Spatial and temporal variation in fine particulate matter mass and chemical composition: the Middle East Consortium for Aerosol Research Study

Comprehensive chemical characterization of PM2.5 in the large East Mediterranean-Middle East city of Beirut, Lebanon

The chemical composition of PM_2.5 at two sites in Lebanon, a country in the East Mediterranean - Middle East region, is investigated in the spring and summer seasons. The average PM_2.5 concentrations were of (29 ± 16) µg/m³ for Beirut urban site and (32 ± 14) µg/m³ for Beirut suburban site. This study showed that the geographic location of the East Mediterranean region, such as its proximity to the Mediterranean Sea and the dust storm intrusion are a significant contributor to the high PM levels from natural sources, which cannot be mitigated, rendering the PM_2.5 WHO annual Air Quality guideline unattainable due to high natural background, which also applies to the entire Middle East region. Turkey and Eastern Europe are the dominant origin of air masses throughout our sampling days, suggesting the long-range transport as an important potential contributor to the high observed concentrations of V, Ni, and sulfate in this region most probably in other East Mediterranean countries than Lebanon too. Main local sources determined through the chemical speciation including organics are road transport, resuspension of dust and diesel private generators. A health risk assessment of airborne metals was performed and the carcinogenic risk for all the metals exceeded by 42 (adults) and 14 (children) times the acceptable risk level (10^-6) at both sites. Vanadium was the predominant carcinogenic metal, emphasizing the need to replace energy production with cleaner energy on a regional level and highlighting the severe impact of air pollution on the health of inhabitants in this region's main cities.

Particulate Air Pollution Exposure and Stroke among Adults in Israel

Stroke is the second most common cause of death and disability in the world. Many studies have found fine particulate matter (PM2.5) exposure to be associated with an increased risk of atherosclerotic cardiovascular disease, mostly focusing on ischemic heart disease and acute myocardial infarction. In a national analysis conducted in Israel-an area with unique climate conditions and high air pollution levels, we estimated the association between short-term PM2.5 exposure and ischemic stroke, intracerebral hemorrhage (ICH), or transient ischemic attacks (TIA). Using the Israeli National Stroke Registry, we obtained information on all stroke cases across Israel in 2014-2018. We obtained daily PM2.5 exposures from spatiotemporally resolved exposure models. We restricted the analytical data to days in which PM2.5 levels did not exceed the Israeli 24 h standard (37.5 µg/m3). We repeated the analysis with a stratification by sociodemographic characteristics and comorbidities. For all outcomes, the exposure-response curves were nonlinear. PM2.5 exposure was associated with a higher ischemic stroke risk, with larger effect estimates at higher exposure levels. Although nonsignificant, the exposure-response curve for TIA was similar. The associations with ICH were nonsignificant throughout the PM2.5 exposure distribution. The associations with ischemic stroke/TIA were larger among women, non-Jewish individuals, older adults, and individuals with diabetes, hypertension, and ischemic heart disease. In conclusion, short-term PM2.5 exposure is associated with a higher risk for ischemic stroke and possibly TIA, even when PM2.5 concentrations do not exceed the Israeli air quality guideline threshold. Vulnerability to the air pollution effects differed by age, sex, ethnicity, and comorbidities.

Urban Particulate Matter Hazard Mapping and Monitoring Site Selection in Nablus, Palestine

Few air pollution studies have been applied in the State of Palestine and all showed an increase in particulate matter concentrations above WHO guidelines. However, there is no clear methodology for selecting monitoring locations. In this study, a methodology based on GIS and locally calibrated low-cost sensors was tested. A GIS-based weighted overlay summation process for the potential sources of air pollution (factories, quarries, and traffic), taking into account the influence of altitude and climate, was used to obtain an air pollution hazard map for Nablus, Palestine. To test the methodology, eight locally calibrated PM sensors (AirUs) were deployed to measure PM2.5 concentrations for 55 days from 7 January to 2 March 2022. The results of the hazard map showed that 82% of Nablus is exposed to a high and medium risk of PM pollution. Sensors’ readings showed a good match between the hazard intensity and PM concentrations. It also shows an elevated PM2.5 concentrations above WHO guidelines in all areas. In summary, the overall average for PM2.5 in the Nablus was 48 µg/m3. This may indicate the effectiveness of mapping methodology and the use of low-cost, locally calibrated sensors in characterizing air quality status to identify the potential remediation options.

Air Pollution and Autism Spectrum Disorder in Israel: A Negative Control Analysis

BACKGROUND

Residual confounding is a major concern for causal inference in observational studies on air pollution-autism spectrum disorder (ASD) associations. This study is aimed at assessing confounding in these associations using negative control exposures.

METHODS

This nested case-control study included all children diagnosed with ASD (detected through 31 December 2016) born during 2007-2012 in Israel and residing in the study area (N = 3,843), and matched controls of the same age (N = 38,430). We assigned individual house-level exposure estimates for each child. We estimated associations using logistic regression models, mutually adjusted for all relevant exposure periods (prepregnancy, pregnancy, and postnatal). We assessed residual confounding using postoutcome negative control exposure at age 28-36 months.

RESULTS

In mutually adjusted models, we observed positive associations with ASD for postnatal exposures to NOx (odds ratio per interquartile range, 95% confidence interval: 1.19, 1.02-1.38) and NO2 (1.20, 1.00-1.43), and gestational exposure to PM2.5-10 (1.08, 1.01-1.15). The result for the negative control period was 1.04, 0.99-1.10 for PM2.5, suggesting some residual confounding, but no associations for PM2.5-10 (0.98, 0.81-1.18), NOx (1.02, 0.84-1.25), or NO2 (0.98, 0.81-1.18), suggesting no residual confounding.

CONCLUSIONS

Our results further support a hypothesized causal link with ASD that is specific to postnatal exposures to traffic-related pollution.

Estimation of ambient PM2.5 in Iraq and Kuwait from 2001 to 2018 using machine learning and remote sensing

Iraq and Kuwait are in a region of the world known to be impacted by high levels of fine particulate matter (PM2.5) attributable to sources that include desert dust and ambient pollution, but historically have had limited pollution monitoring networks. The inability to assess PM2.5 concentrations have limited the assessment of the health impact of these exposures, both in the native populations and previously deployed military personnel. As part of a Department of Veterans Affairs Cooperative Studies Program health study of land-based U.S. military personnel who were previously deployed to these countries, we developed a novel approach to estimate spatially and temporarily resolved daily PM2.5 exposures 2001-2018. Since visibility is proportional to ground-level particulate matter concentrations, we were able to take advantage of extensive airport visibility data that became available as a result of regional military operations over this time period. First, we combined a random forest machine learning and a generalized additive mixed model to estimate daily high resolution (1 km × 1 km) visibility over the region using satellite-based aerosol optical depth (AOD) and airport visibility data. The spatially and temporarily resolved visibility data were then used to estimate PM2.5 concentrations from 2001 to 2018 by converting visibility to PM2.5 using empirical relationships derived from available regional PM2.5 monitoring stations. We adjusted for spatially resolved meteorological parameters, land use variables, including the Normalized Difference Vegetation Index, and satellite-derived estimates of surface dust as a measure of sandstorm activity. Cross validation indicated good model predictive ability (R2 = 0.71), and there were considerable spatial and temporal differences in PM2.5 across the region. Annual average PM2.5 predictions for Iraq and Kuwait were 37 and 41 μg/m3, respectively, which are greater than current U.S. and WHO standards. PM2.5 concentrations in many U.S. bases and large cities (e.g. Bagdad, Balad, Kuwait city, Karbala, Najaf, and Diwaniya) had annual average PM2.5 concentrations above 45 μg/m3 with weekly averages as high as 150 μg/m3 depending on calendar year. The highest annual PM2.5 concentration for both Kuwait and Iraq were observed in 2008, followed by 2009, which was associated with extreme drought in these years. The lowest PM2.5 values were observed in 2014. On average, July had the highest concentrations, and November had the lowest values, consistent with seasonal patterns of air pollution in this region. This is the first study that estimates long-term PM2.5 exposures in Iraq and Kuwait at a high resolution based on measurements data that will allow the study of health effects and contribute to the development of regional environmental policies. The novel approach demonstrated may be used in other parts of the world with limited monitoring networks.

Pollution Characteristics of Particulate Matter (PM2.5 and PM10) and Constituent Carbonaceous Aerosols in a South Asian Future Megacity

The future megacity of Faisalabad is of prime interest when considering environmental health because of its bulky population and abundant industrial and anthropogenic sources of coarse particles (PM10) and fine airborne particulate matter (PM2.5). The current study was aimed to investigate the concentration level of PM2.5 and PM10, also the characterization of carbonaceous aerosols including organic carbon (OC), elemental carbon (EC) and total carbon (TC) in PM2.5 and PM10 samples collected from five different sectors (residential, health, commercial, industrial, and vehicular zone). The data presented here are the first of their kind in this sprawling city having industries and agricultural activities side by side. Results of the study revealed that the mass concentration of PM2.5 and PM10 is at an elevated level throughout Faisalabad, with ambient PM2.5 and PM10 points that constantly exceeded the 24-h standards of US-EPA, and National Environment Quality Standards (NEQS) which poses harmful effects on the quality of air and health. The total carbon concentration varied between 21.33 and 206.84 μg/m3, and 26.08 and 211.15 μg/m3 with an average of 119.16 ± 64.91 μg/m3 and 124.71 ± 64.38 μg/m3 for PM2.5 in summer and winter seasons, respectively. For PM10, the concentration of TC varied from 34.52 to 289.21 μg/m3 with an average of 181.50 ± 87.38 μg/m3 (for summer season) and it ranged between 44.04 and 300.02 μg/m3 with an average of 191.04 ± 87.98 μg/m3 (winter season), respectively. No significant difference between particulate concentration and weather parameters was observed. Similarly, results of air quality index (AQI) and pollution index (PI) stated that the air quality of Faisalabad ranges from poor to severely pollute. In terms of AQI, moderate pollution was recorded on sampling sites in the following order; Ittehad Welfare Dispensary > Saleemi Chowk > Kashmir Road > Pepsi Factory, while at Nazria Pakistan Square and Allied Hospital, higher AQI values were recorded. The analysis and results presented in this study can be used by policy-makers to apply rigorous strategies that decrease air pollution and the associated health effects in Faisalabad.

Metabolomic and metallomic profile differences between Veterans and Civilians with Pulmonary Sarcoidosis

Sarcoidosis is a disorder characterized by granulomatous inflammation of unclear etiology. In this study we evaluated whether veterans with sarcoidosis exhibited different plasma metabolomic and metallomic profiles compared with civilians with sarcoidosis. A case control study was performed on veteran and civilian patients with confirmed sarcoidosis. Proton nuclear magnetic resonance spectroscopy (1H NMR), hydrophilic interaction liquid chromatography mass spectrometry (HILIC-MS) and inductively coupled plasma mass spectrometry (ICP-MS) were applied to quantify metabolites and metal elements in plasma samples. Our results revealed that the veterans with sarcoidosis significantly differed from civilians, according to metabolic and metallomics profiles. Moreover, the results showed that veterans with sarcoidosis and veterans with COPD were similar to each other in metabolomics and metallomics profiles. This study suggests the important role of environmental risk factors in the development of different molecular phenotypic responses of sarcoidosis. In addition, this study suggests that sarcoidosis in veterans may be an occupational disease.

Spatial and temporal variations of PM2.5 mass closure and inorganic PM2.5 in the Southeastern U.S

Fine particulate matter (i.e., PM_2.5) has gained extensive attention owing to its adverse effects. The impacts of PM_2.5 may vary in time and space due to the spatiotemporal variations of PM_2.5 number size distribution and chemical compositions. This research analyzed the latest PM_2.5 chemical compositions measurements with an aim to better understand the dynamic changes of PM_2.5 in response to emission reductions due to the new regulations. The particulate measurements from the Southeastern Aerosol Research and Characterization (SEARCH) network between 2001 and 2016 were analyzed for the spatiotemporal variations of PM_2.5 and inorganic PM_2.5 (iPM_2.5 = SO₄^2- + NH₄⁺ + NO₃^-) chemical compositions in the Southeastern United States (U.S.). It was discovered that PM_2.5 and iPM_2.5 mass concentrations exhibited significant downward trends in 2001-2016. Both PM_2.5 and iPM_2.5 mass concentrations were higher at urban and inland sites than rural/suburban and coastal sites. The higher iPM_2.5 concentrations at agricultural sites were attributed to the influences of ammonia (NH₃) emissions from animal feeding operations (AFOs). The iPM_2.5 was the dominant contributor to PM_2.5 in 2001-2016 at the coastal sites, whereas organic carbon matter (OCM) was the major contributor to PM_2.5 after 2011 at the inland sites. Our data analysis suggests that significant decrease of PM_2.5 concentrations is attributed to the reductions in nitrogen oxides (NO_x) and sulfur dioxide (SO₂) emissions in 2001-2016. Findings from this research provide insights into the development of effective PM_2.5 control strategies and assessment of air pollutants exposure.

Use of Low-Cost Ambient Particulate Sensors in Nablus, Palestine with Application to the Assessment of Regional Dust Storms

Few air pollutant studies within the Palestinian territories have been reported in the literature. In March–April and May–June of 2018, three low-cost, locally calibrated particulate monitors (AirU’s) were deployed at different elevations and source areas throughout the city of Nablus in Northern West Bank, Palestine. During each of the three-week periods, high but site-to-site similar particulate matter less than 2.5 µm in aerodynamic diameter (PM2.5) and less than 10 µm (PM10) concentrations were observed. The PM2.5 concentrations at the three sampling locations and during both sampling periods averaged 38.2 ± 3.6 µg/m3, well above the World Health Organization’s (WHO) 24 h guidelines. Likewise, the PM10 concentrations exceeded or were just below the WHO’s 24 h guidelines, averaging 48.5 ± 4.3 µg/m3. During both periods, short episodes were identified in which the particulate levels at all three sites increased substantially (≈2×) above the regional baseline. Air mass back trajectory analyses using U.S. National Oceanic and Atmospheric Administration’s (NOAA) Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model suggested that, during these peak episodes, the arriving air masses spent recent days over desert areas (e.g., the Saharan Desert in North Africa). On days with regionally low PM2.5 concentrations (≈20 µg/m3), back trajectory analysis showed that air masses were directed in from the Mediterranean Sea area. Further, the lower elevation (downtown) site often recorded markedly higher particulate levels than the valley wall sites. This would suggest locally derived particulate sources are significant and may be beneficial in the identification of potential remediation options.

Regional Inhaled Deposited Dose of Urban Aerosols in an Eastern Mediterranean City

We calculated the regional deposited dose of inhaled particulate matter based on number/mass concentrations in Amman, Jordan. The dose rate was the highest during exercising but was generally lower for females compared to males. The fine particles dose rate was 1010–1011 particles/h (101–102 µg/h). The PM10 dose rate was 49–439 µg/h for males and 36–381 µg/h for females. While resting, the PM10 deposited in the head airways was 67–77% and 8–12% in the tracheobronchial region. When exercising, the head airways received 37–44% of the PM10, whereas the tracheobronchial region received 31–35%. About 8% (exercise) and 14–16% (rest) of the PM2.5 was received in the head airways, whereas the alveolar received 74–76% (exercise) and 54–62% (rest). Extending the results for common exposure scenarios in the city revealed alarming results for service workers and police officers; they might receive PM2.5 and 220 µg/h PM10 while doing their duty on main roads adjacent to traffic. This is especially critical for a pregnant police officer. Outdoor athletic activities (e.g., jogging along main roads) are associated with high PM2.5 and PM10 dose rates (100 µg/h and ~425 µg/h, respectively).

Comparison of Measurement-Based Methodologies to Apportion Secondary Organic Carbon (SOC) in PM2.5: A Review of Recent Studies

Secondary organic aerosol (SOA) is known to account for a major fraction of airborne particulate matter, with significant impacts on air quality and climate at the global scale. Despite the substantial amount of research studies achieved during these last decades, the source apportionment of the SOA fraction remains difficult due to the complexity of the physicochemical processes involved. The selection and use of appropriate approaches are a major challenge for the atmospheric science community. Several methodologies are nowadays available to perform quantitative and/or predictive assessments of the SOA amount and composition. This review summarizes the current knowledge on the most commonly used approaches to evaluate secondary organic carbon (SOC) contents: elemental carbon (EC) tracer method, chemical mass balance (CMB), SOA tracer method, radiocarbon (14C) measurement and positive matrix factorization (PMF). The principles, limitations, challenges and good practices of each of these methodologies are discussed in the present article. Based on a comprehensive—although not exhaustive—review of research papers published during the last decade (2006–2016), SOC estimates obtained using these methodologies are also summarized for different regions across the world. Conclusions of some studies which are directly comparing the performances of different methodologies are then specifically discussed. An overall picture of SOC contributions and concentrations obtained worldwide for urban sites under similar conditions (i.e., geographical and seasonal ones) is also proposed here. Finally, further needs to improve SOC apportionment methodologies are also identified and discussed.

Monitoring of air pollution levels related to Charilaos Trikoupis Bridge

Charilaos Trikoupis bridge is the longest cable bridge in Europe that connects Western Greece with the rest of the country. In this study, six air pollution monitoring campaigns (including major regulated air pollutants) were carried out from 2013 to 2015 at both sides of the bridge, located in the urban areas of Rio and Antirrio respectively. Pollution data were statistically analyzed and air quality was characterized using US and European air quality indices. From the overall campaign, it was found that air pollution levels were below the respective regulatory thresholds, but once at the site of Antirrio (26.4 and 52.2μg/m³ for PM_2.5 and ΡΜ₁₀, respectively) during the 2nd winter period. Daily average PM₁₀ and PM_2.5 levels from two monitoring sites were well correlated to gaseous pollutant (CO, NO, NO₂, NO_x and SO₂) levels, meteorological parameters and factor scores from Positive Matrix Factorization during the 3-year period. Moreover, the elemental composition of PM₁₀ and PM_2.5 was used for source apportionment. That analysis revealed that major emission sources were sulfates, mineral dust, biomass burning, sea salt, traffic and shipping emissions for PM₁₀ and PM_2.5, for both Rio and Antirrio. Seasonal variation indicates that sulfates, mineral dust and traffic emissions increased during the warm season of the year, while biomass burning become the dominant during the cold season. Overall, the contribution of the Charilaos Trikoupis bridge to the vicinity air pollution is very low. This is the result of the relatively low daily traffic volume (~10,000 vehicles per day), the respective traffic fleet composition (~81% of the traffic fleet are private vehicles) and the speed limit (80km/h) which does not favor traffic emissions. In addition, the strong and frequent winds further contribute to the rapid dispersion of the emitted pollutants.

Source apportionments of ambient fine particulate matter in Israeli, Jordanian, and Palestinian cities

This manuscript evaluates spatial and temporal variations of source contributions to ambient fine particulate matter (PM_2.5) in Israeli, Jordanian, and Palestinian cities. Twenty-four hour integrated PM_2.5 samples were collected every six days over a 1-year period (January to December 2007) in four cities in Israel (West Jerusalem, Eilat, Tel Aviv, and Haifa), four cities in Jordan (Amman, Aqaba, Rahma, and Zarka), and three cities in Palestine (Nablus, East Jerusalem, and Hebron). The PM_2.5 samples were analyzed for major chemical components, including organic carbon and elemental carbon, ions, and metals, and the results were used in a positive matrix factorization (PMF) model to estimate source contributions to PM_2.5 mass. Nine sources, including secondary sulfate, secondary nitrate, mobile, industrial lead sources, dust, construction dust, biomass burning, fuel oil combustion and sea salt, were identified across the sampling sites. Secondary sulfate was the dominant source, contributing 35% of the total PM_2.5 mass, and it showed relatively homogeneous temporal trends of daily source contribution in the study area. Mobile sources were found to be the second greatest contributor to PM_2.5 mass in the large metropolitan cities, such as Tel Aviv, Hebron, and West and East Jerusalem. Other sources (i.e. industrial lead sources, construction dust, and fuel oil combustion) were closely related to local emissions within individual cities. This study demonstrates how international cooperation can facilitate air pollution studies that address regional air pollution issues and the incremental differences across cities in a common airshed. It also provides a model to study air pollution in regions with limited air quality monitoring capacity that have persistent and emerging air quality problems, such as Africa, South Asia and Central America.

Use of visual range measurements to predict fine particulate matter exposures in Southwest Asia and Afghanistan

Military personnel deployed to Southwest Asia and Afghanistan were exposed to high levels of ambient particulate matter (PM). However, quantitative ambient exposure data for conducting health studies are limited due to a lack of PM monitoring stations. Since visual range (VR) is proportional to particle light extinction, VR can serve as a surrogate for PM_2.5 (particulate matter with an aerodynamic diameter ≤2.5 µm) concentrations. We used data on VR, relative humidity (RH), and PM_2.5 ground measurements collected in Kuwait from years 2004-2005 to establish the relationship between PM_2.5 and VR. Model validation obtained by regressing trimester average PM_2.5 predictions against PM_2.5 measurements in Kuwait produced an r² value of 0.84. Cross validation of urban and rural sites in Kuwait also revealed good model fit. We applied this relationship to location-specific visibility data at 104 regional sites between years 2000-2012 to estimate monthly average PM_2.5 concentrations. Monthly averages at sites in Iraq, Afghanistan, United Arab Emirates, Kuwait, Djibouti, and Qatar ranged from 10 to 365 µg/m3 during this period, while site averages ranged from 22 to 80 µg/m3, indicating considerable spatial and temporal heterogeneity in ambient PM_2.5 across these regions. These data support the use of historical visibility data to estimate location-specific PM_2.5 concentrations for application in epidemiological studies.

IMPLICATIONS

This study demonstrates the ability to use airport visibility to estimate PM_2.5 concentrations in Southwest Asian and Afghanistan. This supports the use of historical and ongoing visibility data to estimate PM_2.5 exposure in this region of the world, where PM exposure information is otherwise scarce. This is of high utility to epidemiologists investigating the relationship between chronic exposure to PM_2.5 and respiratory diseases among deployed military personnel stationed at various military bases throughout the region. Such information will enable the drafting of improved policies relating to military health.

Review of Particulate Matter and Elemental Composition of Aerosols at Selected Locations in Nigeria from 1985-2015

BACKGROUND

Over the past 30 years, various studies in Nigeria have monitored atmospheric particulate matter loads and elemental composition of ambient air around diverse receptor sites.

OBJECTIVES

A comparative discussion of the different sampling techniques, pre-treatment and analytical methods employed between 1985 and 2015.

METHODS

Air pollution indices from studies covered in this review were compared to relevant guideline standards such as the World Health Organization (WHO) 24-hr guideline and the United States Environmental Protection Agency (USEPA)'s National Ambient Air Quality Standard (NAAQS) daily permissible limits for fine particles of less than 2.5 micrometers in diameter (PM2.5) and coarse dust particles with a diameter of 10 micrometers (PM10) in ambient air. In addition, the sources of data for the average concentrations for PM2.5, PM10 and related metallic elements during 1985-2015 were assessed. Attempts were also made to compare varied particulate matter loads of atmospheric micro-environments in Nigeria with comparable micro-environments in selected cities around the world.

DISCUSSION

Results showed that PM2.5 concentration ranged from 5-248 μg/m3, while PM10 concentration ranged from 18-926 μg/m3, revealing that about 50% of the particulate matter loads in Nigeria exceeded both the WHO (25 μg/m3, 50 μg/m3) and NAAQS (35 μg/m3, 150 μg/m3) guideline limits for PM2.5 and PM10 respectively. PM2.5/PM10 ratios for the selected studies fall below the WHO guideline (0.5-0.8), suggesting that Nigerian aerosols are mainly made up of coarse, rather than fine particles. In addition, the order of the average highest concentrations of metallic elements for PM2.5 were magnesium (Mg) > strontium (Sr) > potassium (K) > zinc (Zn) > iron (Fe) > sodium (Na) > aluminium (Al) > chlorine (Cl) > lead (Pb) > silicon (Si), while those of PM10 were Sr > Zn > Fe > Mg > calcium (Ca) >Na > Pb > manganese (Mn) > K > Al.

CONCLUSIONS

Seasonal variation of particulate matter loads revealed higher concentrations during the dry season than during the rainy season. In addition, particulate matter loads in rural areas were generally lower than in urban areas. Wind-blown dust from the Sahara Desert is the major contributor to particulate matter loads in northern zones of the country, while sea spray and crustal matter are the highest contributors to particulate matter loads in southern zones.