group was kept in the laboratory, while the pollution group was fed in an underground parking lot. The concentrations of pollutants were measured using ambient air quality monitoring instruments. After 3 months of treatment, the lungs were collected and examined using electron microscopy, and the morphological structures were assessed using hematoxylin and eosin staining. The polarization of macrophages was evaluated by immunofluorescence. The concentration of interleukin (IL)-4, tumor necrosis factor (TNF)-α and transforming growth factor (TGF)-β1 in peripheral sera were assessed by ELISA. The mRNA and protein levels of IL-4, TNF-α, and TGF-β1 in lung tissues were assessed by reverse transcription-quantitative polymerase chain reaction and western blot analyses, respectively. In the polluted group, the levels of CO, NO_x and PM_2.5 were significantly higher compared with the control group. Compared with the controls, intracellular edema, an increased number of microvilli and lamellar bodies, smaller lamellar bodies in type II alveolar epithelial cells, and abundant particles induced by PM_2.5 in macrophages were observed in the polluted group. The lung ultrastructure changed in the polluted group, revealing exhaust-induced lung injury: The tissues were damaged, and the number of inflammatory cells, neutrophils, polylymphocytes and eosinophils increased in the polluted group compared with the control group. The authors also observed that the number of M1 and M2 macrophages markedly increased after the exhaust treatment. The levels of IL-4, TNF-α and TGF-β1 in the sera and tissues were significantly increased in the polluted group. PM_2.5 pollutants in underground garages can lead to lung injury and have a significant impact on the level of inflammatory cytokines in mice. Therefore, the authors suggest that PM_2.5 can activate the inflammatory reaction and induce immune dysfunction, leading to ultrastructural damage.

Chemical fractionation, bioavailability, and health risks of heavy metals in fine particulate matter at a site in the Indo-Gangetic Plain, India

In the present study, the distribution and chemical fractionation of heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in PM_2.5 collected at Sikandarpur in Agra from September 2015 to February 2016 were carried out to evaluate their mobility potential, environmental, and human health risk through inhalation. Sequential extraction procedure was applied to partition the heavy metals into four fractions (soluble and exchangeable fraction (F1); carbonates, oxides, and reducible fraction (F2); bound to organic matter, oxidizable, and sulphidic fraction (F3); and residual fraction (F4)) in PM_2.5 samples. The metals in each fraction were analyzed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Daily PM_2.5 concentration ranged between 13 and 238 μg m^-3 during the study period. For more than 92% of the days, the mass concentrations were greater than the National Ambient Air Quality Standard (NAAQS) set at 60 μg m^-3. The total mass concentration of the eight metals was 3.3 μg m^-3 that accounted for 2.5% of the PM_2.5 mass concentration and followed the order Fe > Zn > Cu > Mn > Pb > Ni > Cd > Cr in dominance. The carcinogenic metals (Cd, Cr, Ni, and Pb) comprised 10% of the total metal determined. Almost all the metals had the highest proportion in the residual fraction (F4) except Ni, which had the highest proportion in the reducible fraction (F2). Chemical fractionation and contamination factor (CF) showed that Pb and Ni are readily mobilized and more bioavailable. Risk assessment code (RAC) showed that Cd, Cu, Mn, Ni, Pb, and Zn had medium environmental risk, while Cr and Fe had low risk. When the bioavailable (F1 + F2) concentrations were applied to calculate non-carcinogenic and carcinogenic risk, the results showed that the value of hazard index (HI) for toxic metals was 1.7 for both children and adults through inhalation. The integrated carcinogenic risk was 1.8 × 10^-6 for children and 7.3 × 10^-6 for adults, with both values being higher than the precautionary criterion (1 × 10^-6). Enrichment factor (EF) calculations showed that Cd, Pb, Zn, and Ni were enriched being contributed by anthropogenic activities carried out in the industrial sectors of the city.

Genotoxic effects of PM10 and PM2.5 bound metals: metal bioaccessibility, free radical generation, and role of iron

The present study was undertaken to examine the possible genotoxicity of ambient particulate matter (PM₁₀ and PM_2.5) in Pune city. In both size fractions of PM, Fe was found to be the dominant metal by concentration, contributing 22% and 30% to the total mass of metals in PM₁₀ and PM_2.5, respectively. The speciation of soluble Fe in PM₁₀ and PM_2.5 was investigated. The average fraction of Fe³⁺ and Fe²⁺ concentrations in PM_2.5 was 80.6% and 19.3%, respectively, while in PM_2.5 this fraction was 71.1% and 29.9%, respectively. The dominance of Fe(III) state in both PM fractions facilitates the generation of hydroxyl radicals (^·OH), which can damage deoxyribose nucleic acid (DNA), as was evident from the gel electrophoresis study. The DNA damage by ^·OH was supported through the in silico density functional theory (DFT) method. DFT results showed that C8 site of guanine (G)/adenine (A) and C6 site of thymine (T)/cytosine (C) would be energetically more favorable for the attack of hydroxyl radicals, when compared with the C4 and C5 sites. The non-standard Watson-Crick base pairing models of oxidative products of G, A, T and C yield lower-energy conformations than canonical dA:dT and dG:dC base pairing. This study may pave the way to understand the structural consequences of base-mediated oxidative lesions in DNA and its role in human diseases.

PM2.5 levels strongly associate with multiple sclerosis prevalence in the Province of Padua, Veneto Region, North-East Italy

Background:

Incidence and prevalence trends of multiple sclerosis (MS) in the Province of Padua, North-East Italy, suggest that environmental factors may be associated with increased MS risk.

Objective:

To investigate the association of PM2.5 with MS prevalence in one of the most polluted geographical area of Italy.

Methods:

In total, 1435 Italian MS patients residing in the Province of Padua were enrolled. The province surface was classified into urban areas, isolated villages, industrialized places, and countryside. Satellite-derived dust-free and sea salt-free PM2.5 concentrations (annual average 1998–2015, μg/m3) allowed the identification of 18 classes of territorial sections with statistically evaluable numbers of inhabitants. Possible correlations between residential locality types, PM2.5 concentrations, and MS prevalence were investigated.

Results:

MS prevalence was significantly ( p < 0.0001) higher in urban areas (ranging from 219 in Padua City to 169/100,000 in other urban areas) compared to isolated villages (116/100,000) or rural domains (109/100,000) and strongly correlated with the annual average concentration of PM2.5 ( r = 0.81, p < 0.001). Regression analysis further associated MS cases with PM.2.5 average concentration ( β = 0.11, p < 0.001).

Conclusion:

In the Province of Padua, MS prevalence is strongly associated with PM2.5 exposure suggesting that air pollutants may be one of the possible environmental risk factors for MS.

PAHs in fine particles over Xi'an, a typical northwestern city in China: sources, distribution, and controlling factors

Levels of particle-bound polycyclic aromatic hydrocarbons (PAHs) are affected by emission as well as multiple factors. In this study, we investigated the sources, uptake, affinity, and removal mechanism of PAHs in fine particles (PM2.5). The source strength was analyzed with source apportionment, which was conducted by principal component analysis (PCA), positive matrix factorization (PMF) and diagnostic ratio analysis. The octanol-air and soot-air partitioning model was used to elucidate the partitioning behavior of PM2.5 PAHs. And the chemical reactivity of PM2.5 PAHs was analyzed to explain PAH removal from particles. Coal combustion, biomass burning, and vehicle emissions comprised the major sources of PAHs. The process of partitioning was thermally controlled and component-dependent. Heterogeneous reactions with NO2, OH, and O3, as well as the aqueous reaction, effectively reduced PM2.5 PAH levels. The systematic analysis combined with field observations revealed that the emission strength is the dominant factor controlling PM2.5 PAH distribution. The source strength governed the levels of PM2.5 PAHs, though uptake, partitioning behavior, chemical removal kinetics, and peripheral conditions had a non-ignorable impact. Heterogeneous and aqueous reactions were the dominant mechanisms of PAH removal from particles. This research provides a comprehensive insight into controlling factors on PM2.5 PAH distribution in Xi'an, as well as a theoretical basis for critical steps to control PAH levels.

Size distribution and source of heavy metals in particulate matter on the lead and zinc smelting affected area

In order to understand the size distribution and the main kind of heavy metals in particulate matter on the lead and zinc smelting affected area, particulate matter (PM) and the source samples were collected in Zhuzhou, Hunan Province from December 2011 to January 2012 and the results were discussed and interpreted. Atmospheric particles were collected with different sizes by a cascade impactor. The concentrations of heavy metals in atmospheric particles of different sizes, collected from the air and from factories, were measured using an inductively coupled plasma mass spectrometry (ICP-MS). The results indicated that the average concentration of PM, chromium (Cr), arsenic (As), cadmium (Cd) and lead (Pb) in PM was 177.3 ± 33.2 μg/m³, 37.3 ± 8.8 ng/m³, 17.3 ± 8.1 ng/m³, 4.8 ± 3.1 ng/m³ and 141.6 ± 49.1 ng/m³, respectively. The size distribution of PM displayed a bimodal distribution; the maximum PM size distribution was at 1.1-2.1 μm, followed by 9-10 μm. The size distribution of As, Cd and Pb in PM was similar to the distribution of the PM mass, with peaks observed at the range of 1.1-2.1 μm and 9-10 μm ranges while for Cr, only a single-mode at 4.7-5.8 μm was observed. PM (64.7%), As (72.5%), Cd (72.2%) and Pb (75.8%) were associated with the fine mode below 2.1 μm, respectively, while Cr (46.6%) was associated with the coarse mode. The size distribution characteristics, enrichment factor, correlation coefficient values, source information and the analysis of source samples showed that As, Cd and Pb in PM were the typical heavy metal in lead and zinc smelting affected areas, which originated mainly from lead and zinc smelting sources.

The burden of disease attributable to ambient PM2.5-bound PAHs exposure in Nagpur, India

Exposure to PM_2.5-bound polycyclic aromatic hydrocarbons (PAHs) can elicit several types of cancer and non-cancer effects. Previous studies reported substantial burdens of PAH-induced lung cancer, but the burdens of other cancer types and non-cancer effects remain unknown. Thus, we estimate the cancer and non-cancer burden of disease, in disability-adjusted life years (DALYs), attributable to ambient PM_2.5-bound PAHs exposure in Nagpur district, India, using risk-based approach. We measured thirteen PAHs in airborne PM_2.5 sampled from nine sites covering urban, peri-urban and rural areas, from February 2013 to June 2014. We converted PAHs concentrations to benzo[a]pyrene equivalence (B[a]P_eq) for cancer and non-cancer effects using relative potency factors, and relative toxicity factors derived from quantitative structure-activity relationships, respectively. We calculated time-weighted exposure to B[a]P_eq, averaged over 30 years, and adjusted for early-life susceptibility to cancer. We estimated the DALYs/year using B[a]P_eq exposure levels, published toxicity data, and severity of the diseases from Global Burden of Disease 2016 database. The annual average concentration of total PM_2.5-bound PAHs was 458 ± 246 ng/m³ and resulted in 49,500 DALYs/year (0.011 DALYs/person/year). The PAH-related DALYs followed this order: developmental (mostly cardiovascular) impairments (55.1%) > cancer (26.5%) or lung cancer (23.1%) > immunological impairments (18.0%) > reproductive abnormalities (0.4%).

In Vitro and In Vivo Experimental Studies of PM2.5 on Disease Progression

Air pollution is a very critical issue worldwide, particularly in developing countries. Particulate matter (PM) is a type of air pollution that comprises a heterogeneous mixture of different particle sizes and chemical compositions. There are various sources of fine PM (PM2.5), and the components may also have different effects on people. The pathogenesis of PM2.5 in several diseases remains to be clarified. There is a long history of epidemiological research on PM2.5 in several diseases. Numerous studies show that PM2.5 can induce a variety of chronic diseases, such as respiratory system damage, cardiovascular dysfunction, and diabetes mellitus. However, the epidemiological evidence associated with potential mechanisms in the progression of diseases need to be proved precisely through in vitro and in vivo investigations. Suggested mechanisms of PM2.5 that lead to adverse effects and chronic diseases include increasing oxidative stress, inflammatory responses, and genotoxicity. The aim of this review is to provide a brief overview of in vitro and in vivo experimental studies of PM2.5 in the progression of various diseases from the last decade. The summarized research results could provide clear information about the mechanisms and progression of PM2.5-induced disease.

Spatial pattern and variations in the prevalence of congenital heart disease in children aged 4-18 years in the Qinghai-Tibetan Plateau

PURPOSE

This study aimed to investigate the spatial distribution pattern of the prevalence of congenital heart disease (CHD) in children in Qinghai-Tibetan Plateau (QTP), a high-altitude region in China.

METHODS

Epidemiological data from a survey on the prevalence of CHD in Qinghai Province including 288,066 children (4-18 years) were used in this study. The prevalence and distribution pattern of CHD was determined by sex, CHD subtype, and nationality and altitude. Spatial pattern analysis using Getis-Ord Gi^⁎ was used to identify the spatial distribution of CHD. Bayesian spatial binomial regression was performed to examine the relationship between the prevalence of CHD and environmental risk factors in the QTP.

RESULTS

The prevalence of CHD showed a significant spatial clustering pattern. The Tibetan autonomous prefecture of Yushu (average altitude > 4000 m) and the Mongolian autonomous county of Henan (average altitude > 3600 m) in Huangnan had the highest prevalence of CHD. Univariate analysis showed that with ascending altitude, the total prevalence of CHD, that in girls and boys with CHD, and that of the subtypes PDA and ASD increasing accordingly. Thus, environmental factors greatly contributed to the prevalence of CHD.

CONCLUSIONS

The prevalence of CHD shows significant spatial clustering pattern in the QTP. The CHD subtype prevalence clustering pattern has statistical regularity which would provide convenient clues of environmental risk factors. Our results may provide support to make strategies of CHD prevention, to reduce the incidence of CHD in high altitude regions of China.

The gains in life expectancy by ambient PM2.5 pollution reductions in localities in Nigeria

Global burden of disease estimates reveal that people in Nigeria are living shorter lifespan than the regional or global average life expectancy. Ambient air pollution is a top risk factor responsible for the reduced longevity. But, the magnitude of the loss or the gains in longevity accruing from the pollution reductions, which are capable of driving mitigation interventions in Nigeria, remain unknown. Thus, we estimate the loss, and the gains in longevity resulting from ambient PM_2.5 pollution reductions at the local sub-national level using life table approach. Surface average PM_2.5 concentration datasets covering Nigeria with spatial resolution of ∼1 km were obtained from the global gridded concentration fields, and combined with ∼1 km gridded population of the world (GPWv4), and global administrative unit layers (GAUL) for territorial boundaries classification. We estimate the loss or gains in longevity using population-weighted average pollution level and baseline mortality data for cardiopulmonary disease and lung cancer in adults ≥25 years and for respiratory infection in children under 5. As at 2015, there are six "highly polluted", thirty "polluted" and one "moderately polluted" States in Nigeria. People residing in these States lose ∼3.8-4.0, 3.0-3.6 and 2.7 years of life expectancy, respectively, due to the pollution exposure. But, assuming interventions achieve global air quality guideline of 10 μg/m³, longevity would increase by 2.6-2.9, 1.9-2.5 and 1.6 years for people in the State-categories, respectively. The longevity gains are indeed high, but to achieve them, mitigation interventions should target emission sources having the highest population exposures.

Particle-Associated Polycyclic Aromatic Hydrocarbons (PAHs) in the Atmosphere of Hefei, China: Levels, Characterizations and Health Risks

Airborne PM2.5 and PM10 samples were collected in summertime (August 2015) and wintertime (December 2015-January 2016) in an industrial complex area in Hefei, China. The average concentrations of PM2.5 and PM10 (90.5 and 114.5 μg/m³, respectively) were higher than the regulated levels of China National Ambient Air Quality Standard (grade I) and the WHO Ambient (outdoor) Air Quality and Health Guideline Value. Seasonal variations in PM2.5/PM10 indicated that the secondary sources of particulate matters, formed by gas-to-particle conversion, were enhanced in summer due to longer time of solar radiation and higher temperature. The total concentrations of PM2.5- and PM10-associated PAHs were 5.89 and 17.70 ng/m³ in summer as well as 63.41 and 78.26 ng/m³ in winter, respectively. Both PM2.5- and PM10-associated PAHs were dominated by 4- to 6-ring PAHs, suggesting that the fossil fuel combustion and vehicle emissions were the primary sources of PAHs in atmospheric particulate matters in Hefei. The total concentration of PAHs had a slightly higher correlation coefficient with PM2.5 (R = 0.499, P < 0.05) than PM10 (R = 0.431, P > 0.05), indicating the higher association tendency of PAHs with PM2.5. The coefficient of divergence analysis showed that the compositions of PAH were quite different between summer and winter. Total BaP equivalent concentration (BaP-TEQ) for particulate-bound PAHs in winter (58.87 ng/m³) was higher than that in summer (5.53 ng/m³). In addition, particulate-bound PAHs in winter had an inhalation cancer risk (ICR) value of 2.8 × 10^-3, which was higher than the safe range (10^-4-10^-6).

Estimated individual inhaled dose of fine particles and indicators of lung function: A pilot study among Chinese young adults

Fine particle (PM_2.5)-related lung damage has been reported in most studies regarding environmental or personal PM_2.5 concentrations. To assess effects of personal PM_2.5 exposures on lung function, we recruited 20 postgraduate students and estimated the individual doses of inhaled PM_2.5 based on their microenvironmetal PM_2.5 concentrations, time-activity patterns and refereed inhalation rates. During the period of seven consecutive days in each of the four seasons, we repeatedly measured the daily lung function parameters and airway inflammation makers such as fractional exhaled nitric oxide (FeNO) as well as systemic inflammation markers including interleukin-1β on the final day. The high individual dose (median (IQR)) of inhaled PM_2.5 was 957 (948) μg/day. We observed a maximum FeNO increase (9.1% (95%CI: 2.2-15.5)) at lag 0 day, a maximum decrease of maximum voluntary ventilation (11.8% (95% CI: 4.6-19.0)) at lag 5 day and a maximum interleukin-1β increase (103% (95% CI: 47-159)) at lag 2 day for an interquartile range increase in the individual dose of inhaled PM_2.5 during the four seasons. Short-term exposure to PM_2.5 assessed by the individual dose of inhaled PM_2.5 was associated with higher airway and systemic inflammation and reduced lung function. Further studies are needed to understand better underlying mechanisms of lung damage following acute exposure to PM_2.5.

Organic contamination and remediation in the agricultural soils of China: A critical review

Soil pollution is a global problem in both developed and developing countries. Countries with rapidly developing economies such as China are faced with significant soil pollution problems due to accelerated industrialization and urbanization over the last decades. This paper provides an overview of published scientific data on soil pollution across China with particular focus on organic contamination in agricultural soils. Based on the related peer-reviewed papers published since 2000 (n=203), we evaluated the priority organic contaminants across China, revealed their spatial and temporal distributions at the national scale, identified their possible sources and fates in soil, assessed their potential environmental risks, and presented the challenges in current remediation technologies regarding the combined organic pollution of agricultural soils. The primary pollutants in Northeast China were polycyclic aromatic hydrocarbons (PAHs) due to intensive fossil fuel combustion. The concentrations of organochlorine pesticides (OCPs) and phthalic acid esters (PAEs) were higher in North and Central China owing to concentrated agricultural activities. The levels of polychlorinated biphenyls (PCBs) were higher in East and South China primarily because of past industrial operations and improper electronic waste processing. The co-existence of organic contaminants was severe in the Yangtze River Delta, Pearl River Delta, and Beijing-Tianjin-Hebei Region, which are the most populated and industrialized regions in China. Integrated biological-chemical remediation technologies, such as surfactant-enhanced bioremediation, have potential uses in the remediation of soil contaminated by multiple contaminants. This critical review highlighted several future research directions including combined pollution, interfacial interactions, food safety, bioavailability, ecological effects, and integrated remediation methods for combined organic pollution in soil.

Assessing on toxic potency of PM2.5-bound polycyclic aromatic hydrocarbons at a national atmospheric background site in North China

A total of 76PM_2.5 samples collected at Tuoji Island from November 2011 to January 2013 were used to analyze 15 congeners of polycyclic aromatic hydrocarbons (∑₁₅PAHs) and assess their toxic potency. The average ∑₁₅PAHs was 15.34±8.87ngm^-3, ranging from 4.24 to 40.62ngm^-3 over the sampling period. BkF, BbF, Phe and BaP were dominant PAH congeners, contributing together 60.64% of the ∑₁₅PAH concentration. The highest monthly ∑₁₅PAHs concentration was in January 2012, followed by the next January, which was closely four times greater than the lowest level occurred in July 2012. Wheat straw burning was responsible for the high PAH concentrations in June 2012. The averaged BaP toxicity equivalent (TEQ-BaP) concentration was 2.70±1.88ngm^-3 over the sampling period. BaP and DaA were the largest contributors, which contributed 58.5% and 14.7% of totals, respectively. The high TEQ-BaP and TEQ-BaP value per unit of ∑₁₅PAHs concentration (TEQ-BaP(U)) values occurred in the cold season and the low levels presented in the warm period. The heaviest monthly TEQ-BaP was 5.28±2.84ngm^-3, which appeared in January 2012; the lowest value was 0.86±0.33ngm^-3, which occurred in July 2012. The potential source contribution function (PSCF) showed the occurrence of the high health risk associated with PAHs in the middle of Liaoning and the south of Shandong Peninsula.

Atmospheric removal of PM2.5 by man-made Three Northern Regions Shelter Forest in Northern China estimated using satellite retrieved PM2.5 concentration

Atmospheric removal of PM_2.5 by the Three Northern Regions Shelter Forest (TNRSF) - the so called Green Great Wall (GGW) in northern China through dry deposition process was estimated using a bulk big-leaf model and a vegetation collection model. Decadal trend of PM_2.5 dry deposition flux from 1999 to 2010 was calculated from modeled dry deposition velocity and air concentration retrieved from the satellite remote sensing. Dry deposition velocities of PM_2.5 calculated using the two deposition models increased in many places of the TNRSF over the last decade due to increasing vegetation coverage of the TNRSF. Both increasing deposition velocity due to forest expansion and PM_2.5 atmospheric level contributed to the increasing deposition flux of PM_2.5. The highest atmospheric deposition flux of PM_2.5 was found in the Central-north region covering Beijing-Tianjin-Hebei area, followed by the Northwestern and the Northeastern regions of the TNRSF. While greater collection of PM_2.5 by vegetation was identified in the Northeastern region of the TNRSF due to higher forest coverage over this region, the most significant incline of the PM_2.5 atmospheric removal due to vegetation collection was discerned in the Central-north region because of the most rapid increase in the vegetation coverage in this region. A total mass of 2.85×10⁷t PM_2.5 was estimated to be removed from the atmosphere through dry deposition process over the TNRSF from 1999 to 2010. The two deposition models simulated similar magnitude and spatial patterns of PM_2.5 dry deposition fluxes. Our results suggest that the TNRSF plays a moderate role in PM_2.5 uptake, but enhances PM_2.5 atmospheric removal by 30% in 2010 than in 1980.

Particulate matter disrupts human lung endothelial cell barrier integrity via Rho-dependent pathways

Increased exposure to ambient particulate matter (PM) is associated with elevated morbidity and mortality in patients with cardiopulmonary diseases and cancer. We and others have shown that PM induces lung microvascular barrier dysfunction which potentially enhances the systemic toxicity of PM. However, the mechanisms by which PM disrupts vascular endothelial integrity remain incompletely explored. We hypothesize that PM induces endothelial cell (EC) cytoskeleton rearrangement via Rho GTPase-dependent pathways to facilitate vascular hyperpermeability. Fine PM induced time-dependent activation of cytoskeletal machinery with increases in myosin light chain (MLC) phosphorylation and EC barrier disruption measured by transendothelial electrical resistance (TER), events attenuated by the Rho-dependent kinase (ROCK) inhibitor Y-27632 or the reactive oxygen species (ROS) scavenger, N-acetylcysteine (NAC). Both Y-27632 and NAC prevented PM-induced stress fiber formation and phospho-MLC accumulation in human lung ECs. PM promotes rapid accumulation of Rho-GTP. This event is attenuated by NAC or knockdown of RhoA (siRNA). Consistent with ROCK activation, PM induced phosphorylation of myosin light chain phosphatase (MYPT) at Thr850, a post-translational modification known to inhibit phosphatase activity. Furthermore, PM activates the guanine nucleotide exchange factor (GEF) for Rho, p115, with p115 translocation to the cell periphery, in a ROS-dependent manner. Together these results demonstrate that fine PM induces EC cytoskeleton rearrangement via Rho-dependent pathways that are dependent upon the generation of oxidative stress. As the disruption of vascular integrity further contributes to cardiopulmonary physiologic derangements, these findings provide pharmacologic targets for prevention of PM-induced cardiopulmonary toxicity.

The health burden and economic costs averted by ambient PM2.5 pollution reductions in Nagpur, India

National estimates of the health and economic burdens of exposure to ambient fine particulate matter (PM_2.5) in India reveal substantial impacts. This information, often lacking at the local level, can justify and drive mitigation interventions. Here, we assess the health and economic gains resulting from attainment of WHO guidelines for PM_2.5 concentrations - including interim target 2 (IT-2), interim target 3 (IT-3), and the WHO air quality guideline (AQG) - in Nagpur district to inform policy decision making for mitigation. We conducted a detailed assessment of concentrations of PM_2.5 in 9 areas, covering urban, peri-urban and rural environments, from February 2013 to June 2014. We used a combination of hazard and survival analyses based on the life table method to calculate attributed annual number of premature deaths and disability-adjusted life years (DALYs) for five health outcomes linked to PM_2.5 exposure: acute lower respiratory infection for children <5years, ischemic heart disease, chronic obstructive pulmonary disease, stroke and lung cancer in adults ≥25years. We used GBD 2013 data on deaths and DALYs for these diseases. We calculated averted deaths, DALYs and economic loss resulting from planned reductions in average PM_2.5 concentration from current level to IT-2, IT-3 and AQG by the years 2023, 2033 and 2043, respectively. The economic cost for premature mortality was estimated as the product of attributed deaths and value of statistical life for India, while morbidity was assumed to be 10% of the mortality cost. The annual average PM_2.5 concentration in Nagpur district is 34±17μgm^-3 and results in 3.3 (95% confidence interval [CI]: 2.6, 4.2) thousand premature deaths and 91 (95% CI: 68, 116) thousand DALYs in 2013 with economic loss of USD 2.2 (95% CI: 1.7, 2.8) billion in that year. It is estimated that interventions that achieve IT-2, IT-3 and AQG by 2023, 2033 and 2043, would avert, respectively, 15, 30 and 36%, of the attributed health and economic loss in those years, translating into an impressively large health and economic gain. To achieve this, we recommend an exposure-integrated source reduction approach.

Bioavailability and health risk of some potentially toxic elements (Cd, Cu, Pb and Zn) in street dust of Asansol, India

Street dust samples were collected from five different types of land use patterns (busy traffic zone, urban residential area, national highways, industrial area and sensitive area) in a medium sized industrial city Asansol, India. The samples were fractionated into ≤53µm and analyzed for potential toxic elements (PTEs) viz. Zn, Cd, Pb and Cu. The mean total concentration of Zn, Cd, Pb and Cu in the urban street dust samples were 192, 0.75, 110 and 132mgkg^-1 respectively. Chemical speciation was performed for PTEs to evaluate the bio-available fractions. Cu was mostly associated with organic matter phase while Zn, Pb and Cd with residual phase. Mean mobility factor (MF) for heavy metals in Asansol was Zn (54.6%)>Pb (49.1%)>Cu (25.3%)>Cd (22.7%). Geo-chemical indices such as Enrichment Factor (EF), geo-accumulation index (Igeo) and contamination Factor (CF) were in the order of Pb>Cd>Zn>Cu. Cluster analysis was done to understand the similarities among the sites. The risks of all metals was calculated with mobile fraction, which indicated actual risk due to PTEs was less (HI<1).

Spatio-temporal variation in chemical characteristics of PM10 over Indo Gangetic Plain of India

The paper presents the spatio-temporal variation of chemical compositions (organic carbon (OC), elemental carbon (EC), and water-soluble inorganic ionic components (WSIC)) of particulate matter (PM10) over three locations (Delhi, Varanasi, and Kolkata) of Indo Gangetic Plain (IGP) of India for the year 2011. The observational sites are chosen to represent the characteristics of upper (Delhi), middle (Varanasi), and lower (Kolkata) IGP regions as converse to earlier single-station observation. Average mass concentration of PM10 was observed higher in the middle IGP (Varanasi 206.2 ± 77.4 μg m(-3)) as compared to upper IGP (Delhi 202.3 ± 74.3 μg m(-3)) and lower IGP (Kolkata 171.5 ± 38.5 μg m(-3)). Large variation in OC values from 23.57 μg m(-3) (Delhi) to 12.74 μg m(-3) (Kolkata) indicating role of formation of secondary aerosols, whereas EC have not shown much variation with maximum concentration over Delhi (10.07 μg m(-3)) and minimum over Varanasi (7.72 μg m(-3)). As expected, a strong seasonal variation was observed in the mass concentration of PM10 as well as in its chemical composition over the three locations. Principal component analysis (PCA) identifies the contribution of secondary aerosol, biomass burning, fossil fuel combustion, vehicular emission, and sea salt to PM10 mass concentration at the observational sites of IGP, India. Backward trajectory analysis indicated the influence of continental type aerosols being transported from the Bay of Bengal, Pakistan, Afghanistan, Rajasthan, Gujarat, and surrounding areas to IGP region.

The health effects of ambient PM2.5 and potential mechanisms

The impacts of ambient PM2.5 on public health have become great concerns worldwide, especially in the developing countries. Epidemiological and toxicological studies have shown that PM2.5 does not only induce cardiopulmonary disorders and/or impairments, but also contributes to a variety of other adverse health effects, such as driving the initiation and progression of diabetes mellitus and eliciting adverse birth outcomes. Of note, recent findings have demonstrated that PM2.5 may still pose a hazard to public health even at very low levels (far below national standards) of exposure. The proposed underlying mechanisms whereby PM2.5 causes adverse effects to public health include inducing intracellular oxidative stress, mutagenicity/genotoxicity and inflammatory responses. The present review aims to provide an brief overview of new insights into the molecular mechanisms linking ambient PM2.5 exposure and health effects, which were explored with new technologies in recent years.

Source identification, apportionment and toxicity of indoor and outdoor PM2.5 airborne particulates in a region characterised by wood burning

The occurrence of airborne particulate matter has been flagged as "of concern" in several megacities, especially in Asia. Selected Chilean regions have similar problems as wood burning is the major source of heating in homes. This concern has led to mitigation measures restricting the burning of wood at periods when the particulate matter smaller than 2.5 μm (PM2.5) concentrations are predicted to be high. This work investigates the linkage between indoor and outdoor particle concentrations, determines their source through the polyaromatic hydrocarbon (PAH) signature and investigates the efficacy of the current management practice of burning restrictions. The PM2.5 fraction was collected at 12 different properties with coincident indoor and outdoor sampling using a low-volume active sampler for 24 hours. Indoor concentrations of PM2.5 ranged from 6 to 194 μg m(-3) with a mean of 72 μg m(-3) and corresponding outdoor concentrations ranged from 5 to 367 μg m(-3) with a mean of 85 μg m(-3) over the winter periods of 2014 and 2015; the Chilean national permitted maximum in outdoor air is 50 μg m(-3) in 24 hours. Higher concentrations were measured when the outdoor air temperature was lower. The PAHs were analysed on the PM2.5 fraction; the indoor concentrations ranged from 2 to 291 ng m(-3) with a mean of 51 ng m(-3) compared to an outdoor concentration between 3 and 365 ng m(-3) with a mean of 71 ng m(-3). Multivariate statistical analysis of the PAH profiles using principal components analysis (PCA) and polytopic vector analysis (PVA) identified wood burning, static and mobile diesel emissions and kerosene combustion as the major contributors to the particulate matter. When converted to toxicity equivalents (BaP-TEQ), the highest toxicity arising from PAHs in the indoor air was associated with a property that used a "leaky" combined wood stove and heater and also used a wood-fired brazier for local heating. In outdoor air, there was a relationship between the housing density and the BaP-TEQ, such that denser housing had higher BaP-TEQ values. The restrictions in wood burning on selected days may have had a measureable effect on the PM2.5 concentrations in that region but the effects were small and only present for the day of the restriction.

Source apportionment and risk assessment of PM1 bound trace metals collected during foggy and non-foggy episodes at a representative site in the Indo-Gangetic plain

The concentration, spatial distribution and source of 13-PM1 bound trace metals (Fe, Cu, Mn, Cr, Zn, Cd, Ni, K, Mg, Na, Ca, Pb and V) and adverse health effects of 5-PM1 bound trace metals (Mn, Zn, Ni, Cr and Cd) collected during foggy and non-foggy episodes are presented. Twenty-four samples from each period (foggy and non-foggy episodes) were collected from Kanpur, a typical densely populated city and the most polluted representative site in the Indo-Gangetic plain of India, and were analyzed for carcinogenic (Ni, Cr and Cd) and non-carcinogenic metals (Mn and Zn). The average mass concentration of PM1 during foggy and non-foggy episodes was found to be 160.16±37.70 and 132.87±27.97μg/m(3). Source identification via principle component analysis suggested that vehicular emission and anthropogenic, industrial and crustal dust were the dominant sources in this region. During both episodes the decreasing order of hazard quotient (Hq) for adult and children was as Mn>Cr>Cd>Ni>Zn. In a non-foggy episode the hazardous index (Hi) values of these 5 trace metals were found to be ~3.5 times higher than a foggy episode's exposed population, respectively. In a foggy episode, due to the exposure to total carcinogenic trace metals (Ni, Cr and Cd) present in the ambient air, 95% probability total incremental lifetime cancer risks (TIlcR) were ~687 cancer cases and ~402 cancer cases per million in the adult population and children population respectively. These cancer cases were ~1.6 times higher than a non-foggy episode's exposed population.

Annual trends in occurrence of submicron particles in ambient air and health risk posed by particle bound metals

Risk analysis is highly important in toxicology and public health studies. Health risk related to exposure to toxic metals of PM1 was assessed. Concentrations of 13 heavy metals, adsorbed to submicron particulate matter PM1 were experimentally examined but only 12 metals were found at detectable levels inside IIT Kanpur campus in 2008-2009 for all months excluding June and October. A total of 90 samples collected for 8 h sampling time by a single stage round nozzle, grease impaction substrate based impactor type PM1 sampler were analysed by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry). Results showed daily average PM1 concentration is 102.46 ± 35.9 μg/m(3) and metal concentration followed the trend: Ca > Fe > Mg > Zn > Pb > Cu > Cr > Ni > Se > Cd > V > As. Contamination level assessment using geo-accumulation index showed Ca, Fe and Mg exhibited non contamination whereas metals like Cr, Zn, As, Cd, Pb, Se, Ni and Cu exhibited ranges from moderate to extreme contamination. Ingestion is found to be the major exposure pathway for heavy metals. Non-carcinogenic health risk assessment for Pb, Cd and Cr (HI > 1) signified strong chances of adverse impact on children whereas adults are well under safe limit. Cancer Risk for adults and children followed the same decreasing order, Cr(VI)>Cd > Ni > As > Pb. It was found to be higher than permissible limits (10(-6)) for adults and children both.

Hydrocarbons and heavy metals in fine particulates in oil field air: possible impacts on production of natural silk

Analyses of fine particulates (PM2.5) from the upper Assam oil fields of India indicated considerable presence of higher hydrocarbons (C22-C35) and heavy metals, Cd, Co, Cr, Cu, Ni, Pb, and Zn. This has raised serious concern for the sustainability of the exotic Muga (Antheraea assama) silk production, which has been a prime activity of a large number of people living in the area. The Muga worm feeds on the leaves of Machilus bombycina plant, and the impacts of air quality on its survival were further investigated by analyzing the leaves of the plant, the plantation soil, and the Muga cocoons. PM2.5 content in the air was much more during the winter due to near calm conditions and high humidity. Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and gas chromatography-mass spectrometer (GC-MS) analysis of PM2.5 showed the presence of higher alkanes (C22-C35) that could be traced to crude oil. Cr, Ni, and Zn were found in higher concentrations in PM2.5, M. bombycina leaves, and the plantation soil indicating a common origin. The winter has been the best period for production of the silk cocoons, and the unhealthy air during this period is likely to affect the production, which is already reflected in the declining yield of Muga cocoons from the area. SEM and protein analyses of the Muga silk fiber produced in the oil field area have exhibited the deteriorating quality of the silk. This is the first report from India on hydrocarbons and associated metals in PM2.5 collected from an oil field and on their possible effects on production of silk by A. assama.