The relative contributions of traffic and non-traffic sources in ultrafine particle formations in Tehran mega city.

Emissions of ultrafine particles (UFPs; diameter < 100 nm) are strongly associated with traffic-related emissions and are a growing global concern in urban environments. The aim of this study was to investigate the variations of particle number concentration (PNC) with a diameter > 10 nm at nine stations and understand the major sources of UFPs (primary vs. secondary) in Tehran megacity. The study was carried out in Tehran in 2020. NOx and PNC were reported from a total of nine urban site locations in Tehran and BC concentrations were examined at two monitoring stations. Data from all stations showed diurnal changes with peak morning and evening rush hours. The hourly PNC was correlated with NOx. PNCs in Tehran were higher compared to those of many cities reported in the literature. The highest concentrations were at District 19 station (traffic) and the lowest was at Punak station (residential) such that the average PNC varied from 8.4 × 103 to 5.7 × 104 cm-3. In Ray and Sharif stations, the average contributions of primary and secondary sources of PNC were 67 and 33%, respectively. Overall, we conclude that a decrease in primary emission leads to a decrease in the total concentration of aerosols, despite an increase in the formation of new particles by photo nucleation.

Heterogeneous (gas-solid) chemistry of atmospheric Cr: A case study of Astana, Kazakhstan.

Hexavalent chromium (Cr(VI)) is a known carcinogen derived from both anthropogenic and natural sources. This work reports the size-segregated concentrations of total Cr(VI) in particulate matter (PM) in Astana, the capital of Kazakhstan, and provides new insights into the gas-solid reactions of atmospheric Cr. A study of total Cr(VI) in the particulate matter, via a microwave-assisted digestion technique, was conducted using a 5-stage Sioutas Cascade impactor that captures airborne particles in size ranges: >2.5 µm, 1.0-2.5 µm, 0.50-1.0 µm, 0.25-0.50 µm, and <0.25 µm. The total Cr(VI) concentration in the size fraction <0.25 µm was the highest with a maximum value of 9.7 ng/m3. This high concentration may pose a greater risk because smaller airborne particles can penetrate deeper into the lower respiratory tract of the lungs. Total suspended particles Cr(VI) exceeded the 8.0 ng/m3 Reference Concentration (RfC) by 22 times. The overall total Cr(VI) concentration in summer was significantly higher than in fall (p < 0.05), which could be due to factors, including higher temperatures, ozone, and NO2 concentrations in summer and a higher VOC concentration in fall. The results indicate that the interaction between Cr(III) and Cr(VI) through gas-solid reaction can control the speciation of atmospheric Cr.

Effect of carbonaceous ultrafine particles on the structure and oligomerization of Aß42 peptide.

The impact of pervasive air pollutants on human health is a growing concern in scientific communities. Among different air pollutants, ultrafine particles (UFPs; with aerodynamic diameter <100 nm) might pass through biological barriers and have a severe impact on human health, including early progression of neurodegenerative diseases such as Alzheimer's disease (AD). A significant fraction of UFPs consists of carbonaceous compounds, composed of elemental and organic carbon (EC and OC). While in-vivo experimental studies showed the neurotoxicity of typical OC and polycyclic aromatic hydrocarbons (PAHs), the molecular interactions involved in the progression of AD remain unclear. In this study, molecular dynamics simulations were performed to investigate the impact of carbonaceous UFPs on the structure of the Aß42 monomer and the oligomerization of four Aß42 peptides, associated with the development of AD. For the simulations, a fullerene (C60) was used for the modeling of EC, while benzo [a]pyrene (B[a]P) was used for the modeling of OC. The results revealed that the presence of C60 accelerated the tetramerization of Aß42 peptides by 2.5 times, while C60/B[a]P promoted the unfolding of the peptide monomer showing the strongest interactions with the Aß42 monomer. Similarly, C60/4B[a]P decreased the number of helices in the secondary structure of the peptide monomer by 60%. The simplified UFP models in this study, promoted the early aggregation of peptides to dimers, suggesting the progression of AD.

N,Zn-Doped Fluorescent Sensor Based on Carbon Dots for the Subnanomolar Detection of Soluble Cr(VI) Ions.

The development of a fluorescent sensor has attracted much attention for the detection of various toxic pollutants in the environment. In this work, fluorescent carbon dots (N,Zn-CDs) doped with nitrogen and zinc were synthesized using citric acid monohydrate and 4-pyridinecarboxyaldehyde as carbon and nitrogen sources, respectively. The synthesized N,Zn-CDs served as an "off" fluorescence detector for the rapid and sensitive detection of hexavalent chromium ions (Cr(VI)). The zinc metal integrated into the heteroatomic fluorescent carbon dot played a functional role by creating a coordination site for the hydrogen ions that were displaced after the addition of Cr to the solution matrix. The stepwise addition of Cr(VI) effectively quenched the fluorescence intensity of the N,Zn-CDs, and this phenomenon was attributed to the internal filter effect. A low detection limit of 0.47 nmol/L for Cr(VI) was achieved in the fluorescence experiments. Real water samples were used to evaluate the practical application of N,Zn-CDs for the quantification of Cr(VI). The results show acceptable recoveries and agreement with ion chromatography-ultraviolet spectrometry results. These good recoveries indicate that the fluorescence probe is very well suited for environmental measurements.

A review of critical residential buildings parameters and activities when investigating indoor air quality and pollutants.

Indoor air in residential dwellings can contain a variety of chemicals, sometimes present at concentrations or in combinations which can have a negative impact on human health. Indoor Air Quality (IAQ) surveys are often required to characterize human exposure or to investigate IAQ concerns and complaints. Such surveys should include sufficient contextual information to elucidate sources, pathways, and the magnitude of exposures. The aim of this review was to investigate and describe the parameters that affect IAQ in residential dwellings: building location, layout, and ventilation, finishing materials, occupant activities, and occupant demography. About 180 peer-reviewed articles, published from 01/2013 to 09/2021 (plus some important earlier publications), were reviewed. The importance of the building parameters largely depends on the study objectives and whether the focus is on a specific pollutant or to assess health risk. When considering classical pollutants such as particulate matter (PM) or volatile organic compounds (VOCs), the building parameters can have a significant impact on IAQ, and detailed information of these parameters needs to be reported in each study. Research gaps and suggestions for the future studies together with recommendation of where measurements should be done are also provided.

Quantification and the sources identification of total and insoluble hexavalent chromium in ambient PM: A case study of Aktobe, Kazakhstan.

Hexavalent chromium (Cr(VI)), a known carcinogen, emanates from both anthropogenic and natural sources. A pilot study of the ambient Cr(VI) concentrations was conducted at the center of Aktobe which is a few kilometers away from major industrial chromium plants. Total Cr(VI) concentrations were measured in the fall and winter seasons with mean values (S.D) of 5.30 (2.16) ng/m3 and 2.26 (1.80) ng/m3, respectively. Insoluble Cr(VI) levels were 4.80 (1.96) and 2.19 (1.75) ng/m3 for the fall and winter, respectively. The total and insoluble Cr(VI) concentrations in the fall season were significantly higher than in winter, likely due to the higher rate of Cr(III) oxidation in the presence of ozone and ROS in fall compared to the rate of Cr(VI) reduction in the presence of VOCs at higher temperatures. On average, total Cr(VI) constituted 34.49% of the total Cr concentrations suggesting that the dominant valence state of Cr in the atmosphere is Cr(III). The previous reference values of exposure to Cr(VI) must be revisited by taking into account the insoluble Cr(VI) concentration since it is more prevalent in the atmosphere compared to soluble Cr(VI). The influence of the chromium plants as potential sources was not obvious in this study.

Human exposure to aerosol from indoor gas stove cooking and the resulting nervous system responses.

Our knowledge of the effects of exposure to indoor ultrafine particles (sub-100 nm, #/cm3 ) on human brain activity is very limited. The effects of cooking ultrafine particles (UFP) on healthy adults were assessed using an electroencephalograph (EEGs) for brain response. Peak ultrafine particle concentrations were approximately 3 × 105 particle/cm3, and the average level was 1.64 × 105 particle/cm3 . The average particle number emission rate (S) and the average number decay rate (a+k) for chicken frying in brain experiments were calculated to be 2.82 × 1012 (SD = 1.83 × 1012 , R2  = 0.91, p = 0.0013) particles/min, 0.47 (SD = 0.30, R2  = 0.90, p < 0.0001) min-1 , respectively. EEGs were recorded before and during cooking (14 min) and 30 min after the cooking sessions. The brain fast-wave band (beta) decreased during exposure, similar to people with neurodegenerative diseases. It subsequently increased to its pre-exposure condition for 70% of the study participants after 30 min. The brain slow-wave band to fast-wave band ratio (theta/beta ratio) increased during and after exposure, similar to observed behavior in early-stage Alzheimer's disease (AD) patients. The brain then tended to return to its normal condition within 30 min following the exposure. This study suggests that chronically exposed people to high concentrations of cooking aerosol might progress toward AD.

Formation of cluster mode particles (1-3 nm) in preschools.

This study is the first study that reports the cluster particle (1-3 nm) formation (CPF) in two modern preschools located in Nur-Sultan city of Kazakhstan from October 28 to November 27, 2019. The average particle number concentration and mode diameter values during major CPF events in Preschool I and Preschool II were found to be 1.90 × 106 (SD 6.43 × 106) particles/cm3 and 1.60 (SD 0.85) nm, and 1.11 × 109 (SD 5.46 × 109) particles/cm3 and 2.16 (SD 1.47) nm, respectively. The ultraviolet PM concentration reached as high as 7 µg/m3 in one of the measurement days. The estimated emission rate in Preschool I for CPF events was 9.57 × 109 (SD 1.92 × 109) particles/min. For Preschool II, the emission rate was 7.25 × 109 (SD 12.4 × 109) particles/min. We identified primary cluster particles (CPs) emitted directly from the sources such as candle burning, and secondary CPs formed as a result of the oxidation of indoor VOCs or smoking VOCs. The secondary CPs are likely to be SOA. Indoor VOCs were mainly emitted during cleaning activities as well as during painting and gluing. Indoor VOCs are the controlling factors in the CPF events. Changes in the training and cleaning programs may result in significant reductions in the exposure of the children to CPs.

The state of science on severe air pollution episodes: Quantitative and qualitative analysis.

Severe episodic air pollution blankets entire cities and regions and have a profound impact on humans and their activities. We compiled daily fine particle (PM2.5) data from 100 cities in five continents, investigated the trends of number, frequency, and duration of pollution episodes, and compared these with the baseline trend in air pollution. We showed that the factors contributing to these events are complex; however, long-term measures to abate emissions from all anthropogenic sources at all times is also the most efficient way to reduce the occurrence of severe air pollution events. In the short term, accurate forecasting systems of such events based on the meteorological conditions favouring their occurrence, together with effective emergency mitigation of anthropogenic sources, may lessen their magnitude and/or duration. However, there is no clear way of preventing events caused by natural sources affected by climate change, such as wildfires and desert dust outbreaks.

Exposure to fine, ultrafine particles and black carbon in two preschools in nur-sultan city of kazakhstan.

Children in preschools were studied as an exceptionally vulnerable group to lung diseases due to their immature immune system. Few data are available in the literature addressing the exposure of children in preschools to ultrafine (>10 nm) particles. Exposure of children to fine, ultrafine (10 nm-1 µm) particles and black carbon particles present inside and near two preschools in Nur-Sultan, Kazakhstan, during Fall 2019 was investigated. For Preschool I, the average daily (6 h) indoor (outdoor) PM1 , PM2.5 , and PM10 concentrations over three-week measurements were 15.0 (SD 12.5) µg/m3 , 34.6 (SD 35.1) µg/m3 , and 47.2 (SD 45.2) µg/m3 , respectively. Average indoor UFP concentrations (>10.0 nm) including candle burning events were 5.20 × 103 (SD 8.80 × 103 ) particles/cm3 , with the background UFP concentration to be 3.30 × 103 (SD 1.80 × 103 ) particles/cm3 . In Preschool II, the average UFP concentration (>30.0 nm) in the morning and afternoon was 3.94 × 103 (SD 5.34 × 102 ) and 3.36 × 103 (SD 1.90 × 103 ) particles/cm3 , respectively. Indoor black carbon (BC) concentrations were correlated with the outdoor smoking activity. The major sources of the indoor particles in the preschools were dust resuspension, candle burning, and infiltrated outdoor particles.

Suspended fine particulate matter (PM2.5), microplastics (MPs), and polycyclic aromatic hydrocarbons (PAHs) in air: Their possible relationships and health implications.

Exposure to fine particulate matter (PM2.5) and their associated microcontaminants have been linked to increased harmful effects on the human health. In this study, the possible relationships between PM2.5, microplastics (MPs), and polycyclic aromatic hydrocarbons (PAHs) were analyzed in an urban area of Bushehr port, in the northern part of the Persian Gulf. Presence, sources, and health risks of MPs and PAHs in both normal and dusty days were also investigated. The median of PM2.5 and Æ©PAHs were 52.8 µg/m3 and 14.1 ng/m3, respectively, indicating high pollution levels especially in dusty days. The mean level of MPs in urban suspended PM2.5 was 5.2 items/m3. Fragments were the most abundant shape of identified MPs and polyethylene terephthalate (PET) was the most plastic types in urban dust of Bushehr port. The results revealed that PM2.5 and MPs may possibly act as a carrier for airborne MPs and PAHs, respectively. In addition, the significant positive relationships between MPs, wind speed and wind direction, confirmed that the MPs transportation were highly controlled by atmospheric condition. Moreover, the source identification methods and trajectory analyses indicated that petrogenic sources from both proximal and distal origins play an important role in the level of PAHs. The results of chronic health risk evaluation via inhalation revealed that PM2.5-bound PAHs had high potential cancer risk in winter, while, the estimated risks for non-carcinogenic PAHs were not considerable. In the case of MPs, the assessment of human intake of MPs via inhalation highlighted the possible risks for habitants.

The impact on heart rate and blood pressure following exposure to ultrafine particles from cooking using an electric stove.

Cooking is a major source of indoor particulate matter (PM), especially ultrafine particles (UFPs). Long-term exposure to fine and ultrafine particles (UFPs) has been associated with adverse human health effects. Toxicological studies have demonstrated that exposure to PM2.5 (particles with aerodynamic diameter smaller than 2.5 µm) may result in increased blood pressure (BP). Some clinical studies have shown that acute exposure to PM2.5 causes changes in systolic (SBP) and diastolic blood pressure (DBP), depending on the source of particles. Studies assessing the effect of exposure to cooking PM on BP and heart rate (HR) using electric or gas stoves are not well represented in the literature. The aim of this investigation was to perform controlled studies to quantify the exposure of 50 healthy volunteer participants to fine and ultrafine particles emitted from a low-emissions recipe for frying ground beef on an electric stove. The BP and heart rate (HR) of the volunteers were monitored during exposure and after the exposure (2 h post-exposure). Maximum UFP and PM2.5 concentrations were 6.5 × 104 particles/cm3 and 0.017 mg/m3, respectively. Exposure to UFPs from frying was associated with statistically significant increases in the SBP. The lack of food and drink during the 2 h post-cooking period was also associated with a statistically significant reduction in SBP. No statistically significant changes in DBP were observed. Physiological factors, including heat stress over the stove, movements and anxiety, could be responsible for an elevation in HR at the early stages of the experiments with a subsequent drop in HR after 90 min post-cooking, when study participants were relaxed in a living room.

Zinc metal-organic framework with 3-pyridinecarboxaldehyde and trimesic acid as co-ligands for selective detection of Cr (VI) ions in aqueous solution.

There is an increasing need for the development of probes for the detection of hexavalent chromium since it is a known carcinogen, which can cause adverse effects on human health. Metal-organic frameworks (MOFs) have shown successful detection and removal of hazardous substances from aqueous media. This work presents the use of simple organic ligands such as 3-pyridinecarboxaldehyde and trimesic acid with Zn(II) ion to fabricate a new MOF that exhibits sensitive and selective luminescence quenching response towards CrO4 2- and Cr2O7 2- species in aqueous solution. The MOF showed a detection limit of 0.67 µM (0.078 ppm) as CrO4 2- species and 1.91 µM (0.41 ppm) as Cr2O7 2- species. Results reveal that the as-synthesized MOF could serve as a good luminescent sensor for CrO4 2- and Cr2O7 2- species in the contaminated aqueous phase.

Impact of volatile organic compounds on chromium containing atmospheric particulate: insights from molecular dynamics simulations.

The effect of volatile organic compounds (VOCs) on chromium-containing atmospheric particles remains obscured because of difficulties in experimental measurements. Moreover, several ambiguities exist in the literature related to accurate measurements of atmospheric chromium concentration to evaluate its toxicity. We investigated the interaction energies and diffusivity for several VOCs in chromium (III)-containing atmospheric particles using classical molecular dynamics simulations. We analyzed xylene, toluene, ascorbic acid, carbon tetrachloride, styrene, methyl ethyl ketone, naphthalene, and anthracene in Cr(III) solutions, with and without air, to compare their effects on solution chemistry. The interaction energy between Cr(III) and water changed from 48 to 180% for different VOCs, with the highest change with anthracene and the lowest change with naphthalene. The results revealed no direct interactions between Cr(III) particles and the analyzed volatile organic compounds, except ascorbic acid. Interactions of Cr(III) and ascorbic acid differ significantly between the solution phase and the particulate phase. The diffusion of Cr(III) and all the VOCs also were observed in a similar order of magnitude (~ 10-5 cm2/s). The results can further assist in exploring the variation in chromium chemistry and reaction rates in the atmospheric particles in the presence of VOCs.

SO2 and HCHO over the major cities of Kazakhstan from 2005 to 2016: influence of political, economic and industrial changes.

Satellite observations of the Ozone Monitoring Instrument (OMI) for tropospheric sulfur dioxide (SO2) and formaldehyde (HCHO) column mass densities (CMD) are analyzed for the period 2005-2016 over the atmosphere of Kazakhstan. Regarding SO2 the major hot spots relate to regions with high population and large industrial facilities. Such an example is the city of Ekibastuz that hosts the biggest thermal power plants in the country and exhibits the higher SO2 CMD at national level. The annual average CMD in Ekibastuz reaches 2.5 × 10-5 kg/m2, whereas for the rest of the country respective values are 6 times lower. Other hotspots, mostly urban conglomerates such as Almaty and Nur-Sultan, experience high CMDs of SO2 in particular years, such as 2008. One of the main reasons for this behavior is the financial crisis of 2008, forcing the application of alternate heating sources based on cheap low-quality coal. Regarding HCHO, an oxygenated Volatile Organic Compound (VOC), the main hot spot is noticed over the city Atyrau, the oil capital of the country where two massive oil fields are located. The highest HCHO CMD (9 × 1015 molecules/cm2) appears in the summertime due to secondary production as a result of the photo-oxidation of VOCs emitted by industrial sectors, oil refinery plants and vehicles. Strongly elevated HCHO amounts are also observed in Nur-Sultan in 2012 that could be due to the residential coal combustion and vehicle exhaust under poor winter dispersion conditions. Significant reductions in HCHO observed between 2012 and 2015 can be attributed to two significant measures implemented in the country in 2013 that aimed at the improvement of air quality: the introduction of the emission trading system (ETS) for greenhouse gases and Euro-4 standards for new vehicles entering the national vehicle fleet.

A new exposure route to trace elements in indoor particulate matter.

Concentrations and emission rates of sixteen trace elements in emitted PM during heating soybean oil using three types of pans, including Teflon, granitium, and cast-iron, were investigated. Statistically significant decreases in Mn and Co emission rates were observed when the oil was heated in the cast-iron pan compared to Teflon and granitium pans. Among the released trace elements, Ni, Ba, Zn, and Cr had more contribution to the emission rate. The concentrations of Fe in the emitted PM1 were found to be higher when cast-iron pan (8.49 ± 3.35 µg/m3 ) was utilized compared to Teflon (8.05 ± 2.27 µg/m3 ) and granitium (7.45 ± 1.38 µg/m3 ). However, these increases were statistically insignificant. The results of our study support the hypothesis that the trace elements translocate from cooking pans into the heated oil and subsequently to the particulate phase. This translocation creates a new inhalation exposure route to trace elements in indoor environments.

The impact of frying aerosol on human brain activity.

Knowledge on the impact of the exposure to indoor ultrafine particles (UFPs) on the human brain is restricted. Twelve non-atopic, non-smoking, and healthy adults (10 female and 7 male, in average 22 years old) were monitored for brain physiological responses via electroencephalographs (EEGs) during cooking. Frying ground beef meat in sunflower oil using electric stove without ventilation was conducted. UFPs, particulate matter (PM) (PM1, PM2.5, PM4, PM10), CO2, indoor temperature, RH, oil and meat temperatures were monitored continuously throughout the experiments. The UFP peak concentration was recorded to be approximately 2.0 × 105 particles/cm3. EEGs were recorded before exposure, at end of cooking when PM peak concentrations were observed, and 30 min after the end of the cooking session (post-exposure). Brain electrical activity statistically significantly changed during post-exposure compared to the before exposure, suggesting the translocation of UFPs to the brain, occurring solely in the frontal and temporal lobes of the brain. Study participants older than 25 were more susceptible to UFPs compared to those younger than 25. Also, the brain abnormality was mainly driven by male rather than female study participants. The brain slow-wave band (delta) decreased while the fast-wave band (Beta3) increased similar to the pattern found in the literature for the exposure to smoking fumes and diesel exhaust.

Contributions of burner, pan, meat and salt to PM emission during grilling.

Grilling ground beef meat was conducted in two locations at Nazarbayev University, Kazakhstan. The experiments were designed such that only particles from beef meat were isolated. A similar experimental protocol was applied at both locations. The average particle number and mass emission rates for grilling pure meat itself (excluding particles from pan and burner) were found to be 9.4 × 1012(SD = 7.2 × 1012 particle min-1 and 7.6 × 10 (SD = 6.3 × 10) mg.min-1, respectively. The PM emissions (number and mass) from the burner were found to be negligible compared to the pan and meat emissions. Ultrafine particle (UFP) concentrations from the heated pan itself were comparable to those of grilled meat. However, the particle mass concentrations from the pan itself were negligible. Approximately an hour of continuous heating resulted in zero emissions from the pan.

Investigating the impact of different sport trainings on particulate matter resuspension in a sport center using well-characterized reference instruments and a low-cost monitor.

The present study investigated the exposure of teenagers, adults, and students to PM1, PM2.5, PM4, PM10, particle number concentration at two sport facilities of Nazarbayev University including Gymnastics Hall and Multi-purpose Hall. Measurements were conducted during variety of sport training sessions including soccer, basketball, volleyball, Mixed Martial Arts (MMA), boxing, table tennis, etc. A low-cost instrument, Dylos was employed to compare its performance against two TSI instruments. In overall, the Dylos showed acceptable peaks when the source of particle resuspension was present. However, no correlation was observed between Dylos data and Dusttrak fine and coarse particle data. The average PM2,5 and PM10 concentrations were found to be below the WHO limits. The number of participants during the training sessions and sports involving balls including basketball, soccer and volleyball were the two factors responsible for the observed increased particle resuspension.

Quantifying trace elements in the emitted particulate matter during cooking and health risk assessment.

Particulate matter (PM) measurements were conducted during heating corn oil, heating corn oil mixed with the table salt and heating low fat ground beef meat using a PTFE-coated aluminum pan on an electric stove with low ventilation. The main objectives of this study were to measure the size segregated mass concentrations, emission rates, and fluxes of 24 trace elements emitted during heating cooking oil or oil with salt and cooking meat. Health risk assessments were performed based on the resulting exposure to trace elements from such cooking activities. The most abundant elements (significantly different from zero) were Ba (24.4 ug m-3) during grilling meat and Ti during heating oil with salt (24.4 ug m-3). The health assessment indicates that the cooking with an electric stove with poor ventilation leading to chronic exposures may pose the risk of significant adverse health effects. Carcinogenic risk exceeded the acceptable level (target cancer risk 1 × 10-6, US EPA 2015) by four orders of magnitude, while non-carcinogenic risk exceeded the safe level (target HQ = 1, US EPA 2015) by a factor of 5-20. Cr and Co were the primary contributors to the highest carcinogenic and non-carcinogenic risks, respectively.