Beyond PM2.5: The role of ultrafine particles on adverse health effects of air pollution

Chemical and magnetic analyses on tree bark as an effective tool for biomonitoring: A case study in Lisbon (Portugal)

Tree bark has proven to be a reliable tool for biomonitoring deposition of metals from the atmosphere. The aim of the present study was to test if bark magnetic properties can be used as a proxy of the overall metal loads of a tree bark, meaning that this approach can be used to discriminate different effects of pollution on different types of urban site. In this study, the concentrations of As, Cd, Co, Cu, Fe, Mn, Ni, P, Pb, V and Zn were measured by ICP-OES in bark samples of Jacaranda mimosifolia, collected along roads and in urban green spaces in the city of Lisbon (Portugal). Magnetic analyses were also performed on the same bark samples, measuring Isothermal Remanent Magnetization (IRM), Saturation Isothermal Remanent Magnetization (SIRM) and Magnetic Susceptibility (χ). The results confirmed that magnetic analyses can be used as a proxy of the overall load of trace elements in tree bark, and could be used to distinguish different types of urban sites regarding atmospheric pollution. Together with trace element analyses, magnetic analyses could thus be used as a tool to provide high-resolution data on urban air quality and to follow up the success of mitigation actions aiming at decreasing the pollutant load in urban environments.

Exposure to nanoscale and microscale particulate air pollution prior to mining development near a northern indigenous community in Québec, Canada

This study serves as a baseline characterization of indoor and outdoor air quality in a remote northern indigenous community prior to the start of a major nearby mining operation, including measurements of nanoparticles, which has never been performed in this context before. We performed aerosol sample collection and real-time aerosol measurements at six different locations at the Cree First Nation of Waswanipi and the Montviel campsite, located 45 km west of the Cree First Nation of Waswanipi, in the south of the Nord-du-Québec region. High concentrations of airborne nanoparticles (up to 3.98 × 10⁴ ± 8.9 × 10³ cm^-3 at 64.9-nm midpoint particle diameter) and fine particles (up to 1.99 × 10³ ± 1.6 × 10² cm^-3 at 0.3-μm midpoint particle diameter) were measured inside a residential home, where we did not find any ventilation or air filtration systems. The most abundant particle sizes by mass were between 0.19 and 0.55 μm. The maximum concentration of analyzed heavy metals was detected at the d₅₀ cut-off particle size of 0.31 μm; and the most abundant heavy metals in the aerosol samples were Al, Ba, Zn, Cu, Hg, and Pb. We concluded that the sources of the relatively high indoor particle concentrations were likely laundry machines and cooking emissions in the absence of a sufficient ventilation system. However, the chemical composition of particles resulting from mining activities is expected to be different from that of the aerosol particles from indoor sources. Installation and proper maintenance of sufficient ventilation and air filtration systems may reduce the total burden of disease from outdoor and indoor air pollution and remediate infiltrated indoor particulate pollution from the mining sources as well.

Influence of airborne particulates on respiratory tract deposition of inhaled toluene and naphthalene in the rat

OBJECTIVE

Most studies report that inhaled volatile and semivolatile organic compounds (VOCs/SVOCs) tend to deposit in the upper respiratory tract, while ultrafine (or near ultrafine) particulate matter (PM) (∼100 nm) reaches the lower airways. The objective of this study was to determine whether carbon particle co-exposure carries VOCs/SVOCs deeper into the lungs where they are deposited.

MATERIALS AND METHODS

Male Sprague-Dawley rats were exposed by inhalation (nose-only) to radiolabeled toluene (20 ppm) or naphthalene (20 ppm) on a single occasion for 1 h, with or without concurrent carbon particle exposure (∼5 mg/m³). The distribution of radiolabel deposited within the respiratory tract of each animal was determined after sacrifice. The extent of adsorption of toluene and naphthalene to airborne carbon particles under the exposure conditions of the study was also assessed.

RESULTS

We found that in the absence of particles, the highest deposition of both naphthalene and toluene was observed in the upper respiratory tract. Co-exposure with carbon particles tended to increase naphthalene deposition slightly throughout the respiratory tract, whereas slight decreases in toluene deposition were observed. Few differences were statistically significant. Naphthalene showed greater adsorption to the particles compared to toluene, but overall the particle-adsorbed concentration of each of these compounds was a small fraction of the total inspired concentration.

CONCLUSIONS

These studies imply that at the concentrations used for the exposures in this study, inhaled carbon particles do not substantially alter the deposition of naphthalene and toluene within the respiratory tract.

Indoor particulate pollution in fitness centres with emphasis on ultrafine particles

Fitness centres (FC) represent a unique indoor microenvironment. Exercising on regular basis provides countless health benefits and improves overall well-being, but if these facilities have poor indoor air quality, the respective exercisers might be subjected to some adverse risks. Considering the limited existent data, this work aimed to evaluate particulate pollution (PM_10, PM_2.5, and ultrafine particles - UFP) in indoor air of FC and to estimate the respective risks for occupants (both staff and exercising subjects). Sampling was conducted during 40 consecutive days of May-June 2014 in general fitness areas, studios and classrooms (for group activities) of four different fitness centres (FC1-FC4) situated within Oporto metropolitan area, Portugal. The results showed that across the four FC, PM₁₀ ranged between 5 and 1080 μg m^-3 with median concentrations (15-43 μg m^-3) fulfilling the limit (50 μg m^-3) of Portuguese legislation in all FC. PM_2.5 (medians 5-37 μg m^-3; range 5-777 μg m^-3) exceeded thresholds of 25 μg m^-3 at some FC, indicating potential risks for the respective occupants; naturally ventilated FC exhibited significantly higher PM ranges (p < 0.05). Similarly, UFPs (range 0.5-88.6 × 10³ # cm^-3) median concentrations were higher (2-3 times) at FC without controlled ventilation systems. UFP were approximately twice higher (p < 0.05) during the occupied periods (mean of 9.7 × 10³vs. 4.8 × 10³ # cm^-3) with larger temporal variations of UFP levels observed in general fitness areas than in classrooms and studios. Cardio activities (conducted in studios and classrooms) led to approximately twice the UFPs intakes than other types of exercising. These results indicate that even short-term physical activity (or more specifically its intensity) might strongly influence the daily inhalation dose. Finally, women exhibited 1.2 times higher UFPs intake than men thus suggesting the need for future gender-specific studies assessing UFP exposure.

Real Time Cascade Impactor Based On Surface Acoustic Wave Delay Lines for PM10 and PM2.5 Mass Concentration Measurement

In this research, Surface Acoustic Wave (SAW) sensors are combined with a cascade impactor to perform real time PM10 and PM2.5 mass concentration measurements. The SAW sensors consist of 125 MHz delay lines based on Love waves propagating on an AT-cut quartz substrate. The Love waves are guided on the substrate's surface using a silica layer. SAW sensors themselves are not capable to discriminate particles by their size, therefore, particle separation based on aerodynamic diameter is achieved using a 3 Lpm dedicated cascade impactor. The latter was designed to integrate the SAW sensors which are monitored using a phase shift measurement. The collected particles impact on the acoustic sensor's surface inducing a gravimetric effect that modifies the acoustic wave propagation conditions. The resulted phase shift allows the measurement of the mass deposited on the sensitive zone. The novel cascade impactor with SAW sensors as particle collecting stages is exposed to different aerosols in the 0-150 μg/m³ concentration range and proved to be able to detect and differentiate particles based on their size in real time. The system's response was compared to a commercial optical counter based on light scattering technology and was found to be in good agreement with it.

Systematic Review and Meta-Analysis of Human Skin Diseases Due to Particulate Matter

This study investigated the effects of particulate matter (PM) on human skin diseases by conducting a systematic review of existing literature and performing a meta-analysis. It considered articles reporting an original effect of PM on human skin. From among 918 articles identified, 13 articles were included for further consideration after manual screening of the articles resulted in the exclusion of articles that did not contain data, review articles, editorials, and also articles in languages other than English. Random-effects models and forest plots were used to estimate the effect of PM on the skin by Meta-Disc analysis. According to people's reports of exposure and negative skin effects (atopic dermatitis (AD), eczema, and skin aging, etc.) due to air pollution, the summary relative risk (odds ratio) of PM₁₀ was determined to be 0.99 (95% confidence interval (CI) 0.89-1.11) whereas PM_2.5 was determined to be 1.04 (95% CI 0.96-1.12). Simultaneously, there was a different extent of impact between PM₁₀ and PM_2.5 on atopic dermatitis (AD) for those of young age: the odds ratio of PM₁₀ and PM_2.5 were 0.96 (95% CI 0.83-1.11; I² = 62.7%) and 1.05 (95% CI 0.95-1.16; I² = 46%), respectively. Furthermore, the results suggest an estimated increase of disease incidence per 10 μg/m³ PM of 1.01% (0.08-2.05) due to PM₁₀ and 1.60% (0.45-2.82) due to PM_2.5. Following the results, PM₁₀ and PM_2.5 are associated with increased risks of human skin diseases, especially AD, whose risk is higher in infants and school children. With its smaller size and a high concentration of metals, PM_2.5 is more closely related to AD in younger people, compared to PM₁₀.

The chemical composition of ultrafine particles and associated biological effects at an alpine town impacted by wood burning

This work is part of the TOBICUP (TOxicity of BIomass Combustion generated Ultrafine Particles) project which aimed at providing the composition of ultrafine particles (UFPs, i.e. particles with aerodynamic diameter, d_ae, lower than 100nm) emitted by wood combustion and elucidating the related toxicity. Results here reported are from two ambient monitoring campaigns carried out at an alpine town in Northern Italy, where wood burning is largely diffused for domestic heating in winter. Wintertime and summertime UFP samples were analyzed to assess their chemical composition (i.e. elements, ions, total carbon, anhydrosugars, and polycyclic aromatic hydrocarbons) and biological activity. The induction of the pro-inflammatory cytokine interleukin-8 (IL-8) by UFPs was investigated in two human cells lines (A549 and THP-1) and in human peripheral blood leukocytes. In addition, UFP-induced oxidative stress and genotoxicity were investigated in A549 cells. Ambient UFP-related effects were compared to those induced by traffic-emitted particles (DEP) taken from the NIES reference material "vehicle exhaust particulates". Ambient air UFPs induced a dose-related IL-8 release in both A549 and THP-1 cells; the effect was more relevant on summer samples and in general THP-1 cells were more sensitive than A549 cells. On a weight basis our data did not support a higher biological activity of ambient UFPs compared to DEP. The production of IL-8 in the whole blood assay indicated that UFPs reached systemic circulation and activated blood leukocytes. Comet assay and γ-H2AX evaluation showed a significant DNA damage especially in winter UFPs samples compared to control samples. Our study showed that ambient UFPs can evoke a pulmonary inflammatory response by inducing a dose-related IL-8 production and DNA damage, with different responses to UFP samples collected in the summer and winter periods.

Transcriptomic analyses of human bronchial epithelial cells BEAS-2B exposed to atmospheric fine particulate matter PM2.5

Respiratory exposure is the major route of atmospheric PM_2.5 entering the human body. Epidemiological studies have indicated that exposure to PM_2.5 is associated with increased risk of pulmonary diseases, but the underlying mechanisms remain less clear. In this study, human bronchial epithelial cells (BEAS-2B) were used to investigate the toxic effect and gene expression changes induced by PM_2.5 collected from Beijing, China, based on microarray and following bioinformatic analyses. Gene ontology (GO) analysis indicated that PM_2.5 caused significant changes in gene expression patterns related to a series of important functions, covering gene transcription, signal transduction, cell proliferation, cellular metabolic processes, immune response, etc. Additionally, pathway analysis and signal-net analysis showed that PI3K/Akt, MAPK, and TNF signaling pathways were the most prominently significant pathways affected by PM_2.5, which play key roles in regulating cell proliferation, cell differentiation, cytoskeleton regulation, and inflammatory response. Finally, for the purpose of verifing the accuracy of microarray analysis, qRT-PCR was used to detect the expression of part key genes in the above signaling pathways, which were selected from the signal-net. Our study provided a large amount of information on the molecular mechanism that underling PM_2.5 caused pulmonary diseases, and follow-up researches are still needed for further exploration.

Exposure to air pollutants during commuting in London: Are there inequalities among different socio-economic groups?

People with low income often experience higher exposures to air pollutants. We compared the exposure to particulate matter (PM₁, PM_2.5 and PM₁₀), Black Carbon (BC) and ultrafine particles (PNCs; 0.02-1μm) for typical commutes by car, bus and underground from 4 London areas with different levels of income deprivation (G₁ to G₄, from most to least deprived). The highest BC and PM concentrations were found in G₁ while the highest PNC in G₃. Lowest concentrations for all pollutants were observed in G₂. We found no systematic relationship between income deprivation and pollutant concentrations, suggesting that differences between transport modes are a stronger influence. The underground showed the highest PM concentrations, followed by buses and a much lower concentrations in cars. BC concentrations in the underground were overestimated due to Fe interference. BC concentrations were also higher in buses than cars because of a lower infiltration of outside pollutants into the car cabin. PNCs were highest in buses, closely followed by cars, but lowest in underground due to the absence of combustion sources. Concentration in the road modes (car and bus) were governed by the traffic conditions (such as traffic flow interruptions) at the specific road section. Exposures were reduced in trains with non-openable windows compared to those with openable windows. People from less income-deprived areas have a predominant use of car, receiving the lowest doses (RDD<1μgh^-1) during commute but generating the largest emissions per commuter. Conversely, commuters from high income-deprived areas have a major reliance on the bus, receiving higher exposures (RDD between 1.52 and 3.49μgh^-1) while generating less emission per person. These findings suggest an aspect of environmental injustice and a need to incorporate the socioeconomic dimension in life-course exposure assessments.

Pedestrians in Traffic Environments: Ultrafine Particle Respiratory Doses

Particulate matter has recently received more attention than other pollutants. PM10 and PM2.5 have been primarily monitored, whereas scientists are focusing their studies on finer granulometric sizes due both to their high number concentration and their high penetration efficiency into the respiratory system. The purpose of this study is to investigate the population exposure to UltraFine Particles (UFP, submicrons in general) in outdoor environments. The particle number doses deposited into the respiratory system have been compared between healthy individuals and persons affected by Chronic Obstructive Pulmonary Disease (COPD). Measurements were performed by means of Dust Track and Nanoscan analyzers. Forty minute walking trails through areas with different traffic densities in downtown Rome have been considered. Furthermore, particle respiratory doses have been estimated for persons waiting at a bus stop, near a traffic light, or along a high-traffic road, as currently occurs in a big city. Large differences have been observed between workdays and weekdays: on workdays, UFP number concentrations are much higher due to the strong contribution of vehicular exhausts. COPD-affected individuals receive greater doses than healthy individuals due to their higher respiratory rate.