Chemical characterization of size-segregated PM from different public transport modes and implications of source specific contribution to public exposure

Assessment of air quality in the Philadelphia, Pennsylvania subway

BACKGROUND

Subways are popular and efficient modes of transportation in cities. However, people are exposed to high levels of particulate matter (PM) in subways. Subway air quality in the United States has been investigated in a few cities, but data is lacking on simultaneous measurement of several pollutants, especially ultrafine particles (UFP) and black carbon (BC), in combination with different size fractions of PM.

OBJECTIVES

The goals of this study are to assess air quality in a belowground subway and compare it with outdoor ambient levels, to examine temporal variability of PM in the subway, and to analyze the correlation between PM and BC.

METHODS

Particulate matter of varying sizes (PM1, PM2.5, PM10), UFP, and BC were measured using DustTrak, nanoparticle detector, and micro aethalometer, respectively. Measurements were made at the belowground subway platform and the aboveground street level at 15th Street subway station in Philadelphia during summer 2022.

RESULTS

Belowground mean PM1, PM2.5, and PM10 were 112.2 ± 61.3 µg/m3, 120 ± 65.5 µg/m3, and 182.1 ± 132 µg/m3, respectively, which were 5.4, 5.7, and 7.6 times higher than the respective aboveground street levels. The UFP lung deposited surface area (LDSA) (59.4 ± 36.2 µm2/cm3) and BC (9.5 ± 5.4 μg/m3) belowground were 1.7 times and 10.7 times higher than the aboveground. The pollutant concentration varied from day-to-day on both the locations. A higher positive correlation was found between the belowground BC and PM2.5 (r = 0.51, p < 0.05) compared to the aboveground (r = 0.16, p < 0.05).

IMPACT

This study showed high levels of particulate matter exposure at a belowground subway station in Philadelphia. Particulate matter levels were about 5 to 8 times higher at belowground subway station than the corresponding aboveground street level. Higher levels were also observed for UFP lung deposited surface area (LDSA), while black carbon levels showed the highest concentration at the belowground level by a factor of ten compared to the aboveground level. The study shows the need for air quality management at belowground subways to reduce particulate matter exposure for the commuters.

PM10 promotes an inflammatory cytokine response that may impact SARS-CoV-2 replication in vitro

Introduction

In the last decades, a decrease in air quality has been observed, mainly associated with anthropogenic activities. Air pollutants, including particulate matter (PM), have been associated with adverse effects on human health, such as exacerbation of respiratory diseases and infections. High levels of PM in the air have recently been associated with increased morbidity and mortality of COVID-19 in some regions of the world.

Objective

To evaluate the effect of coarse particulate matter (PM10) on the inflammatory response and viral replication triggered by SARS-CoV-2 using in vitro models.

Methods

Peripheral blood mononuclear cells (PBMC) from healthy donors were treated with PM10 and subsequently exposed to SARS-CoV-2 (D614G strain, MOI 0.1). The production of pro-inflammatory cytokines and antiviral factors was quantified by qPCR and ELISA. In addition, using the A549 cell line, previously exposed to PM, the viral replication was evaluated by qPCR and plaque assay.

Results

SARS-CoV-2 stimulation increased the production of pro-inflammatory cytokines in PBMC, such as IL-1β, IL-6 and IL-8, but not antiviral factors. Likewise, PM10 induced significant production of IL-6 in PBMCs stimulated with SARS-CoV-2 and decreased the expression of OAS and PKR. Additionally, PM10 induces the release of IL-1β in PBMC exposed to SARS-CoV-2 as well as in a co-culture of epithelial cells and PBMCs. Finally, increased viral replication of SARS-CoV-2 was shown in response to PM10.

Conclusion

Exposure to coarse particulate matter increases the production of pro-inflammatory cytokines, such as IL-1β and IL-6, and may alter the expression of antiviral factors, which are relevant for the immune response to SARS-CoV-2. These results suggest that pre-exposure to air particulate matter could have a modest role in the higher production of cytokines and viral replication during COVID-19, which eventually could contribute to severe clinical outcomes.

Evaluation of the selection of proper metro and tram vehicle for urban transportation by using a novel integrated MCDM approach

This paper presents a novel integrated multi-criteria decision-making model consists of the CRITIC (CRiteria Importance Through Intercriteria Correlation) technique and the EDAS (The Evaluation based on Distance from Average Solution) method to evaluate the selection of the urban rail vehicles operated in the public transport systems. In order to determine the selection criteria in a more realistic perspective, a board of experts consists of seven members, who perform as senior executives in the public transport institutions of the country, was constructed and many round tables meetings were organized with together the members of the board for determining the procedure to follow to reach meaningful and applicable results. At the beginning of the research, approximately fifty selection criteria were determined by the research team and some of them were eliminated during the preparation process of this study. Finally, 22 factors were determined as the selection criteria, which will be used in this research. These factors are the selection criteria directly or indirectly affecting the selection process and results. Also, rail tram types currently operated in the various cities of Turkey were determined as decision alternatives. These options were evaluated by using the proposed integrated MCDM approach. When the obtained results are evaluated, it can be seen that the proposed model has the potential to give very successful results for evaluating the selection process of the urban rail systems. Moreover, it can be implemented as a decision support system by decision-makers, who perform in the public transport authorities. Finally, it can also be applied for decision-making problems faced in the various fields.

Oxidative Stress From Exposure to the Underground Space Environment

There are a growing number of people entering underground spaces. However, underground spaces have unique environmental characteristics, and little is known about their effects on human health. It is crucial to elucidate the effects of the underground space environment on the health of humans and other organisms. This paper reviews the effects of hypoxia, toxic atmospheric particles, and low background radiation in the underground space environment on living organisms from the perspective of oxidative stress. Most studies have revealed that living organisms maintained in underground space environments exhibit obvious oxidative stress, which manifests as changes in oxidants, antioxidant enzyme activity, genetic damage, and even disease status. However, there are few relevant studies, and the pathophysiological mechanisms have not been fully elucidated. There remains an urgent need to focus on the biological effects of other underground environmental factors on humans and other organisms as well as the underlying mechanisms. In addition, based on biological research, exploring means to protect humans and living organisms in underground environments is also essential.

Source Apportionment of Coarse Particulate Matter (PM10) in Yangon, Myanmar

The Republic of the Union of Myanmar is one of many developing countries facing concerns about particulate matter (PM). Previously, a preliminary study of PM_2.5 in 2018 suggested that the main source of PM in Yangon, the former capital, was vehicle emissions. However, this suggestion was not supported by any chemical composition data. In this study, to fill that gap, we quantitatively determined source contributions to coarse particulate matter (PM₁₀) in Yangon, Myanmar. PM₁₀ samples were collected in Yangon from May 2017 to April 2018 and chemically analyzed to determine composition. Chemical composition data for these samples were then used in the Chemical Mass Balance (CMB) model to identify the major sources of particulate matter in this area. The results indicate that PM₁₀ composition varies seasonally according to both meteorological factors (e.g., precipitation and temperature) and human activities (e.g., firewood and yard waste burning). The major sources of PM in Yangon annually were dust, secondary inorganic aerosols (SIA), and secondary organic aerosols (SOA), while contributions from biomass burning were more important during the winter months.

Comparative analysis of urban road dust compositions in relation to their potential human health impacts

This study investigated the chemical components of fine urban road dust from seven sampling sites, based on which we could predict potential human health effects. The elemental compositions, including the contents of metals and volatile or semivolatile organic compounds, were determined to establish comprehensive chemical profiles of solid road dust. The chemical profiles, consisting of C: H ratio, metal contents, and relative abundances of organic compounds, provided a chemical signature for road dust. To overall cytotoxicity values ranging between 7 and 58%, water extracts contributed less than 15%, and cell death mainly occurred via direct contact with solid-phase components, which possibly indicates that the selected chemical profile of solid-phase road dust components could serve as a strong predictor for BJ and WI-38 cytotoxicity. Pure metal oxides (Cr₂O₃, CuO, Fe₂O₃, MnO₂, NiO, or ZnO) exhibited a positive dose-response, and the corresponding metal contents in solid road dust were well correlated with cell viability. The principal component analysis (PCA) results suggested that the metal contents were stronger predictors of cytotoxicity than the benzene derivative or hydrocarbon contents. The chemical profiles established in this study could be further utilized to identify candidate health hazard factors in road dust.