Lower Particulate Matter Concentrations Research Articles

Investigating the patterns of air pollution exposure on major cardiovascular events by cluster analysis. Insights from the EP-PARTICLES study on a Polish smog cohort

Abstract Introduction Exposure to air pollution (AP) is a modifiable risk factor for cardiovascular diseases. Aim To analyse the short-term effects of AP on the occurrence of acute coronary syndromes (ACS). Methods The EP-PARTICLES study consists of a retrospective nationwide cohort of Eastern Poland residents (N= 8,077,671). The area is characterized by a specific type of pollution - Polish smog, featuring high concentrations of particulate matter (PM), benzo(a)pyrenes (BaP) and favourable atmospheric conditions of formation. Medical data were collected from the National Health Fund and the Central Statistical Office. The records included sex and age and the causes of hospitalization. The analysis utilized air quality modeling data from the GEM-AQ system, which allowed to provide daily pollution concentration at the level of each LAU (ie. local administrative units, at municipality level), throughout the observation period. We estimated LAU specific associations of AP concentration using quasi-Poisson generalized additive models. We controlled our models for long-term trends and weather conditions. In the second stage, we pooled LAU-specific estimates with a random-effects meta-analysis. The results are presented as % risk ratio (RR), and 95% confidence intervals (95% CIs) for the two-day moving average of AP concentration on the present day and the day after exposure (ie. LAG0-1). Cluster analysis was performed on LAU levels from 19 variables using the k-mens clustering using the Ward minimum variance method. The set of variables included demographic, ecological, socioeconomic, environmental conditions. Results Over the years 2011-20, we noted 2,141,213 hospitalizations due to CVD, including 139,697 ACS cases (45.2% STEMI). The main triggers for ACS were PM2.5 (RRLAG0-1 1.04 95%CI 1.028-1.053), BaP (RRLAG0-1 1.021 95%CI 1.01-1.032). We identified three distinct clusters: Cluster 1 was characterized by high population density and GPD per capita and highest prevalence of atrial fibrillation. Cluster 2 (40% of the entire population) exhibited significantly high variability, characterized by low population density and GPD per capita, the highest prevalence of heart failure, people drinking alcohol and smoking tobacco. Cluster 3 (7% of the entire population) was in the middle but showed the highest prevalence of hypertension, diabetes and renal failure. Cluster 2 inhabited areas with low concentrations of PMs and BaP and demonstrated increased vulnerability to the effects of PM2.5 and BaP from 3% to 5.2% (P<0.001). For details see Figure 1. Conclusions PM and BaP are important factors associated with the occurrence of MACE. AP exposure should be considered in CVD prevention models. Cluster classification helps in risk stratification and prognosis. Adverse effects of AP can be mitigated by attention to improving socio-economic status and hazardous habits.Associations between AP exposure and ACS

On the dose-response association of fine and ultrafine particles in an urban atmosphere: toxicological outcomes on bronchial cells at realistic doses of exposure at the Air Liquid Interface

Air pollution and particulate matter (PM) are the leading environmental cause of death worldwide. Exposure limits have lowered to increase the protection of human health; accordingly, it becomes increasingly important to understand the toxicological mechanisms on cellular models at low airborne PM concentrations which are relevant for actual human exposure. The use of air liquid interface (ALI) models, which mimic the interaction between airborne pollutants and lung epithelia, is also gaining importance in inhalation toxicological studies. This study reports the effects of ALI direct exposure of bronchial epithelial cells BEAS-2B to ambient PM1 (i.e. particles with aerodynamic diameter lower than 1 μm). Gene expression (HMOX, Cxcl-8, ATM, Gadd45-a and NQO1), interleukin (IL)-8 release, and DNA damage (Comet assay) were evaluated after 24 h of exposure. We report the dose-response curves of the selected toxicological outcomes, together with the concentration-response association and we show that the two curves differ for specific responses highlighting that concentration-response association may be not relevant for understanding toxicological outcomes. Noteworthy, we show that pro-oxidant effects may be driven by the deposition of freshly emitted particles, regardless of the airborne PM1 mass concentration. Furthermore, we show that reference airborne PM1 metrics, namely airborne mass concentration, may not always reflect the toxicological process triggered by the aerosol.These findings underscore the importance of considering different aerosol metrics to assess the toxicological potency of fine and ultrafine particles. To better protect human health additional metrics should be defined, than account for the properties of the entire aerosol mixture including specific as particle size (i.e. particles with aerodynamic diameter lower than 20 nm), the relevant aerosol sources (e.g., traffic combustion, secondary organic aerosol …) as well as their atmospheric processing (freshly emitted vs aged ones).

Atmospheric particulate matter and hypoxaemia in Korean children receiving general anaesthesia: A retrospective analysis.

The association between the concentration of atmospheric particulate matter on the day of surgery and the occurrence of intra-operative hypoxaemia in children receiving general anaesthesia is unclear. To investigate the association between the exposure to particulate matter on the day of surgery and the occurrence of intra-operative hypoxaemia, defined as a pulse oximetry oxygen saturation of less than 90% for more than 1 min, in children. Retrospective study. Single-centre. Children aged 18 years or younger who received general anaesthesia between January 2019 and October 2020. Information on daily levels of particulate matter with a diameter 10 μm or less and 2.5 μm or less measured within a neighbourhood corresponding to the area defined by the hospital's zip code was obtained from publicly available air-quality data. The primary outcome was intra-operative hypoxaemia, defined as a pulse oximetry oxygen saturation of less than 90% lasting for more than 1 min, manually verified by anaesthesiologists using vital sign registry data extracted at 2 s intervals. Of the patients finally analysed, 3.85% (489/13 175) experienced intra-operative hypoxaemia. Higher levels of particulate matter 10 μm or less in diameter (≥81 μg m -3 , 17/275, 6.2%) were associated with an increased occurrence of intra-operative hypoxaemia compared with lower particulate matter concentrations [<81 μg m -3 , 472/12 900, 3.7%; adjusted odds ratio, 1.71; 95% confidence interval (CI), 1.04 to 2.83; P = 0.035]. The level of particulate matter on the day of surgery pose a risk of intra-operative hypoxaemia in children receiving general anaesthesia. If the concentrations of particulate matter 10 μm or less in diameter on the day of surgery are high, children receiving general anaesthesia should be managed with increased caution.

Inflammatory response in mouse lungs to haze episodes under different backgrounds of particulate matter exposure

Particulate matter (PM) toxicity has mostly been investigated through in vitro exposure or tracheal infusion in animal models. However, given the complexity of ambient conditions, most animal studies do not mimic real-life PM exposure. In this work, we established a novel integrated exposure model to study the dynamic inflammatory response and defense strategies in ambient PM-exposed mice. Three groups of male C57BL/6 mice were kept in three chambers with pre-exposure to filtered air (FA), unfiltered air (UFA), or the air with a low PM concentration (PM2.5 ≤ 75 μg/m3) (LPM), respectively, for 37 days. Then all three groups of mice were exposed to haze challenge for 3 days, followed by exposure in filtered air for 7 days to allow recovery. Our results suggest that following a haze challenge, the defense strategies of mice of filtered air (FA) and low PM (LPM) groups comprised a form of “counterattack”, whereas the response of the unfiltered air (UFA) group could be viewed as a “silence”. While the latter strategy protected the lung tissues of mice from acute inflammatory damage, it also foreshadowed the development of chronic inflammatory diseases. These findings contribute to explaining previously documented PM-associated pathogenic mechanisms.

Genome-wide DNA methylation sequencing identifies epigenetic perturbations in the upper airways under long-term exposure to moderate levels of ambient air pollution

While the link between exposure to high levels of ambient particulate matter (PM) and increased incidences of respiratory and cardiovascular diseases is widely recognized, recent epidemiological studies have shown that low PM concentrations are equally associated with adverse health effects. As DNA methylation is one of the main mechanisms by which cells regulate and stabilize gene expression, changes in the methylome could constitute early indicators of dysregulated signaling pathways. So far, little is known about PM-associated DNA methylation changes in the upper airways, the first point of contact between airborne pollutants and the human body. Here, we focused on cells of the upper respiratory tract and assessed their genome-wide DNA methylation pattern to explore exposure-associated early regulatory changes. Using a mobile epidemiological laboratory, nasal lavage samples were collected from a cohort of 60 adults that lived in districts with records of low (Simmerath) or moderate (Stuttgart) PM10 levels in Germany. PM10 concentrations were verified by particle measurements on the days of the sample collection and genome-wide DNA methylation was determined by enzymatic methyl sequencing at single-base resolution. We identified 231 differentially methylated regions (DMRs) between moderately and lowly PM10 exposed individuals. A high proportion of DMRs overlapped with regulatory elements, and DMR target genes were involved in pathways regulating cellular redox homeostasis and immune response. In addition, we found distinct changes in DNA methylation of the HOXA gene cluster whose methylation levels have previously been linked to air pollution exposure but also to carcinogenesis in several instances. The findings of this study suggest that regulatory changes in upper airway cells occur at PM10 levels below current European thresholds, some of which may be involved in the development of air pollution-related diseases.

Investigating the impact of relative humidity and air tightness on PM sedimentation and concentration reduction

Exposure to particulate matter (PM) has a negative impact on human health. The hygroscopicity of PM varies with the chemical composition and particle size, and the sedimentation trends leading to decreased PM concentrations also vary. However, PM hygroscopicity has mostly been considered in terms of outdoor air quality such as visibility and radiation force. Thus, in this study, the relationship between PM and ambient humidity was evaluated through two experiments based on chemical composition and PM particle size analysis, which are representative PM classification methods. Firstly, six aerosols commonly found in indoor and outdoor atmospheres were selected, and the reduction rate of PM number concentrations by particle diameter and mass concentrations (PM10 and PM2.5) was evaluated at different relative humidity(R.H) values. The results indicated that the PM concentration was effectively decreased when indoor R.H was >70%, and the spread of PM was effectively prevented when indoor R.H was >50%. Secondly, measurements were obtained from four houses with different levels of airtightness to clarify the relationship between PM and R.H in actual living environments. Higher airtightness corresponded to lower PM concentrations due to higher R.H, but this effect was not observed when the air change rate was high. Therefore, increasing airtightness to increase R.H may not be a practical solution for reducing indoor PM concentrations in all cases. Our findings suggest that indoor air quality management strategies should consider the complex interactions between PM and ambient humidity in specific building contexts.

Internal corrosion of seabed ‘parked’ steel oil and gas pipelines

Seabed ‘parking’ of steel pipelines is a common practice in the oil and gas industry. For ‘wet parking’ severe internal corrosion, often at the 6 o'clock position, remains an issue, despite the use of corrosion inhibitors and biocides ostensibly to control microbiologically influenced corrosion. Biocides may have undesirable environmental consequences if eventually or accidently released. Recent findings for internal corrosion inside water injection pipelines are reviewed as these have implications for managing the internal corrosion of parked pipelines. After initial oxygen controlled corrosion longer term corrosion can occur under anaerobic conditions. This has implications for corrosion during periods of stagnant conditions and for corrosion under deposits of rusts and other debris. Microbiologically influenced corrosion can increase internal corrosion but only if the nutrients necessary for bacterial metabolism are available. Acceptably low levels of corrosion can be achieved inside ‘wet’ parked pipelines with the use of seawater with low concentrations of particulate matter and low concentrations of microbiologically-critical nutrients.

Inter-comparison of oxidative potential metrics for airborne particles identifies differences between acellular chemical assays

Oxidative potential (OP) has been identified as an important factor underlying the health effects of airborne particulate matter (PM). OP denotes the ability of PM to deplete antioxidants and to form reactive oxygen species (ROS) in the lung. OP can be quantified using a variety of chemical assays and analytical techniques. Despite the widespread use of various OP metrics, there is no consensus or comprehensive inter-laboratory assessment on how these assays compare. In this work for the first time, we compared 11 OP indicators from acellular assays using standard reference material of urban PM. The OP indicators included ascorbic acid, glutathione, glutathione disulfide, cysteine, cystine, dithiothreitol, H2O2, •OH, O2•-, and empirical and theoretical redox potential of simulated lung lining fluid (SLF). The indicators showed first-order kinetics at low PM concentration (25 μg mL−1), whereas the kinetics were non-linear at higher PM concentrations. The indicators demonstrated mainly linear dose-response relationships at PM concentrations 25–100 μg mL−1, following similar trends with water-soluble transition metals, but they were not always proportional to PM concentrations, and demonstrated substantial differences in their sensitivities to PM. The results indicate the importance of using reduced reaction time for reliable OP quantification due to non-linearity in assay responses at high PM concentrations. This work shows that the choice of molecular probes and measurement techniques must be carefully considered when planning studies on OP of ambient air and should importantly include the association of OP metrics with health outcomes.

Increased Shamal winds and dust activity over the Arabian Peninsula during the COVID-19 lockdown period in 2020.

While anthropogenic pollutants have decreased during the lockdown imposed as an effort to contain the spread of the Coronavirus disease 2019 (COVID-19), changes in particulate matter (PM) do not necessarily exhibit the same tendency. This is the case for the eastern Arabian Peninsula, where in March–June 2020, and with respect to the same period in 2016–2019, a 30 % increase in PM concentration is observed. A stronger than normal nocturnal low-level jet and subtropical jet over parts of Saudi Arabia, in response to anomalous convection over the tropical Indian Ocean, promoted enhanced and more frequent episodes of Shamal winds over the Arabian Peninsula. Increased surface winds associated with the downward mixing of momentum to the surface fostered, in turn, dust lifting and increased PM concentrations. The stronger low-level winds also favoured long-range transport of aerosols, changing the PM values downstream. The competing effects of reduced anthropogenic and increased dust concentrations leave a small positive signal (<5 W m−2) in the net surface radiation flux (Rnet), with the former dominating during daytime and the latter at night. However, in parts of the Arabian Gulf, Sea of Oman and Iran Rnet increased by >20 W m−2 with respect to the baseline period, owing to a clearer environment and weaker winds. It is concluded that a reduction in anthropogenic emissions due to the lockdown does not necessarily go hand in hand with lower particulate matter concentrations. Therefore, emissions reduction strategies need to account for feedback effects in order to reach the planned long-term outcomes.

Acute Effects of Particulate Matter on All-Cause Mortality in Urban, Rural, and Suburban Areas, Italy.

Background: Short-term exposure to particulate matter (PM) has been related to mortality worldwide. Most evidence comes from studies conducted in major cities, while little is known on the effects of low concentrations of PM and in less urbanized areas. We aim to investigate the relationship between PM and all-cause mortality at national level in Italy. Methods: Daily numbers of all-cause mortality were collected for all 8092 municipalities of Italy, from 2006 to 2015. A satellite-based spatiotemporal model was developed to estimate daily PM10 (inhalable particles) and PM2.5 (fine particles) concentrations at 1-km resolution. Multivariate Poisson regression models were fit to estimate the association between daily PM and mortality at province level, and then, results were pooled with a random-effects meta-analysis. Associations were estimated by combination of age and sex and degree of urbanization of the municipalities. Flexible functions were estimated to explore the shape of the associations at low PM concentrations. Results: We analyzed 5,884,900 deaths (40% among subjects older than 85 years, 60% occurring outside the main urban areas). National daily mean (interquartile range) PM10 and PM2.5 concentrations were 23 (14) μg/m3 and 15 (11) μg/m3, respectively. Relative increases of mortality per 10 μg/m3 variation in lag 0–5 (average of last six days since death) PM10 and PM2.5 were 1.47% (95% Confidence Intervals (CI): 1.15%, 1.79%) and 1.96% (1.33%, 2.59%), respectively. Associations were highest among elderly and women for PM10 only, similar between rural and urbanized areas, and were present even at low concentrations, e.g., below WHO guidelines. Conclusions: Air pollution was robustly associated with peaks in daily all-cause mortality in Italy, both in large cities and in less urbanized areas of Italy. Current WHO Air Quality Guidelines (2021) for PM10 and PM2.5 are not sufficient to protect public health.

Air Pollution Analysis during the Lockdown on the City of Milan

From February 2020, the progressive adoption of measures to contain coronavirus’s contagion has resulted in a sudden change in anthropogenic activities in Italy, especially in Lombardy. From a scientific point of view, this situation represents a unique laboratory for understanding and predicting the consequences of specific measures aimed at improving air quality. In this work, the lockdown effect on Milan’s (Italy) air quality was analyzed. The PM10 and PM2.5 values were measured by the ARPA Lombardia, and the real-time on-road (ROM) air quality monitoring network indicates the seasonality of these pollutants, which typically record the highest values in the coldest months of the year. The 10-year particulate matter concentrations analysis shows a PM10 reduction of 35% from 2010 to 2020. March 2020 data analysis shows an alternation of days with higher and lower particulate matter concentrations; values decrease in pollutants concentrations of 16%, respective to 2018. The complexity of the phenomena related to the atmospheric particulates formation, transport, and accumulation is highlighted by some circumstances, such as the Sahara dust events. The study showed that the trend of a general pollutant concentration reduction should be attributed to the decrease in emissions (specifically, from the transport sector) from the variation of meteorological and environmental conditions.

Influence of a weak typhoon on the vertical distribution of air pollution in Hong Kong: A perspective from a Doppler LiDAR network

High particulate matter (PM) and ozone (O3) concentration in Hong Kong are frequently observed during the summertime typhoon season. Despite the critical effect of a typhoon on air pollution, contributions of vertical wind profile and cloud movement during transboundary air pollution (TAP) on surface PM and O3 concentration have yet to be fully understood. This work is the first study to apply a network of Doppler light detection and ranging (LiDAR) as well as back trajectory analysis to comprehensively analyze the effect of a weak Typhoon (Danas) occurring during 16-19 July 2019 on different variations in PM and O3 concentration. During the typhoon Danas, three types of surface air pollution with five episodes were identified: (1) low PM and high O3 concentration; (2) co-occurring high PM and O3 concentration and (3) high PM and low O3 concentration. Employing our 3D Real-Time Atmospheric Monitoring System (3DREAMs) along with surface observations, we found the important role of TAP in the increases in surface PM and O3 concentration with significant vertical wind shear that transported air pollutants at upper levels, and strong vertical mixing that brought air pollutants to the ground level. Cloud movement related to typhoon periphery, as well as high solar radiation due to sinking motion and remote transport by continental wind, have an impact on local O3 concentration. For the substantial difference in O3 concentration between two air quality measurement sites, the similar vertical aerosol distributions and wind profiles suggest the comparable TAP contributions at the two sites and thus infer the critical role of local O3 photochemical process in the O3 difference. This work comprehensively reveals the influences of a weak typhoon on variations in PM and O3 during the five episodes, providing important references for air quality monitoring and forecast in regions under the influence of typhoon.

Short-term effects of particulate matter on cardiovascular morbidity in Italy: a national analysis.

We aimed at investigating the relationship between particulate matter (PM) and daily admissions for cardiovascular diseases (CVDs) at national level in Italy. Daily numbers of cardiovascular hospitalizations were collected for all 8084 municipalities of Italy, in the period 2013-2015. A satellite-based spatiotemporal model was used to estimate daily PM10 (inhalable particles) and PM2.5 (fine particles) concentrations at 1-km2 resolution. Multivariate Poisson regression models were fit to estimate the association between daily PM and cardiovascular admissions. Flexible functions were estimated to explore the shape of the associations at low PM concentrations, also in non-urban areas. We analysed 2154810 acute hospitalizations for CVDs (25% stroke, 24% ischaemic heart diseases, 22% heart failure, and 5% atrial fibrillation). Relative increases of total cardiovascular admissions, per 10 µg/m3 variation in PM10 and PM2.5 at lag 0-5 (average of last 6 days since admission), were 0.55% (95% confidence intervals: 0.32%, 0.77%) and 0.97% (0.67%, 1.27%), respectively. The corresponding estimates for heart failure were 1.70% (1.28%, 2.13%) and 2.66% (2.09%, 3.23%). We estimated significant effects of PM10 and PM2.5 also on ischaemic heart diseases, myocardial infarction, atrial fibrillation, and ischaemic stroke. Associations were similar between less and more urbanized areas, and persisted even at low concentrations, e.g. below WHO guidelines. PM was robustly associated with peaks in daily cardiovascular admissions, especially for heart failure, both in large cities and in less urbanized areas of Italy. Current WHO Air Quality Guidelines for PM10 and PM2.5 are not sufficient to protect public health.

Short-term effects of ambient particles on mortality in Italy - a national approach

Background. Short-term exposure to particulate matter (PM) has been related to mortality worldwide. Most evidence comes from studies conducted in major cities, while little is known on the effects of low concentrations of PM and in less urbanized areas. We aim to investigate the relationship between PM and all-cause mortality at national level in Italy.Methods. Daily numbers of all-cause mortality were collected for all 8,092 municipalities of Italy, from 2006 to 2015. A satellite-based spatiotemporal model was developed to estimate daily PM10 (inhalable particles) and PM2.5 (fine particles) concentrations at 1-km resolution. Multivariate Poisson regression models were fit to estimate the association between daily PM and mortality at province level, then results were pooled with a random-effects meta-analysis. Associations were estimated by age, sex and degree of urbanization of the municipalities. Flexible functions were estimated to explore the shape of the associations at low PM concentrations.Results. We analyzed 6,552,257 deaths (40% among subjects older than 85 years, 55% occurring outside the main urban areas). National daily mean (interquartile range) PM10 and PM2.5 concentrations were 23 (12) μg/m3 and 17 (9) μg/m3, respectively. Relative increases of mortality, per 10 μg/m3 variation in lag 0-5 (average of last six days since death) PM10 and PM2.5, were 0.80% (95% Confidence Intervals [CI]: 0.58%, 1.01%) and 0.72% (0.34%, 1.09%) respectively. Associations were highest among elderly and women, similar between rural and urbanized areas, and were present even at low concentrations, e.g. below WHO guidelines. Conclusions. Air pollution was robustly associated with peaks in daily all-cause mortality in Italy, both in large cities and in less urbanized areas of Italy. Current WHO Air Quality Guidelines for PM10 and PM2.5 are not sufficient to protect public health.

Two decades of trends in urban particulate matter concentrations across Australia

Australia is a highly developed country with low population density. Capital cities are situated mainly around the coastline and are subjected to different meteorological conditions. This complex set of drivers is expected to result in varying trends in particulate matter (PM) mass concentrations in urban ambient air across the country. Thus, the aim of this study was to determine the long-term trends in PM10 and PM2.5 concentrations in capital cities, and to analyse the factors that influenced such trends. The spatial variability of PM concentrations within the capital cities was first established to identify representative stations. Then trends were determined using the Mann-Kendall trend test, Sen's slope, and the generalised additive model. The results show that, in general, the PM concentrations in Australian cities are relatively low (12.1–21.7 μg m−3 mean daily PM10 and 4.6–8.7 μg m−3 mean daily PM2.5) and within the WHO daily limit 95% of the time. Over the past two decades, very small declines of 8.0 × 10−5–1.1 × 10−3 μg m−3.yr−1 for PM10 and 7.7 × 10−5–2.6 × 10−3 μg m−3.yr−1 for PM2.5 were observed while some stations exhibited increase in concentration based on available data; more stations showed a significant monotonic decline for PM10 than PM2.5. This is attributed to the effectiveness of the implemented emission reduction policies particularly for vehicle exhaust and power generation, given the simultaneous increase in the demand for energy and the number of vehicles over the last two decades. Regarding climate, in the coastal cities of Sydney and Brisbane, high rainfall and strong winds aid in maintaining low PM concentrations despite the significant anthropogenic emissions, while higher PM levels in Darwin can be attributed to its tropical savannah climate, which makes it prone to bushfires and necessitates regular prescribed burnings. PM concentrations increase when exceptional events such as bushfires and dust storms are induced by the extreme climate variability. Further reduction of PM concentrations in Australian cities is unlikely, considering the expanding urbanisation and the changing climate.

Assessment of Ventilation Efficiency in School Classrooms Based on Indoor–Outdoor Particulate Matter and Carbon Dioxide Measurements

The concentration of indoor suspended particulate matter is considered to be one of the main factors that affect health and quality of life. In Poland, in response to the pressure of public opinion, a few thousand air purifiers have been installed in public buildings where children spend time. However, another factor that also impacts upon the quality of indoor air, namely increased CO2 mixing ratios, is frequently overlooked. The only way to remove CO2 excess from interiors is through intensive ventilation. This is often an action at odds with the need to maintain low concentrations of particulate matter in indoor air. Two methods are presented to assess the rate of air exchange using CO2 or particulate matter as a tracer. One of the methods using indoor/outdoor PM (particulate matter) concentrations is based on the use of box models for analysis. The second one uses indoor CO2 concentration change analysis. At the tested locations, they showed large deviations of the determined values of the air exchange coefficients from its limits. Both methods showed consistent ventilation parameters estimation.

Impacts of meteorology and emission control on the abnormally low particulate matter concentration observed during the winter of 2017

As the capital of China, Beijing is the subject of great concern regarding atmospheric pollution, especially that of fine particulate matter (PM2.5). In winter 2017 (i.e., November 2017 to February 2018), PM2.5 concentration in Beijing decreased to its lowest value in the past ten years. In this study, we sought to investigate the impacts of meteorology and emission control on this abnormally low pollution phenomenon. Weather Research and Forecasting coupled with Chemistry (WRF-Chem) simulations show that sensitivity to meteorological factors accounts for approximately 51% of the observed change between winters 2016 and 2017 in Beijing. We further compared the pollution dispersion condition of winters 2016 and 2017 in terms of large-scale circulation patterns and local mixing layer heights (MLHs). The meteorological condition in 2017 was characterized by stronger wind speed (WS) and higher MLH. We classified circulation patterns into two types using the obliquely rotated Principal Component Analysis in T-mode (T-PCA) method. Active weather was found to be associated with high MLH, high near-surface WS, and high ventilation coefficient (VC), which favors the dispersion of pollutants. In contrast, the changes of meteorological variables and pollution conditions are almost opposite for stable weather. Active weather amounted to 73 and 85 days for winters 2016 and 2017, respectively. Stable weather conditions prevailed on 46 days in winter 2016, and 32 days in 2017. Less stable weather during winter 2017 compared with that of winter 2016 possibly favored efficient ventilation of boundary-layer pollution. A lack of persistent stable weather also contributed to low PM2.5 concentration in 2017. This research is important for air-pollution assessment and regional environmental management.

Improving PM Collection of EPA Other Test Method (OTM) 36 Precutter

The Environmental Protection Agency (EPA) regulates the amount of particulate matter (PM) emitted by different industrial processes to protect human health and the environment. EPA Test Method 5 is the standard method to determine PM emissions from stationary sources. However, moisture present in emission sources can yield overestimated PM concentrations when using EPA Method 5. Alternatively, EPA Other Test Method (OTM) 36 regulates the method used for determining the concentration of PM2.5 emissions, which are particles with a diameter of less than 2.5 micrometers, from moisture-saturated stationary source gas streams. The EPA has found that the OTM 36 sampling train measures lower PM concentrations than actual concentrations in the emission source. This is because the sampling train’s precutter nozzle, which is the first instrument of a sampling train placed into an emission source, collects particles at smaller sizes than intended, preventing these particles from being measured by the sampling train. The purpose of this research is to create a new precutter nozzle design that allows the PM sampling train to more accurately measure PM to reflect actual concentrations in emission sources tested by OTM 36. By using computational fluid dynamics (CFD) simulations in ANSYS Fluent program, the collection efficiency of different dimensions of the new precutter nozzle was calculated to choose the best design that more accurately collects PM. Based on this objective, a precutter nozzle with a 7-degree half-cone angle and 3-cm throat length was chosen as the most viable design.

Metal-containing Particulate Matter and Associated Reduced Olfactory Identification Ability in Children from an Area of High Atmospheric Exposure in Mexico City.

Air pollution has been linked to poor olfactory function in human adults. Among pollutants, particulate matter (PM) is especially relevant, as it may contain toxic metal ions that can reach the brain via olfactory pathways. Our purpose was to investigate the relation between atmospheric PM and olfactory identification performance in children. Using a validated method, we tested the olfactory identification performance of 120 children, 6-12 years old, from two locations in Mexico City: a focal group (n = 60) from a region with high PM levels and a control group of equal size and similar socioeconomic level from a region with markedly lower PM concentrations. Groups were matched for age and sex. Concentrations of manganese and lead in the hair of participants were determined as biomarkers of exposure. Daily outdoor PM levels were obtained from official records, and indoor PM levels were measured in the children's classrooms. Official records confirmed higher levels of outdoor PM in the focal region during the days of testing. We also found higher classroom PM concentrations at the focal site. Children from the focal site had on average significantly lower olfactory identification scores than controls, and hair analysis showed significantly higher levels of manganese for the focal children but no difference in lead. Children appear to be vulnerable to the effects of air pollution on olfactory identification performance, and metal-containing particles likely play a role in this. Olfactory tests provide a sensitive, noninvasive means to assess central nervous function in populations facing poor air quality.

Effects of short-term exposure to particulate matter air pollution on cognitive performance

This paper assesses the effect of short-term exposure to particulate matter (PM) air pollution on human cognitive performance via a double cross over experimental design. Two distinct experiments were performed, both of which exposed subjects to low and high concentrations of PM. Firstly, subjects completed a series of cognitive tests after being exposed to low ambient indoor PM concentrations and elevated PM concentrations generated via candle burning, which is a well-known source of PM. Secondly, a different cohort underwent cognitive tests after being exposed to low ambient indoor PM concentrations and elevated ambient outdoor PM concentrations via commuting on or next to roads. Three tests were used to assess cognitive performance: Mini-Mental State Examination (MMSE), the Stroop Color and Word test, and Ruff 2 & 7 test. The results from the MMSE test showed a statistically robust decline in cognitive function after exposure to both the candle burning and outdoor commuting compared to ambient indoor conditions. The similarity in the results between the two experiments suggests that PM exposure is the cause of the short-term cognitive decline observed in both. The outdoor commuting experiment also showed a statistically significant short-term cognitive decline in automatic detection speed from the Ruff 2 and 7 selective attention test. The other cognitive tests, for both the candle and commuting experiments, showed no statistically significant difference between the high and low PM exposure conditions. The findings from this study are potentially far reaching; they suggest that elevated PM pollution levels significantly affect short term cognition. This implies average human cognitive ability will vary from city to city and country to country as a function of PM air pollution exposure.