Air Concentrations Research Articles

Investigation of Formaldehyde Concentration in Indoor and Outdoor Air, A Systematic Review

Formaldehyde, commonly recognized as formalin, stands as the archetypal aldehyde, distinguished by its colorless gaseous form and acrid scent. Widespread usage and dissemination of this compound pose potential risks of dermatological and ocular irritation, respiratory ailments, genetic alterations, and carcinogenesis. This study aims to explore the concentrations of formaldehyde in both indoor and outdoor environments. The search strategy involved querying English-language articles in Google Scholar and Science Direct databases, specifically selecting those detailing formaldehyde concentrations. Ultimately, 16 articles meeting the criteria were included in the study. Results reveal that outdoor formaldehyde mean concentration reached up to 17.02 ± 11.46 ppm, while indoor level was 0.528 ± 0.527 ppm. Industrial settings exhibited the highest concentrations, with a mean of 10.73 ± 4.5 ppm. The study exposes higher formaldehyde levels in Asian countries (0.0522 ± 0.075 ppm) compared to European and North American counterparts. Additionally, concentrations displayed a tendency to rise during the summer (3.57 ± 5.03 ppm) in contrast to the winter season (3.08 ± 5.03 ppm). These findings underscore the need for heightened awareness and regulatory measures to mitigate formaldehyde exposure, especially in industrial contexts and regions with elevated concentrations.

Evaluation of the performance of bituminous geomembranes (BGMs) as vapour barriers

Vapour barriers (VBs) are essential in maintaining the indoor air quality of home basements or industrial facilities, especially when subsurface contamination poses a risk to human health. It is of utmost importance that the material installed as VB has the capacity to prevent contaminant migration into the indoor air space and reduce its concentration to an acceptable limit. Bituminous geomembranes (BGMs) have been used as contaminant barriers in spite of the gap in research regarding the permeation of volatile organic compounds (VOCs) through BGMs. This study examines the performance of a 4.1mm thick elastomeric BGM as a diffusive barrier to four commonly found VOCs; benzene, toluene, ethylbenzene, and xylenes (BTEX), utilizing computer modelling of contaminant migration from a contaminated soil source to a hypothetical warehouse building constructed on a brownfield site. The effectiveness of BGM in preventing vapour intrusion is evaluated based on its capacity to keep the indoor air concentration of the contaminant below the recommended exposure limits (RELs). Based on the modelling results, the BGM can be expected to perform as a very efficient VB for the simulated warehouse if quality control can be ensured during installation. This modelling approach can be adopted to investigate BGMs’ performance in different remediated site scenarios to make scope for a robust decision-making process regarding the construction and the engineering control requirements.

Modeling of PM concentrations on a construction site based on IoT monitoring system

An IoT-based system framework integrating a distributed sensor network was implemented to collect real-time data at a construction site. Various sensors were utilized to gather data concerning particulate matter (PM2.5 and PM10 concentrations) as well as meteorological parameters - wind speed, humidity, pressure, and temperature. The real-time measurements results provide an overview of air pollution levels at the construction site, revealing its association with earth excavation work, the primary construction activity. This connection allows for better management aimed at reducing concentrations of suspended particles. Through on-site monitoring of two pollutant concentrations, this study identified that the dust levels resulting from excavation activities were relatively high. It can be concluded that earth excavation significantly impacts air quality in the construction area. While exploring the primary factors influencing construction dust concentrations, the correlations indicate that these concentrations were not significantly associated with meteorological factors. To predict PM2.5 and PM10 concentrations in the air using number of working machines and meteorological parameters as predictors, both Multiple linear regression (MLR) and Artificial Neural Network (ANN) models were applied. The ANN model demonstrates better alignment with the measured air concentrations compared to the MLR model. The ANN model demonstrated an R-squared value of 0.674 for PM10 and 0.618 for PM2.5, indicating a strong predictive capability. The aim of this research, through modeling PM2.5 and PM10 concentrations in the air at the construction site is to indicate importance of the topic, especially with respect to the health of the constuction site workers.

“Visibility” at Italian natural parks: preliminary data from the first-ever pilot project by ENEA and CUFAA

“Visibility” is meant as the greatest distance at which an observer can see a distant object in contrast with the horizon and, when referred to a landscape, it depends on the optical characteristics of the atmosphere, somehow linked to the presence of air pollutants. Visibility can hence become a useful indicator of air quality and the project Visibility, representing the first case of visibility monitoring in Europe, aims to apply this approach within the Italian National Parks as natural areas with a significant fruition vocation. The goal is to test the U.S. National Park Service protocol I.M.PRO.V.E. (Interagency Monitoring of PROtected Visual Environment) for the quantification of a coefficient that describes the light extinction (Bext) as a function of different chemical-physical parameters associated with molecules dispersed in the air, and the Circeo National Park (LT) was selected for the “pilot” action, with the positioning of the measuring instruments for atmospheric pollution evaluation at the Lago dei Monaci site. 24-hours samplings were performed in spring-summer 2021 and winter 2021/2022, to measure the air concentration of PM2.5 and PM10 particulate matter, sulfates and nitrates, elemental carbon and organic carbon, metals and trace elements and the gaseous species nitrogen dioxide, with the consequential calculation of the Bext. The visual detection of the degree of air transparency was performed by a panoramic camera pointed in the direction of the “landmark” Monte Circeo, taken as a reference for the definition of long-distance visibility.

The chemical assessment of surfaces and air (CASA) study: using chemical and physical perturbations in a test house to investigate indoor processes.

The Chemical Assessment of Surfaces and Air (CASA) study aimed to understand how chemicals transform in the indoor environment using perturbations (e.g., cooking, cleaning) or additions of indoor and outdoor pollutants in a well-controlled test house. Chemical additions ranged from individual compounds (e.g., gaseous ammonia or ozone) to more complex mixtures (e.g., a wildfire smoke proxy and a commercial pesticide). Physical perturbations included varying temperature, ventilation rates, and relative humidity. The objectives for CASA included understanding (i) how outdoor air pollution impacts indoor air chemistry, (ii) how wildfire smoke transports and transforms indoors, (iii) how gases and particles interact with building surfaces, and (iv) how indoor environmental conditions impact indoor chemistry. Further, the combined measurements under unperturbed and experimental conditions enable investigation of mitigation strategies following outdoor and indoor air pollution events. A comprehensive suite of instruments measured different chemical components in the gas, particle, and surface phases throughout the study. We provide an overview of the test house, instrumentation, experimental design, and initial observations - including the role of humidity in controlling the air concentrations of many semi-volatile organic compounds, the potential for ozone to generate indoor nitrogen pentoxide (N2O5), the differences in microbial composition between the test house and other occupied buildings, and the complexity of deposited particles and gases on different indoor surfaces.

Finding the conditions of optimal combustion mode of liquid fuel atomized by superheated steam through of regime map analysis

The problem of development of an algorithm for searching the conditions of the optimal combustion mode on the example of experimental data of combustion of diesel fuel atomized by superheated steam is considered. Approximated regime maps were used as an analysis tool. The optimal combustion mode was chosen as an average between two components: the equation of minimum carbon monoxide concentrations, which provides combustion with minimum concentrations of harmful substances in the combustion products; and the equation of the lower line of maximum values on the gradient surface of carbon monoxide concentrations, which provides high efficiency of the burner device operation compared to the zone of optimal combustion due to lower air concentrations.

Tritium uptake in crops in the area with a high level of atmospheric tritium oxide in the territory of the former Semipalatinsk test site.

During the period from 2019 to 2021, a series of experiments were carried out to study the uptake of tritium by crops in an area heavily contaminated with atmospheric tritium oxide (HTO), at the former Semipalatinsk test site in Kazakhstan. A quantitative assessment is given of the tritium uptake by typical crops (lettuce, tomatoes, peppers and beans) cultivated all over Kazakhstan in the case of a short-term tritium oxide vapor exposure. The plant samples were collected during and after exposure and analyzed for the tritium concentration in two chemical forms: tissue-free water tritium (TFWT) and organically bound tritium (OBT). During the entire series of experiments, the tritium concentration in free water from leaves and ambient air was of the same order of magnitude. The tissue water tritium concentrations of stems and edible parts was 1 to 2 orders of magnitude lower than in the surrounding air. The average value of the TFWT/HTOatm ratio in the leaves and the edible part was (0.73±0.2) and (0.04±0.002), respectively. The organically-bound tritium concentration is 1-2 orders of magnitude lower than the tissue water tritium and ambient air concentrations. Under aerial tritium oxide uptake, the distribution of tritium in non-leafy crops was as follows: leaf-stem-fruit (in decreasing order). After exposure, a non-significant amount of tritium is firmly retained in plants for a long time. The tissue water tritium concentrations correlate closely with atmospheric tritium oxid (r = 0.76), correlate weakly with temperature (r = 0.43) and relative humidity (r = -0.43), and correlate moderately with solar radiation intensity (r = 0.56). There was no reliable correlation between the concentration of tritium in organic matter and in ambient air. The concentration of tritium in the free water of leaves is closely correlated with the concentration in the free water of the stems (r = 0.95) and fruits (r = 0.78). The organically-bound tritium concentration in leaves is closely correlated with the organically-bound tritium concentration in stems (r = 0.99) and fruits (r = 98). The results of the study should be considered when evaluating the impact of tritium oxide emissions on the population living near nuclear power.

Numerical simulation and experimental application of a 300 MW boiler combustion system

In the actual operation of a 300 MW boiler, there are some problems such as unstable combustion, high combustible material of fly ash and slag, and large thermal deviation on both sides of steam. The Cooper method is used to divide the three parts of the furnace by a hexahedral structured grid, which can reduce the grid number and improve the numerical simulation calculation precision. The Realization k-ε turbulent model is used to simulate the gas-solid two-phase flow in the furnace before and after reconstruction. The boundary of the calculation model adopts the actual operating parameters, and the numerical calculation adopts the three-dimensional steady-state calculation - Simple algorithm. The conclusions are as follows: the amount of pulverized coal powder falling into the cold ash hopper is reduced from 0.077 kg/m3 before the reconstruction to 0.045 kg/m3 after the reconstruction, with a decrease of about 42%. The secondary air concentration arrangement in the lowest two layers strengthened the secondary air supporting capacity. The residence time of pulverized coal particles in the furnace is increased from 30.59 s before the reconstruction to 39.97 s after the reconstruction, and the time is extended by about 9.4 s, which is beneficial to the combustion of pulverized coal particles. The centralized arrangement of primary air in the lowest two layers is beneficial to the initial ignition and stable combustion of pulverized coal gas. The downdip of the tertiary air incidence angle reduces the rotational momentum of the tertiary airflow, and the increase of the rotational momentum of the over-fire air angle is conducive to weakening the residual rotation at the furnace outlet. After the implementation of the reconstruction measures, the boiler can be stably burned at 150 MW, the combustible material of fly ash and slag are reduced to the controllable range, the steam thermal deviation is significantly reduced, and the boiler operating parameters are stable.

The effect of human activities on Bali’s Silent Day (Nyepi) in 2022

During Nyepi, all activities are eliminated, including public services, such as closing access to land, sea, and air transportation routes that transit to Bali for one day. In 2022, the BMKG Research and Development Center observed air quality in Nyepi. The measurement aims to determine the relative reduction level of greenhouse gas (GHG) and particulate emissions on Nyepi Day compared to before and after. Greenhouse gases and particulates were measured for seven days, February 28 - March 6, 2022. The measurement locations were over 3 points: Denpasar Regional Office III, Karangasem Geophysics Post, and Jembrana Climatology Station. The results of this field measurement show that daily human activities significantly influence the concentration of pollutant gases and particulates in the air. During Nyepi Day, air concentration improves when all human actions are reduced. This is marked by a decrease in the air’s concentration of pollutant gases (CO, NO2) and dust particles. The reduction in the concentration of pollutant gases and dust particles did vary at each observation location; this was due to the sensitivity of the equipment, the character of each observation location, and the placement of measuring devices. Urban areas filled with community activities have experienced the greatest improvement in air quality compared to suburban areas. Order of measuring instruments close to the location of pollutant sources, even in suburban areas, will decrease the concentration of pollutant gases, similar to that in urban areas. The difference between PM25 data during Nyepi 2022 and the average PM25 for 2020 - 2022 shows a decrease in PM25 concentrations of around 47%, with the highest drop at night.

Evaluation of radon gas air concentration in schools in Waist, Iraq

In this research, radon concentrations were measured in schools in Wasit city in Iraq, where radon gas concentration levels were measured for 40 schools in Wasit city, and the results indicated that radon concentration levels ranged between 3.000-50.00 Bq/m3 with an average value of 18.05±1.728 Bq/m3, and the results of some radiation coefficients related to radon concentration as the average annual effective dose (AED) given to students and staff from each school was much lower than the ICRP limit for 1993 of (3-10) mSv/year and is now about 0.3935 ± 0.046 mSv/year All AED values are lower than the ICRP limit for 1993 of (3-10) mSv/year The results of the pulse effective dose with an average value of 1.165 ± 0.12 spep/year The results of the paec with an average value of 1.4863, which shows that the paec results are much lower than the level unscear. Current NCRP values, 1989. The results of lung cancer cases per year per million persons (CPPP) had a mean value of 9.196 ± 0.877. The population-weighted mean values were below the ICRP 1993 limit of (170-230) per year per million persons, and it can be concluded that the radon concentrations measured in Wasit Governorate schools are within the acceptable limits and there is no radiation hazard.

Survey on Tree Carbon Stock inside Mahendra Multiple Campus, Nepalgunj, Banke

Carbon stock in plant bodies is the significantly longer period reservoir for the atmospheric CO2 that causes adverse impacts on living and non-living climatic and environmental factors while increasing its proportional concentration in air. The present study aimed to estimate the carbon stock in trees of Mahendra Multiple Campus territory. The study was carried out by purposive sampling method, where altogether ten plots were laid of size 8.92m radii and measured diameter at breast height (DBH) (1.3m) and angle of inclination was taken from 5m horizontal distance from the tree pole. The calculation was made following the equation given by Chave et al., 2005 for wet forests. In total 17 species of trees were reported with the dominant species Dalbergia sissoo followed by Corymbia citriodora based on DBH and population density. The total carbon stored by trees inside the territory of MMC, Nepalgunj was 76.44 tons per hectare which is approximately 1/3rd of the world’s tropical forest average carbon stock. It implies the importance of trees outside the forest in carbon sequestration and balancing carbon emissions. Further estimation of carbon dioxide emitted from the territory, by different carbon emitters inside the area is recommended.

A SCREENING OF THE HYDROGEN SULFIDE LEVELS IN PLOIEȘTI CITY, ROMANIA

Oil refineries and petrochemical facilities contribute to the pollution of the environment either air, water, or soil releasing hazardous and toxic air pollutants into the atmosphere. These include nitrogen oxides (NOx), carbon monoxide (CO), hydrogen sulfide (H2S), sulfur dioxide (SO2), and particulate matter (PM), affecting both environment and human health. In the range of air pollutants, hydrogen sulfide is less monitored and reported despite its importance in determining adverse effects. Background H2S concentrations in air were found to range commonly from 0.11 ppb to 0.33 ppb. The concentrations in urban areas can reach 1 ppb (~1.4 g m-3) up to more than 90 ppb (~125 g m-3) near sources of H2S emissions. In Romania, the standard for the air in protected areas for the hydrogen sulfide pollutant provides an admissible concentration, over a maximum interval of 30 minutes, of 15 µg/m³. Everything that exceeds this value is considered harmful to human health. The statistics for the H2S time series recorded in Ploiești City by the mobile laboratory of the Environmental Protection Agency Prahova between 2019 and 2021 with a sampling rate of 30 minutes showed that the mean ranged between 1.51 and 3.74 µg/m³, while the maximum reached 59.36 µg/m³ in the east of Ploiești in 2019. Overall, the highest variance occurred in the East and North parts due to the presence of the concentration peaks. Hydrogen sulfide must be considered on the public health agenda, both from the occupational perspective and for the ambient concentrations near significant H2S sources and in background urban areas. The monitoring infrastructure needs to be improved to allow continuous surveillance to ensure reliable databases that support research regarding the health effects of H2S across the concentrations occurring in the urban environment.

Occupational inhalation exposure during surface disinfection—exposure assessment based on exposure models compared with measurement data

BackgroundFor healthcare workers, surface disinfections are daily routine tasks. An assessment of the inhalation exposure to hazardous substances, in this case the disinfectant´s active ingredients, is necessary to ensure workers safety. However, deciding which exposure model is best for exposure assessment remains difficult.ObjectiveThe aim of the study was to evaluate the applicability of different exposure models for disinfection of small surfaces in healthcare settings.MethodsMeasurements of the air concentration of active ingredients in disinfectants (ethanol, formaldehyde, glutaraldehyde, hydrogen peroxide, peroxyacetic acid) together with other exposure parameters were recorded in a test chamber. The measurements were performed using personal and stationary air sampling. In addition, exposure modelling was performed using three deterministic models (unsteady 1-zone, ConsExpo and 2-component) and one modifying-factor model (Stoffenmanager®). Their estimates were compared with the measured values using various methods to assess model quality (like accuracy and level of conservatism).ResultsThe deterministic models showed overestimation predominantly in the range of two- to fivefold relative to the measured data and high conservatism for all active ingredients of disinfectants with the exception of ethanol. With Stoffenmanager® an exposure distribution was estimated for ethanol, which was in good accordance with the measured data.Impact statementTo date, workplace exposure assessments often involve expensive and time consuming air measurements. Reliable exposure models can be used to assess occupational inhalation exposure to hazardous substances, in this case surface disinfectants. This study describes the applicability of three deterministic and one modifying-factor model for disinfection of small surfaces in healthcare settings, in direct comparison to measurements performed and will facilitate future exposure assessments at these workplaces.

Acute bronchitis - modern possibilities of mucactive therapy

Analysis of the clinical effectiveness and safety of erdosteine use in comparison with standard (real practice) mucoactive therapy in patients with acute bronchitis (АВ) in adults. The observational program included 100 adult patients with АВ, 50 of them (group 1) received erdosteine, the group 2 also included 50 patients who received acetylcysteine, bromhexine and other mucolytics (real clinical practice). The following were assessed: cough severity, average time for resolution of night and daytime cough, satisfaction with treatment, NO concentration in exhaled air, levels of C-reactive protein (CRP) and interleukin-6 (IL-6). The average duration of relief of severe daytime cough requiring continued therapy was: in group 1 - 3.7±0.46 days, night cough - 1.14±0.94 days. In the second group, daytime cough was relieved in 3.8±0.4 days, night cough - 1.08±0.7 days. The duration of mucoactive therapy in group 1 was 5.32±0.82 days, in group 2 this figure was 8.5±1.4 days (p<0.05). The number of АВ patients with a significant reduction in the severity of productive cough (1 point on cough severity scale) on the 6th day from the beginning of treatment in group 1 (erdosteine) amounted to 32 (64%), in group 2 - 27 (54%). Satisfaction with the treatment was higher in the group receiving erdosteine: according to the indicators "very satisfied" and "extremely satisfied" the patients of the group 1 - 42 - were the leaders in comparison with the group 2, where these positions were marked by 28 patients. The level of CRP in patients with АВ in group 1 was 24.7±21.24 mg/l, in group 2 - 16.37±16.5 mg/l, which indicates the viral etiology of the process and no need in the prescription of antimicrobial drugs. For the first time in Russian practice, the following were determined: the level of IL-6, which in the group 1 was 10.3±6.7 pc/ml; in the group 2 - 10.03±3.94 pc/ml; the level of exhaled NO in group 1 was 16.5±5.1 ppb, in group 2 - 14.9±4.6 ppb (the norm is up to 25 ppb). These indicators, against the background of mucoactive therapy, decreased to normal values by 6th day. The findings expand our understanding of АВ in adults. New results have been obtained on the role of CRP, IL-6 and NO in exhaled air during АВ. The use of erdosteine was accompanied by a significant mucoactive effect in the form of a pronounced regression of cough in patients with АВ compared to the comparison group in shorter term.

Study of variation of indoor radon levels in houses and prediction of indoor concentrations using house characteristics and outdoor radon levels.

The measurement of 222Rn concentrations in indoor and outdoor air was carried out in certain locations of Mandya city, Karnataka, using the Solid State Nuclear Track Detectors (SSNTD) technique. The annual mean values of 222Rn in indoor and outdoor are found to be 20.5±1.4 and 9.0±0.5Bqm-3, respectively. The observed mean value of indoor radon concentration is found to be well within the world and the Indian average of 40 and 42Bqm-3, respectively. Outdoor radon concentrations have been measured in the vicinity of houses where yearlong radon measurements carried out using the SSNTD technique. The seasonal variation in the outdoor radon was studied and the average concentrations during summer, rainy and winter are 9.1, 6.9 and 12.9Bqm-3 respectively. Considering the possible factors such as house characteristics (Volume, Surface area of building material, Leakage area, etc.), indoor-outdoor temperature difference and outdoor radon concentration into account, the indoor radon levels were predicted using the existing model which is based on the mass balance equation. The results are systematically analysed and discussed. The predicted values are compared with the measured values.

Determination of odour emission rates emitted by active area sources and dispersion of odour concentration in the surrounding air

In this study, the area of a biofilter representing an active area source was sampled by taking 12 odour samples from the gaseous effluent and measuring the physical parameters of the source, so that we can obtain the odour emission rate (OER) specific to the source. The odour sampling process is a crucial step in the assessment and monitoring of odour pollution. Direct measurement of odour concentration in the ambient air is often not sufficient to determine whether an activity is responsible for producing olfactory discomfort to the receptors. To observe the contribution of the source to olfactory pollution and air quality by estimating the odour concentration in the ambient air, the odour emission rate (OER) was taken into account, which is expressed in odour units per second (ouE/s) and is obtained as the product of the odour concentration and the airflow rate associated with the source. The odour emission rate was entered into the dispersion program AERMOD for mathematical modeling. In order to estimate the odour concentration in the surrounding air in the adjacent areas to the sampled biofilter, 2 mathematical models were made to illustrate the odour concentration on the site and in its vicinity in the most unfavorable weather conditions „Highest values” and „98th Percentile” to illustrate the concentration in the surrounding air excluding the 2% unfavorable weather condition.

Past and recent changes in the pollution characteristics of PM10 and SO2 in the largest industrial city in South Korea

PM10 and SO2 are major air pollutants in Ulsan, the largest industrial city in South Korea. The purpose of this study was to evaluate the effectiveness of pollution reduction policies by comparing the pollution characteristics of PM10 and SO2 between 2012 and 2020. The concentrations of PM10 and SO2 have substantially decreased over time. Local industry was the primary driver of SO2 levels, whereas various sources were associated with PM10 levels. In 2012 and 2020, the spatial distributions of SO2 were similar, with hot spots around petrochemical and nonferrous industrial complexes, whereas the sources of PM10 differed between the two years. Although industrial emissions of PM10 decreased from 2012 to 2020, the concentrations derived from an air dispersion model were slightly higher in 2020 due to changes in both wind patterns and the strength of the emission sources. In contrast, modeled SO2 levels were higher in 2012 than in 2020 due to greater emissions in 2012. Eastern and northeastern China were identified as potential source areas for the long-range atmospheric transport of both PM10 and SO2, though its influence was significantly lower in 2020. A comparison of the PM10 and SO2 concentrations predicted by a random forest model and the measured concentrations indicates that government policies have been effective in reducing the emissions and ambient air concentrations of both pollutants. In conclusion, this study demonstrates that local industry remains a significant contributor to air pollution in Ulsan despite the effects of governmental policy. Furthermore, as the influence of external sources weakens, there is a pressing need to strengthen the management of local sources to effectively mitigate air pollution in Ulsan.

Air monitoring of organochlorine pesticides (OCPs) in Bursa Türkiye: Levels, temporal trends and risk assessment

Monitoring concentration levels of persistent organic pollutants (POPs) is required to evaluate the effectiveness of international regulations to minimize the emissions of persistent organic pollutants (POPs) into the environment. In this manner, we evaluated the spatial and temporal variations of 22 organochlorine pesticides (OCPs) using polyurethane foam passive air samplers at ten stations in Bursa in 2017 and 2018. The highest concentration value for Σ22OCPs was detected in Ağaköy (775 pg/m3) and Demirtaş (678 pg/m3) sampling sites, while the lowest value was observed in Uludağ University Campus (UUC, 284 pg/m3) site. HCB, γ-HCH, Endo I, and Mirex were the most frequently detected OCPs, which shows their persistence. Diagnostic ratios of β−/(α + γ)-HCH have pointed to historical and possible illegal OCP usage in the study area. The seasonality of air concentrations (with spring and summer concentrations higher than winter and autumn concentrations) was well exhibited by α-HCH, β-HCH, ɣ-HCH, HCB, Endo I, and Mirex but not aldrin, dieldrin, and α-chlordane (CC). Levels of OCPs detected in ambient air in the current study were relatively similar to or lower than those reported in previous studies conducted in Türkiye. Back trajectory analysis was applied to identify the possible sources of OCPs detected in the sampling regions. The Clausius-Clapeyron approach was used to investigate the temperature dependence of OCP gas-phase atmospheric concentrations. The data showed that long-range atmospheric transport affects ambient air OCP concentrations in the study area.

Carbon dioxide uptake and fixation by ferrous iron-oxidizing acidophilic bacteria

CO2 is a major nutrient for autotrophic, mineral sulfide-oxidizing bacteria. The uptake and fixation of this carbon source is therefore critical for industrial mineral sulfide bioprocessing. The CO2 concentration influenced growth of five iron- or sulfur-oxidizing acidophiles to different extents. Those less affected by a growth-limiting CO2 concentration included Acidithiobacillus ferrooxidans and Acidithiomicrobium ferrooxidans. Acidithiobacillus ferrooxidans showed efficient uptake of 14CO2 from its concentration in air when previously grown under air while the maximum rate of CO2 uptake by cells previously grown under an enhanced CO2 concentration was only approached when the CO2 was increased to 0.1% v/v in air. In contrast, growth of Sulfobacillus thermosulfidooxidans was more adversely affected by limiting CO2 under air and the CO2 uptake rate was the same in cells grown with limiting or excess CO2. At. ferrooxidans also appeared to fix accumulated CO2 more efficiently than S. thermosulfidooxidans and RT-qPCR confirmed that adaptation of At. ferrooxidans to growth under limiting CO2 included production of form 1A ribulose bis-phosphate carboxylase in place of the form 1Aq enzyme which was predominant during growth under an enhanced CO2 concentration.

Near-field exposures and human health impacts for organic chemicals in interior paints: A high-throughput screening

Interior paints contain organic chemicals that might be harmful to painters and building residents. This study aims to develop a high-throughput approach to screen near-field human exposures and health impacts related to organic chemicals in interior paints. We developed mass balance models for both water- and solvent-based paints, predicting emissions during wet and dry phases. We then screened exposures and risks, focusing on Sri Lanka where residential houses are frequently repainted. These models accurately predict paint drying time and indoor air concentrations of organic chemicals. Exposures of both painter and household resident were estimated for 65 organic chemicals in water-based and 26 in solvent-based paints, considering 12 solvents. Chemicals of concerns (CoCs) were identified, and maximum acceptable chemical contents (MACs) were calculated. Water-based paints generally pose lower health risks than solvent-based paints but might contain biocides of high concern. The total human health impact of one painting event on all household adults ranges from 1.5 × 10-3 to 2.1 × 10-2 DALYs for solvent-based paints, and from 4.1 × 10-4 to 9.5 × 10-3 DALYs for water-based paints. The present approach is a promising way to support the formulation of safer paint, and is integrated in the USEtox scientific consensus model for use in life cycle assessment, chemical substitution and risk screening.