PM10 Samples Research Articles

PS-C35-1: SPOT URINE SODIUM: CREATININE RATIO: A SIMPLE METHOD TO ESTIMATE SODIUM INTAKE

Objective: High sodium intake is a worldwide problem and contributes to high blood pressure and target organ damage. Measurement of 24-hour urine sodium excretion is gold standard for sodium intake evaluation but it is difficult to practice. In this study, the correlation between spot urine sodium: creatinine ratio from second void (AM), before dinner (PM), before bedtime (HS) and 24-hr samples with 24-hour urine sodium were evaluated. Methods: The participants were recruited from single hospital. Participants with age > 20 years, eGFR > 60 ml/min/1.73 m2 and no history of diuretics use were included. Urine sodium, urine creatinine and urine volume of each sample were measured. Urine sodium (mmol/L): urine creatinine (mg/dL) ratio of AM, PM, HS and 24-hour samples were calculated. Correlations of each ratio with 24 hour urine sodium (mmol/day) were studied by Pearson correlation coefficients. Results: 43 participants were included in this study. Mean age was 46.9 ± 13.6 years. Hypertension was diagnosed in 31 participants (72%). Mean blood pressure was 134 ± 15/81 ± 9 mmHg. Estimated eGFR was 100 ± 16 ml/min/1.73 m2. Mean 24 hour urine sodium was 178 + 92 mmol/day (equivalent to sodium intake 4,094 + 2,116 mg/day). Urine sodium: creatinine ratio of AM, PM, HS and 24-hr samples (correlation coefficient, r, with 24-hour urine sodium excretion) were 1.6 ± 0.8 (r = 0.11, P = 0.49), 1.9 ± 1.1 (r = 0.71, P < 0.001), 1.7 ± 1.1 (r = 0.59, P < 0.001) and 1.8 ± 0.7 (r = 0.77, < 0.001) respectively. Spot urine sodium: creatinine ratio from PM sample cut-off point of 1.2 had sensitivity of 81% and specificity of 73% to determine 24-hr urine sodium of 100 mmol/day. Conclusions: Spot urine sodium: creatinine ratio from PM sample correlates well with 24-hr urine sodium (r = 0.62) and ratio of 1.2 is equivalent to 24-hr urine sodium of 100 mmol/day. Sodium intake of study participants was 178 mmol/day which higher than recommended level.

Comparison of Airborne Bacterial Populations Determined by Passive and Active Air Sampling at puy de Dôme, France

Bioaerosols have impacts on atmospheric processes, as well as ecosystem and human health. Common bioaerosol collection methods include impaction, liquid impingement, filtration, and electrostatic precipitation. These methods are used by active samplers that require an air mover and power, but this requirement can also represent a major constraint in field studies. Alternatively, passive samplers do not require power and can operate for long times. In this study, the Rutgers Electrostatic Passive Sampler (REPS), which captures particles by electrostatic attraction and gravitational settling, was deployed at the summit of puy de Dôme (1465 m a.s.l., France) alongside an active PM10 sampler (~1000 L/min) collecting aerosols on a quartz fiber filter. The diversity of the airborne bacteria captured by both samplers across six weekly sampling periods was examined by 16S rRNA gene amplicon sequencing. The dominant phyla observed by both samplers were similar and included Firmicutes, Proteobacteria, and Actinobacteriota. Overall, 12 to 63% of the total bacterial richness at the genus level was shared between the two samplers, depending upon a paired sample, i.e., sampling week. The PM10 sampler and REPS detected the same dominant genera, including Lysinibacillus and Sphingomonas, although their relative abundances for each paired sampler varied. The observed bacterial richness and diversity, as estimated through Shannon’s and Simpson’s indexes, were significantly greater in REPS samples compared to the PM10 samples. The results suggest that REPS could be used for simple and convenient sampling of bioaerosols, especially in remote areas and other locations with limited power access.

Organophosphate esters (OPEs) in atmospheric particulate matter in different Brazilian regions

Regional sources and meteorological variables influence the levels of OPEs in PM10 samples from Limeira, Catalão, and Novo Hamburgo. The concentrations found pose no non-carcinogenic risk to human health.

PM10 Element Distribution and Environmental-Sanitary Risk Analysis in Two Italian Industrial Cities

In this work, an evaluation of the air of two Italian industrial cities, Turin and Biella, has been performed to identify the main sources affecting its quality and to evaluate its evolution along 15 years. These two cities are placed at the border of the Po valley, one of the most polluted areas of Europe, and the automotive and textile industries have been their main economic sectors. The elemental analysis of the PM10 collected there in 2007 has been performed by ICP-MS and ICP-AES. The results identify the urban activities and the soil/road dust resuspension as the main sources of metals. Biella was overall less polluted in PM10 than Turin, probably because of its smaller size, its smaller traffic volume, and the lower number of industries. However, the limit value imposed by the European legislation for daily average PM10 mass concentration (50 μg m−3) was frequently exceeded in the collected samples: 22% and 50%, respectively for Biella and Turin. The concentration of specific toxic metals regulated by Italian legislation was never higher than the limit value for Cd (4 ng m−3) and Pb (0.5 μg m−3), whereas it was exceeded for Ni (20 ng m−3) in 22% of the samples from Turin and only in the 5% of those from Biella. In the same way, the risk analysis, performed using the target hazard quotient (THQ), calculated for children and adult populations, did not reveal warning values. Only for Cd in children were concerning values found (median THQ = 4.9). Element concentrations showed a seasonal trend, with higher values in November and December due to a combination of stable atmospheric conditions and strengthening of anthropic sources (e.g., combustion for heat generation). Finally, data concerning the amount of Cd, Ni, and Pb in the atmosphere provided by the regional agency for environmental protection (ARPA Piedmont) have been used to follow the evolution of these elements from 2007 to 2021 in the two cities. The data reveal a significant reduction of the concentrations of all considered metals in all the sites (higher than 50%), however maintaining the seasonal variability observed in PM10 samples of 2007, with higher concentrations during the cold months and lower concentrations during the summer.

Influence of High-Pressure Torsion Processing on the Tribological Properties of Aluminum Metal Matrix Composites

The motivation for the current study was to improve the wear and frictional properties of Al, Al-Al2O3, and SiC MMCs through HPT processing. The wear test using a tungsten carbide (WC) ball was carried out for different PM and HPT-processed Al and MMC samples. The effect of the sample processing methods on the wear rate, friction, and wear surface morphology was thoroughly investigated. The high hardness after Al grain refinement and reinforcement fragmentation through the HPT processing of the samples increased the wear resistance by 16-81% over that of the PM samples. The average coefficient values and variation ranges were reduced after HPT processing. The Al and Al MMC processing methods affected the wear mechanism and surface morphologies, as proven by the microscopic observations and analyses of the worn surfaces of the samples and WC balls.

A study on the chemical profile and the derived health effects of heavy-duty machinery aerosol with a focus on the impact of alternative fuels

The combustion of petroleum-based fossil fuels is associated with a high environmental burden. Several alternative fuels, including synthetic fuels (e.g., gas-to-liquid, GTL) and biofuels (e.g., rapeseed methyl ester, RME) have been studied in the last few years. While the advantages for the environment (sustainability of biofuels) are well known, research on the resulting health effects from combustion aerosols of these alternative fuels is still scarce. Consequently, we investigated the chemical combustion profile from three distinct fuel types, including a petroleum-based fossil fuel (B0) and two alternative fuels (GTL, RME) under real exposure conditions. We sampled particulate matter (PM2.5, PM0.25) and the gas phase from heavy-duty machinery and evaluated the general pattern of volatile and semi-volatile organic compounds, elemental and organic carbon as well as a range of transition metals in the size segregated PM and/or gas phase. The use of comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry enabled us to classify distinct methylated PAHs in the PM samples and its high abundance, especially in the fine fraction of PM. We found that (methylated) PAHs were highly abundant in the PM of B0 compared to GTL and RME. Highest concentrations of targeted aromatic species in the gas phase were released from B0. In summary, we demonstrated that GTL and RME combustion released lower amounts of chemical compounds related to adverse health effects, thus, the substitution of petroleum-based fuels could improve air quality for human and the environment.

In vitro assessment of the pulmonary toxicity of particulate matter emitted during haze events in Chiang Mai, Thailand via investigation of macrophage responses

Chiang Mai (Thailand) experiences severe haze pollution in the dry season (December–April) each year mainly due to local and regional biomass burning (e.g. of agricultural land). A major component of the haze is airborne particulate matter (PM). During haze events, biomass burning is likely to be the dominant source of PM emissions, and at other times emissions from traffic dominate. The hazard of traffic derived PM has been extensively investigated previously but there are uncertainties regarding the toxicity of PM emitted from biomass burning. The toxicity of PM10 samples collected during and after haze events in Chiang Mai in 2020 was compared in vitro in J774.1 macrophages as they are responsible for the clearance of inhaled particles. Diesel exhaust particles and ultrafine carbon black were included as benchmark particles as they have been commonly used as a surrogate for PM. Cytotoxicity was evaluated 24 h post exposure at concentrations of 3.9–125 µg ml−1. Cytokine production (tumour necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-1β, macrophage inflammatory protein (MIP-2)) was assessed and cell morphology visualised using light and scanning electron microscopy. The hydrodynamic diameter, zeta potential and endotoxin content of all particles was assessed as well as the metal content of PM samples. All particles induced a concentration dependent decrease in cell viability and increased TNF-α and MIP-2 production. Only PM samples stimulated IL-6 production and only non-haze PM caused IL-1β production. No change in IL-10 production was detected for any particle. PM samples and DEP caused vacuole formation in cells. The concentrations of endotoxin and metals were highest in non-haze PM, which may explain why it induced the greatest inflammatory response. As non-haze PM was more toxic than haze PM, our results indicate that the source of PM emissions can influence its toxic potency and more specifically, that PM emitted from biomass burning may be less toxic than PM emitted from traffic.

Simultaneous Determination of 79 Polar and Non-Polar Polycyclic Aromatic Compounds in Airborne Particulate Matter by Gas Chromatography – Tandem Mass Spectrometry

Research on Polycyclic Aromatic Compounds (PACs) in the atmospheric environment has been mainly focused on the 16 EPA’s PAHs. Due to toxicological relevance and particular emission sources, there is a research need in broadening the scope of PACs analysis to include polar and semi-polar PACs in new analytical methods. Here, we describe a single GC-MS/MS method to simultaneously determine 79 polar, semi-polar and non-polar PACs. Temperature gradient and injection conditions were optimized. Optimal Multiple Reaction Monitoring (MRM) and pseudo-MRM mass transitions were searched to enhance the detection. PACs were extracted from particulate samples by Pressurized Liquid Extraction (PLE). The choice of the optimal extraction solvent was carefully evaluated. Instrumental LOQ were from 1 to 2 ng. The method was validated against linearity of the calibration, intra-day and inter-day variability, LOQ and recoveries. The analysis of a Diesel Particulate Matter Certified Reference Material enabled a firm method validation. The method was applied to PM10 samples from a residential parking lot. PACs total amount varied from 2.3 to 14 ng/m3. The most abundant PACs were phthalic anhydride, 1,8-naphthalic anhydride and benzo(b)fluoranthene. PAHs diagnostic ratios enabled the identification of fuel combustion and vehicular traffic as the main source of PACs.

The Impact of COVID-19 Lockdown Strategies on Oxidative Properties of Ambient PM10 in the Metropolitan Area of Milan, Italy

This research investigates the impact of controlling pandemic measures on the characteristics of atmospheric particulate matter (PM), with specific concern to its toxicity, measured by its oxidative properties. The investigated PM10 samples were collected in the metropolitan area of Milan during the epidemic lockdown, and their oxidative potential (OP) was assessed using ascorbic acid (AA) and dithiothreitol (DTT) acellular assays. During the full lockdown, we estimated reductions to 46% and 60% for nitrogen dioxide (NO2) and black carbon (BC) concentrations, respectively, based on the aggregated 2018–2019 data of NO2 and BC levels, used as baseline conditions. To quantify the impact of lockdown restrictions on PM oxidative activity, we studied the OP data measured in our laboratory on PM10 filters and directly compared the results from 15–30 April 2020 with those from the same time span in 2019. The OPAA values dropped to nearly 50%, similar to the concentration decrease in Elemental Carbon (EC) and traffic related metals, as well as to the variation in NO2 level. Otherwise, the OPDTT responses decreased to nearly 75%, as described by the corresponding reduction in Organic Carbon (OC) concentration and BC level.

Characterization and Formation Mechanism of Water-soluble Inorganic Ions in PM2.5 and PM10 in Summer in the Urban Agglomeration of the Ili River Valley

The simultaneous observation and analysis of atmospheric particles on a regional scale is an important approach to developing control strategies for air pollution. To study the spatial distribution characteristics of particulate matter and water-soluble inorganic ions in the Ili Valley Urban agglomeration, PM2.5 and PM10 samples were synchronously collected from July 19 to July 29, 2021 in Yining City and the surrounding three counties, and then nine types of water-soluble inorganic ions (WSIIs) were analyzed. The spatial distribution characteristics, existence form of WSIIs, and influencing factors were discussed in depth. The results showed that the average ρ(PM2.5) and ρ(PM10) in the Ili River Valley urban agglomeration in summer were 23 μg·m-3 and 59 μg·m-3, respectively. The emission of local industrial and mobile sources in Yining City was higher than that of the surrounding three counties, resulting in the highest ρ(PM2.5) in the region (25 μg·m-3). Due to the influence of dust sources and topography, the ρ(PM10) in Yining county was the highest in the region (63 μg·m-3). Huocheng county is located upwind of the region, and these favorable diffusion conditions resulted in the lowest ρ(PM2.5) and ρ(PM10) (20 μg·m-3 and 49 μg·m-3, respectively). The concentrations of WSIIs in PM2.5 and PM10 ranged from 28.2%-29.9% and 16.0%-20.2%, respectively. The four main ions (SO42-, NO3-, NH4+, and Ca2+) accounted for approximately 90% of WSIIs mass concentrations. The concentration order of the four main ions in PM2.5 was SO42->Ca2+>NH4+>NO3- and SO42->Ca2+>NO3->NH4+ in PM10. The results of correlation analysis showed that the similar SO42- concentrations in the four cities were mainly caused by regional transport. Ca2+ was the highest-concentration ion in PM10 of Yining City and Qapqal Xibe Autonomous county, and the proportion of Ca2+ was significantly higher than that in most cities in China, which reflected that the cities in the core area of the Ili Valley were greatly affected by the dust sources. The ratios of n(NO3-)/n(SO42-) in PM2.5 and PM10 were 0.78 and 0.76, respectively, indicating that the influence of stationary sources was greater than that of mobile sources. The ratio of n(NO3-)/n(SO42-) in Yining City>Huocheng county>Yining county>Qapqal Xibe Autonomous county, which was consistent with the motor vehicle populations of the four cities, reflecting that Yining City was affected by motor vehicle sources more than the surrounding three counties. The secondary components mainly existed in the form of (NH4)2SO4, NH4HSO4, and NH4NO3. There was excess ammonia after the reaction between NH4+ and SO42- in each city. NH4NO3 mainly existed in Yining City, which was mainly related to high NO2 in Yining City. The NOR of the four cities were 0.03-0.10 and 0.03-0.16 in PM2.5 and PM10, respectively, and the secondary transformation of NO3- was weak due to the influence of high temperatures in summer. The SOR were 0.21-0.41 and 0.23-0.44, respectively. The SOR of Qapqal Xibe Autonomous county was the highest due to the relatively high humidity, whereas the SOR of Huocheng county was higher than that of the three sites in Yining City due to the influence of regional transportation. The formation mechanisms showed that SO42- in Qapqal Xibe Autonomous county and Yining City were mainly produced by the heterogeneous reaction, and in Yining county it was mainly formed via the homogeneous reaction. However, the formation mechanism in Huocheng county was complex and was affected by both homogeneous and heterogeneous reactions.

Exhaust and non-exhaust contributions from road transport to PM10 at a Southern European traffic site

It is a well – established fact that road traffic is one of the main contributors to ambient levels of airborne particulate matter (APM). This study was carried out at a traffic site in which the PM10 levels are monitored all year round. A trend analysis of these levels revealed that over a decade there was no discernible trend, with the PM10 concentrations normally hovering around the EU limit values. In 2018, one of these limit values was exceeded. The contribution of traffic at the site was therefore investigated through a chemical speciation of 209 PM10 samples collected throughout this year. The speciation data were used in a source apportionment exercise in which the output of the PMF model was further refined using the lesser–known, constraint weighted non – negative matrix factorization (CW – NMF) model. This technique enabled the isolation of two factors clearly related to traffic, which were labelled as “exhaust contribution” (responsible for 3.4% of the PM10), “tire/brake wear contribution” (contributing 17% of the PM10). Additionally, a factor including both traffic resuspended dust and crustal material was also isolated and labelled “road dust/crustal” factor. The two contributors to the factor jointly contribute 18% to the PM10 and the contribution of the traffic resuspended dust was estimated at 7.3%. The traffic resuspended component of this factor together with the “tire/brake wear contribution” jointly make up the non-exhaust contribution of traffic – derived dust. Consonant with what has been known for quite some time, the exhaust fraction is the minor component of traffic PM10. It is therefore, clear that policies aimed at controlling traffic derived PM10 pollution at the receptor will have a minimal effect unless the non – exhaust emissions are adequately controlled.

Evaluation of Mass Spectrometric Methods for Screening Polycyclic Aromatic Hydrocarbons in the Particulate Phase of Wildfire/Biomass Smoke.

Polycyclic aromatic hydrocarbons (PAHs) are a class of compounds containing multiple aromatic rings formed during incomplete combustion. Since many of them are known mutagens and carcinogens, PAHs found in the particulate matter (PM) from the wildfire smoke may pose significant health risks to the wildland firefighters. It is pivotal to determine the levels of PAHs in the PM to evaluate the health effects of their inhalation exposure. However, the determination of PAHs using the conventional chromatographic approaches is often time-consuming and laborious. Herein, we describe a novel method for screening nonpolar and polar PAHs in the PM of smoke by direct analysis in real-time mass spectrometry (DART-MS). PM2.5 and PM10 samples were collected on the quartz filters with a sampling system consisting of a cascade impactor with a portable sampling pump. Various indoor and outdoor experiments from biomass burns were conducted to evaluate the PM sampling systems. PAHs were analyzed by DART-MS and gas chromatography-mass spectrometry (GC-MS) methods. The PM samples were collected in California during the wildfire season of fall 2020, and significant levels of multiple nonpolar PAHs and polar PAHs were detected. Overall, the DART-MS method has shown promising ability for high-throughput screening of PAHs in the PM of smoke. Further studies are currently under way to apply this method to study the particulate phase PAH exposures of wildland firefighters during their firefighting activities.

Discovering oxidative potential (OP) drivers of atmospheric PM10, PM2.5, and PM1 simultaneously in North-Eastern Spain

Ambient particulate matter (PM) is a major contributor to air pollution, leading to adverse health effects on the human population. It has been suggested that the oxidative potential (OP, as a tracer of oxidative stress) of PM is a possible determinant of its health impact. In this study, samples of PM10, PM2.5, and PM1 were collected roughly every four days from January 2018 until March 2019 at a Barcelona urban background site and Montseny rural background site in northeastern Spain. We determined the chemical composition of samples, allowing us to perform source apportionment using positive matrix factorization. The OP of PM was determined by measuring reactive oxygen species using dithiothreitol and ascorbic acid assays. Finally, to link the sources with the measured OP, both a Pearson's correlation and a multiple linear regression model were applied to the dataset. The results showed that in Barcelona, the OP of PM10 was much higher than those of PM2.5 and PM1, whereas in Montseny results for all PM sizes were in the same range, but significantly lower than in Barcelona. In Barcelona, several anthropogenic sources were the main drivers of OP in PM10 (Combustion + Road Dust + Heavy Oil + OC-rich) and PM2.5 (Road Dust + Combustion). In contrast, PM1 -associated OP was driven by Industry, with a much lower contribution to PM10 and PM2.5 mass. Meanwhile, Montseny exhibited no clear drivers for OP evolution, likely explaining the lack of a significant difference in OP between PM10, PM2.5, and PM1. Overall, this study indicates that size fraction matters for OP, as a function of the environment typology. In an urban context, OP is driven by the PM10 and PM1 size fractions, whereas only the PM1 fraction is involved in rural environments.

Phytoliths in particulate matter released by wind erosion on arable land in La Pampa, Argentina

Silicon (Si) is considered a beneficial element in plant nutrition, but its importance on ecosystems goes far beyond that. Various forms of silicon are found in soils, of which the phytogenic pool plays a decisive role due to its good availability. This Si returns to the soil through the decomposition of plant residues, where they then participate in the further cycle as biogenic amorphous silica (bASi) or so-called phytoliths. These have a high affinity for water, so that the water holding capacity and water availability of soils can be increased even by small amounts of ASi. Agricultural land is a considerable global dust source, and dust samples from arable land have shown in cloud formation experiments a several times higher ice nucleation activity than pure mineral dust. Here, particle sizes in the particulate matter fractions (PM) are important, which can travel long distances and reach high altitudes in the atmosphere. Based on this, the research question was whether phytoliths could be detected in PM samples from wind erosion events, what are the main particle sizes of phytoliths and whether an initial quantification was possible.Measurements of PM concentrations were carried out at a wind erosion measuring field in the province La Pampa, Argentina. PM were sampled during five erosion events with Environmental Dust Monitors (EDM). After counting and classifying all particles with diameters between 0.3 and 32 µm in the EDMs, they are collected on filters. The filters were analyzed by Scanning Electron Microscopy and Energy Dispersive X-Ray analysis (SEM-EDX) to investigate single or ensembles of particles regarding composition and possible origins.The analyses showed up to 8.3 per cent being phytoliths in the emitted dust and up to 25 per cent of organic origin. Particles of organic origin are mostly in the coarse dust fraction, whereas phytoliths are predominately transported in the finer dust fractions. Since phytoliths are both an important source of Si as a plant nutrient and are also involved in soil C fixation, their losses from arable land via dust emissions should be considered and its specific influence on atmospheric processes should be studied in detail in the future.

Compositional characteristics and toxicological responses of human lung epithelial cells to inhalable particles (PM10) from ten typical biomass fuel combustions

As the primary component of haze, atmospheric inhalable particulate matters (PM10) are highly detrimental to human health. Biomass combustion is one of China's most pivotal sources to aerosols pollution, inducing non-negligible emissions and uncertain risks. PM10 samples directly from 10 representative biomass fuel combustion sources (2 groups covering the reality widely: straws of rice, wheat, corn, corncob, soybean, peanut, rape, sesame; and branches of pine, peach) were collected using the dilution channel sampler and analyzed for chemical compositions and in vitro cytotoxicity to human lung epithelial cell lines A549. The components of PM10 are dominated by organic carbon (OC), followed by water-soluble K+ and Cl−, and rich in metals Fe, Zn, Cr, and Ni. Generally, PM10 emitted from biomass fuel combustions can weaken the antioxidant capacity of cells, and straws emissions, especially rape and peanut straws, show stronger ability to further induce oxidative stress and inflammatory damage than fuelwoods, owing to the key toxic roles of Cr, Ni, and Co. Therefore, reducing the specific source emissions of PM10 from crop straw combustions rich in heavy metals could be an effective oriented strategy to improve environmental air quality and control aerosols pollution precisely for protecting public health.

Graduation Towers Impact on the Concentration and Chemical Composition of Ambient Aerosol: A Case Study from Wieliczka Salt Mine in Poland

The aim of the research was to determine the effect of graduation towers on the aerosol concentration and its composition not only in the vicinity of the graduation tower itself, but also at a distance from it, on the example of the brine graduation tower in the Wieliczka Salt Mine health resort. Two measurement sites were selected for the research, one located inside the graduation tower and the other at the guard booth—at a considerable distance from the graduation tower. Total suspended particulate (TSP) and PM10 (particulate matter with a diameter that does not exceed 10 µm) samples were taken simultaneously using the aspiration method. The collected samples were subjected to analyses of TSP and PM10 concentrations, the content of organic carbon (OC), elemental carbon (EC) and selected ions. It was confirmed that the composition of the aerosol in the Wieliczka Salt Mine significantly differs from the typical aerosol composition in inland locations and is similar to the aerosol composition in coastal zones. The comparison of the aerosol composition at both measuring sites clearly indicates a very favorable influence of the brine graduation tower on the composition of the atmospheric aerosol, even at a certain distance from it.

Diagnostic thresholds and optimal collection protocol of salivary pepsin for gastroesophageal reflux disease.

Gastroesophageal reflux disease (GERD) is primarily diagnosed based on symptoms and response to a proton-pump inhibitor (PPI) trial. Gold standard testing requires an invasive endoscopic procedure, often with ambulatory pH monitoring. Salivary pepsin is a potential noninvasive modality for GERD diagnosis. This study aimed to assess diagnostic performance of salivary pepsin thresholds for GERD and determine optimal collection protocol of saliva in an external validation cohort. Over 10months, adults with symptoms of GERD undergoing esophagogastroduodenoscopy with wireless pH-monitoring off PPI were enrolled. Saliva was self-collected by participants over 4 days across three different time points: fasting ante meridiem (AM), post-prandial, and bedtime (PM). Pepsin levels were calculated via Peptest. Pepsin variability and agreement were determined using linear mixed effects models and intraclass correlation. Validation of diagnostic threshold and performance characteristics were evaluated by receiver-operator curve analysis. Twenty participants enrolled in the study; 50% with physiologic acid exposure (acid exposure time < 4% no GERD) and 50% with elevated acid exposure (GERD). Mean pepsin concentrations were significantly lower in the AM (22.6 ± 25.2ng/mL) compared to post-prandial (44.5 ± 36.7ng/mL) and PM (55.4 ± 47.0ng/mL). Agreement between pepsin concentrations across 3 days was substantial for AM samples (kappa 0.61), with lower agreement for post-prandial and PM samples. A single AM pepsin concentration of 25ng/mL was 67% accurate for GERD with 56% sensitivity and 78% specificity. This validation study highlights fair accuracy and performance characteristics of a single fasting AM salivary pepsin concentration for the diagnosis of GERD.

Examination of effect modification of the relationship between PM2.5 and cardiovascular mortality by particle oxidative potential within two Canadian cities

BACKGROUND AND AIM There is evidence that particle oxidative potential modifies effects of fine particulate matter air pollution (PM2.5) on health outcomes in between-cities studies in Canada. Additionally, previous work shows that oxidative potential of PM2.5 varies considerably at the within-city spatial scale. The aim of the present study was to determine if differences in the oxidative potential of PM2.5 at the within-city spatial scale modify the relationship between PM2.5 and cardiovascular mortality. METHODS We conducted a cohort study in the Canadian Census Health and Environment Cohort, a population-based cohort based on the Canadian longform Census. We followed participants who lived in the cities of Toronto or Montreal, Canada, at least 2 years in the period 2001-2016 (approximately 12 271 100 person-years in 1 101 000 individuals, rounded for confidentiality). Annual estimates of PM2.5 exposures were assigned from satellite data calibrated with ground-based observations, and oxidative potential was measured on samples of PM2.5 taken at 234 sites across the study area. We used time-varying Cox proportional hazards models to estimate hazard ratios for the effect of PM2.5 on cardiovascular mortality within strata of PM2.5 oxidative potential. Additionally, we estimated hazard ratios for oxidative burden (the product of oxidative potential and PM2.5 exposures). RESULTS We did not find evidence that oxidative potential modifies the effect of PM2.5 on mortality from cardiovascular causes (N = approximately 6100 events). The overall relationship between PM2.5 exposures and cardiovascular mortality was not significantly different from the null, and the same was true for oxidative burden measures. CONCLUSIONS Spatial variability in PM2.5 and the oxidative potential of PM2.5 may be insufficient for OP to act as a modifier of the effect of PM2.5 on cardiovascular mortality within the cities of Toronto and Montreal. KEYWORDS : fine particulate matter, oxidative potential, outdoor air pollution, cardiovascular disease

Size fraction of hazardous particulate matter governing the respiratory deposition and inhalation risk in the highly polluted city Delhi.

Delhi has been identified as one of the highly polluted cities in the world and recently associated with the highest population weighted PM2.5 concentration. However, the unavailability of the health risk estimations using long-term data for Indian cities has been pointed out as a hurdle in performing the correct assessment. The present work estimated deposition of particles in different regions of respiratory systems (head airway = 67% deposition for 2.5µm particles; tracheo-bronchiolar (TB) = 73% deposition for 1.0µm particles; alveolar (AL) = 17% deposition for 0.5µm, 0.25µm, and < 0.25µm particles) using PM samples collected at a breathing height of 1.5m near the major ring road in New Delhi (India). The calculated risk index (RI) varied considerably between winter (1.21 ± 0.26 to 1.33 ± 0.50) and pre-monsoon-southwest monsoon months (0.34 ± 0.08 to 0.96 ± 0.27). Respiratory deposition dose of nanosized particles (≤ 500nm) in the alveoli region of the lung was found to be considerable (35%) indicating the need for understanding the role of these particles in posing health risk. Although the calculated values of risk metric for exposures of PM-associated metals indicated no risk to IIT Delhi population (hazard quotient < 1 and excess risk of getting cancer < 10-6-10-9), continuous monitoring for particles of different sizes at inhalation height are required for protecting human health.

Proteolysis and lipolysis in Tulum cheeses ripened in plastic barrels and goat skin bags made using Penicillium roqueforti 41 strain

In this research, Tulum cheeses were manufactured from raw (R, RM, RT, and RMT samples) and pasteurized Akkaraman sheep milk cheeses (P and PM samples). Tulum cheeses were manufactured with Penicillium roqueforti 41 strain (RM, PM, RMT samples) and without mold strains (R, P, and RT samples). The cheeses were ripened in plastic barrels (R, RM, P, and PM samples) or goat skin bags (called tulum) (RT and RMT samples) for 120 days at + 4 °C. In the last two stages of the ripening period (60 d =90th and 90 d=120th), samples in plastic barrels and tulums were pierced using a needle to allow air entrance. Namely, in the last two stages of the ripening period, all cheese samples were drilled. The cheese was named 60 d = 90th day, which means that it was analyzed on the 90th day after the drilling (piercing) process on the 60th day, and 90 d = 120th day, which means that it was analyzed on the 120th day after the drilling process on the 90th day. The physical, chemical composition, lipolysis, and proteolysis levels of the RT and RMT samples were found to be higher than those of the R, RM, P, and PM samples. The inoculated mold strain (P. roqueforti 41) enhanced the proteolysis and lipolysis levels of the RM, PM, and RMT samples, especially after the piercing operation. Additionally, the inoculated P. roqueforti 41 strain increased the hydrolysis of hydrophobic peptides of RM, PM, and RMT samples depending on mold growth on the 60 d = 90th and 90 d = 120th days of ripening, in which a piercing operation was applied.