Inorganic Air Research Articles

Interpretation of odor complaint records with BTEX pollutants and meteorological factors: Çorlu case study

Air pollution in urban areas increases as a result of emitted air from different sources within the mixing layer of troposphere. Odor pollution is amongst the primary reasons behind environmental nuisance and occurrence of citizen complaints. Frequent exposure to odorous compounds and/or odor nuisance are increasingly associated with air pollution problems. Besides, there is no universally accepted environmental odor management method reported so far. Level of air pollutants emission, distance of emission sources to residential areas, to-pography, geographical and meteorological conditions have influence on imposed level of air pollution and odor pollution in cities.
 
 This study is built on the citizen odor complaint data (based on frequency, intensity, duration, odor tone and location (namely the FIDOL factors) collected in Çorlu/Tekirdağ through the GIS integrated public participated platform, namely the Çorlu KODER mobile application. The annual odor complaint data was briefly introduced and given an evaluation with the mo-bile app users demographic information. The obtained data between August 28-November 2 of 2021, was subjected to interpretative evaluation and statistical analysis with BTEX (benzene, toluene, ethylene benzene and xylen) concentrations, inorganic air pollution concentrations and meteorological factors. In light of the obtained results, temperature, wind speed, relative humidity and toluene concentration were found to play a significant role on the number of citizen odor complaints. The EU reported limit value, lower rating threshold and upper rating threshold for BTEX pollutants have been exceeded several times.
 
 The average Toluene/benzene ratios obtained during the study show that; non-traffic sources contribute significantly to VOC emissions. Air pollutants transportation mechanism from neighbouring OIZ settlements become a prominent justification and support the hypothesis that residential areas of Corlu are under the effect of industrial air pollution and odor pollution con-stituents. There is low level of negative correlation between the benzene measured in Çorlu and WS (r=-0.63). Below 2.4 m/s, the average number of odor complaints (ANOC) tend to increase, while above this level odor complaints are diminished). The ANOC remained around 4 for[C] < 4 ug/m3 and reached to 18 for [C]BTEXtotal > 8 ug/m3. Above [C]Toluen=3 ug/m3 conditions, Daily ANOC increase from 7 to 19. Over [C]Toluen= 4 ug/m3 conditions, it reached up to 23. Increses in the number of daily ANOC by temperature is distinct over 21 C0 and reaches to 35. 
 
 The GIS integrated citizen complaint collection platforms are critical for real-time data collection of environmental complaints with high spatiotemporal accuracy. Citizen odor complaint surveys are useful monitoring tools and obtained data sets can be used to identify sensitive areas where and when specific actions should be taken and air pollutants measuement studies be performed.

Potential effect of atmospheric condition on incident light and photo-production of reactive intermediates in freshwater systems

The effect of local atmospheric conditions on aquatic photochemical reactions has been rarely explored because of the difficulty in field observation. Thus, this study aimed to elucidate the effects of atmospheric conditions, which are inorganic air pollution, aerosol pollution, and ozone layer depletion, on the incident light and photo-production of reactive intermediates (RIs). Models of SMARTS (Simple Model for the Atmospheric Radiative Transfer of Sunshine) and APEX (Aqueous Photochemistry of Environmentally occurring Xenobiotics) were used to simulate the changes in wavelength profile and steady-state concentrations of RIs, which are hydroxyl radical, carbonate radical, singlet oxygen, and triplet-state of dissolved organic matter. Results showed that inorganic air pollution and aerosol pollution have a reduction effect on the production of RIs, while ozone layer depletion increases the production of RIs. Among them, inorganic air pollution has the largest influence on the production of RIs which were expected to reduce by 80%–90% in extreme pollution. This study also investigated the potential effect of water constituents (i.e., NO3−, dissolved organic matter, and HCO3−) on the relation between atmospheric conditions and the production of RIs. NO3− concentration under different atmospheric conditions showed the most influence on the production of RIs. This study highlighted the importance of considering atmospheric conditions when assessing the photochemical persistence of organic pollutants. Even though these results are model output, they quantitatively revealed the potential influence of atmospheric conditions on the production of RIs in freshwater systems.

Co-occurrence of airborne biological and anthropogenic pollutants in the central European urban ecosystem.

The interactions between organic and inorganic air pollutants, enhanced by the impact of weather parameters, may worsen the respiratory allergy symptoms in allergy sufferers. Pollen grains and fungal spores belong to some of the most crucial aeroallergens. Other allergenic bioparticles in the atmospheric microbiome can include microalgae, fern spores and mites. In this study, we evaluated if and to what extent air pollutants and weather parameters drive the daily variation in airborne concentrations of broad spectrum of bioparticles (pollen grains, fungal spores, microalgae, fern spores and invertebrates) in the air of Bratislava over 3years, 2019-2021. Air samples were collected using a Hirst-type volumetric sampler. Based on the results of Spearman's correlation analysis, air temperature seems to be the most influential meteorological factor, positively associated with the concentration of all types of bioparticles at assemblage level, even though the association with microalgae was negative. Wind speed, known to have a diluting effect on most airborne particles, appears to be the most influential for microalgae, as their concentration in the air increases along with rising wind speed. Considering air pollutants, correlation analysis revealed that as the daily concentrations of ozone, PM10, CO and/or NO2 increased, so did the levels of most types of analysed bioaerosols at the assemblage level. Regarding that bioparticles may act as carriers for inorganic particles and amplify their allergenic impact, a concomitant increment in the airborne concentration of both organic and inorganic pollutants poses a threat to allergy sufferers in the study area. The concentration of microalgae, on the other hand, decreases with rising levels of CO, NO2 and PM10; thereby, their synergistic effect on allergy sufferers is negligible. Based on our findings, we suggest that the response of pollen and fungal spore concentration to environmental conditions should be investigated at the taxon, not the assemblage level, as each pollen/spore taxon has a different pattern in response to meteorological parameters and air pollutants.

Neutron Activation Analysis of PM10 for Air Quality of an Industrial Region in the Czech Republic: A Case Study

This work was conducted to focus on pollutant transmission between Poland and Czechia at the most polluted area in the Czech Republic, the Moravian Silesian region. Instrumental neutron activation analysis (INAA) and multivariate statistical analyses were used to determine the mass fractions of inorganic air pollutants accumulated on filters. Particle matters of sizes smaller than 10 µm (PM10) were collected using a high-volume sampler (SAM Hi 30 AUTO WIND). Pollutants PM10 were collected on Whatman QM-A Quartz Microfiber Filters of 150 mm in diameter based on various wind conditions. These filters were irradiated by neutron flux at the experimental reactor IBR-2 at the Joint Institute of Nuclear Research in Dubna, RF. Irradiated samples were measured by gamma spectrometry techniques using HPGe detectors. In total, results are shown for 49 samples (from March to July 2021) and five field blank filters. The mass fractions of 24 elements (Sc, Cr, Fe, Ni, Co, Zn, Se, As, Br, Rb, Mo, Sb, Ba, Cs, La, Ce, Sm, Eu, Tb, Yb, Hf, Au, Th, and U) were determined. The sources of pollution were specified using correlation and exploratory factor analyses and including meteorological conditions. A strong positive correlation was shown between the elements Cr, As, Br, Co, Fe, Sc, Se, Sm, Th, La, and Ce. Elemental exposure to PM10 can be divided based on the factor loadings of common chemical components into three main pollution sources. According to the wind rose, the pollution came from the southeast/west direction; therefore, we can assume that the pollution most likely originated from the metallurgic complex (steel and iron production in the southeast, and a coking plant, metal foundry, and generation plant in the west).

Gas sensing of fibrous red phosphorene towards inorganic air pollutants: Insights from first-principles calculations

Environmental protection and public security make atmospheric monitoring as an important challenge. Two dimensional materials with unique physical and chemical properties are ideal candidates as gas-sensing materials. Here, we report the adsorption characteristics of fibrous red phosphorene based on first-principles calculations. The calculated adsorption energies, Bader’s charge transfer, electronic structures reveal that the adsorption of NO, NO2, O3 and SO2 leads to significant changes in electronic structures, which is suitable for gas sensing. The decrease in work function reveals that fibrous red phosphorene is also a field-effect transistor candidate for the specific detection of NO. Among considered gas molecules, only the sensing performance of NO can be enhanced by applying external in-plane strain. The calculation results could provide an atomistic insight and a better understanding of sensing properties of fibrous red phosphorene.

Rehabilitation of Asphalt Pavement to Improvement the Mechanical and Environmental Properties of Asphalt Concrete by Using of Nano Particles

Dealing with the pollution released into the air by vehicles is a major concern for many countries around the world. There is an increasing trend toward environmental considerations as well as road logistics issues, resulting in doing experiments on new materials, which can help reducing the amount of pollutants in the atmosphere. In this research, the photo catalytic properties of Nano TiO2/SiO2 used over the asphalt roads in order to absorb the pollution substances from the atmosphere are investigated. The above mentioned compound reacts with UV light and oxidizes the pollutant particles including nitrogen oxides (NOx) as well as volatile organic compounds (VOC). In this method, the sol-gel technique was used to produce photo catalyst based on TiO2/SiO2. One purpose of this research is to examine the photo catalytic properties of the compound when it is used in a hot mix asphalt (HMA). Another aim of the study is to find and describe both rheological and mechanical characteristics of the hot mix asphalt (HMA) as well as the Nano modified agents. The resulting asphalt would have the advantages of HMA, including lower energy requirements and less emission during production, while having photo catalytic characteristics of TiO2/SiO2 to absorb and decompose the organic and inorganic air pollutants. The outcomes of the tests showed that adding the Nano TiO2/SiO2 modifier to the asphalt binder effectively removed NOx particles from the air and enhanced the rheological properties of bitumen. It also enhanced the hardness and viscosity of the pavement, while reducing its penetration and fatigue life. When TiO2/SiO2 was sprayed as a water based coating, the efficiency of NOx reduction ranged between 41 and 63%.

Titanium dioxide as a photocatalyst to create self-cleaning concrete

The use of Titanium Dioxide (TiO2) in the form of Ultrafine particles as a coating for concrete pavement have received considerable attention in recent years as these particles can trap anti compose organic and inorganic air pollutant by photocatalytic process. In spite of these promising benefits, durability and resistance to wear a of Titanium Dioxide (TiO2) coatings has not been evaluated. The objective of this study is to determine photocatalytic effect on concrete with spectrophotometer and its effect on environment. We prepared samples of varying % of TiO2 and checked the effect on its strength, and its ability to resist the radiations and compared their results with normal concrete.

Phytoremediation Mechanisms in Air Pollution Control: a Review

Air pollutants originated from natural and anthropogenic sources and able to bio-magnify and bio-accumulate in the trophic levels, thus increase toxicity in the food chain. Various air pollutants (particulate matters (PMs), volatile organic compounds (VOCs), inorganic air pollutants (IAP), persistent organic pollutants (POPs), heavy metals, and black carbon) resulted in adverse effects on environmental and human health after prolonged exposure. These airborne particles can travel in gaseous form for long distance and deteriorate the air quality of downstream areas. Air pollution abatement can be implemented by reducing emissions at source and purifying pollutants with remediation techniques. However, air pollution remained as the dominant issue to cause burden in human and ecosystem well-being. Due to drawbacks like expensive, high maintenance, and likelihood for pollutants’ reemission, existing conventional remediation technologies is insufficient for air pollutants mitigation. Phytoremediation enters the picture of air pollution control as a cost-effective, energy-saving, and environmental-friendly technology in remediating air pollutants. In phytoremediation, plant organs and associating microbes in the phyllosphere and rhizosphere interacted with each other to remediate air pollutants. Phytoremediation of air pollutants involves the rhizosphere of plants as pollutants may deposit in the soil during leaf fall and precipitation. Additionally, the phytoremediation mechanisms involve phytoextraction, phytovolatilization, phytodegradation, phytostabilization, rhizodegradation, and rhizofiltration. A brief overview of phytoremediation mechanisms for each air pollutants is presented. In short, the benefits of phytoremediation and its associated gaps in air pollution control are described.

Selective removal of organic and inorganic air pollutants by adjusting the g-C3N4/TiO2 ratio

During the recent years, g-C3N4/TiO2 composites have been regarded as efficient photocatalysts for the removal of air pollutants. The combination of these materials gives excellent photocatalytic performances, as each ones advantage covers the disadvantages of the other. In the present study, g-C3N4/TiO2 heterostructures were synthesized by mixing chemically exfoliated g-C3N4 with commercial TiO2 P25 in different ratios and were examined for the removal of NOx and acetaldehyde under visible-light irradiation. The results of photocatalytic tests in correlation with the EPR experiments revealed that heterostructures containing higher amount of TiO2 are efficient in systems where the attack of hydroxyl radicals prevails (acetaldehyde), while dominant g-C3N4 content provides effectiveness in systems where superoxide radical anions play the key role (NOx). This outcome is directly coupled with the energy positions of conduction- and valence-band edges of each material.

Effects of Water Removal Devices on Ambient Inorganic Air Pollutant Measurements.

Water vapor is a pivotal obstacle when measuring ambient air pollutants. The effects of water vapor removal devices which are called KPASS (Key-compound PASSer) and Cooler. On the measurement of O3, SO2, and CO at ambient levels were investigated. Concentrations of O3, SO2, and CO were 100 ppb, 150 ppb, and 25 ppm, respectively. The amount of water vapor varied at different relative humidity levels of 30%, 50%, and 80% when the temperature was 25 °C and the pressure was 1 atm. Water vapor removal efficiencies and recovery rates of target gases were also determined. The KPASS showed a better performance than the Cooler device, removing 93.6% of water vapor and the Cooler removing 59.2%. In terms of recovery, the KPASS showed a better recovery of target gases than the Cooler. Consequently, it is suggested that the KPASS should be an alternative way to remove water vapor when measuring O3, SO2, and CO.

Exposure to organic and inorganic traffic-related air pollutants alters haematological and biochemical indices in albino mice Mus musculus

ABSTRACTThe relationship between air pollution exposure and haematology remains controversial. Evidences in the effect of trace organic air pollutants and in the impact of such exposure on lipid and protein levels are scarce. This work investigated the health effects of medium-term exposure to traffic-related air pollution on both haematological and biochemical indices in animal models. Two groups of albino mice (Mus musculus) were exposed to ambient air polluted by vehicle exhaust for three and six months, and one group was kept as control. Results found significant depletions (p < 0.05) in red blood cells, packed cell volume, neutrophils, eosinophils, monocytes, and total cholesterol after air pollution exposure. On the contrary, significant elevations (p < 0.05) were observed in platelet, lymphocytes, and serum albumin compared to control condition. Correlation data suggested that significant changes in blood parameters may be altered by the synergistic effect of several organic and inorganic air pollutants.

Spatial Distribution of BTEX and Inorganic Pollutants During Summer Season in Yalova, Turkey

Abstract The objective of this research is to determine the atmospheric concentrations and spatial distribution of benzene (B), toluene (T), ethylbenzene (E) and xylenes (X) (BTEX) and inorganic air pollutants (O3, NO2 and SO2) in the Yalova atmosphere during summer 2015. In this study, a combination of passive sampling and Geographical Information System-based geo-statistics are used with spatial statistics of autocorrelation to characterise the spatial pattern of the quality of air based on concentrations of these pollutants in Yalova. The spatial temporal variations of pollutants in the air with five types of land-use, residence, rural, highway, side road and industrial areas were investigated at 40 stations in Yalova between 7th August 2015 and 26th August 2015 using passive sampling. An inverse distance weighting interpolation technique was used to estimate variables at an unmeasured location from observed values at nearby locations. The spatial autocorrelation of air pollutants in the city was investigated using the statistical methods of Moran’s I in addition to the Getis Ord Gi. During the summer, highway and industrial sites had higher levels of BTEX then rural areas. The average concentration of toluene was measured to be 5.83 μg/m3 and this is the highest pollutant concentration. Average concentrations of NO2, O3 and SO2 are 35.64, 84.23 and 3.95 μg/m3, respectively. According to the global results of Moran’s I; NO2 and BTEX had positive correlations on a global space at a significant rate. Moreover, the autocorrelation analysis on the local space demonstrated significant hot spots on industrial sites and along the main roads.

PM2.5 Exposure Suppresses Dendritic Maturation in Subgranular Zone in Aged Rats

Detrimental effects of long-term inhalation of fine particulate matter (PM2.5) on the pulmonary and cardiovascular systems have been widely reported. Recent studies have shown that exposure to PM2.5 also causes adverse neurocognitive effects. This study investigates the effects of inhaled ammonium sulfate, which is a major compound of inorganic air pollutants in PM2.5, on adult neurogenesis in aged Sprague-Dawley rats. A total of 20 rats were randomly assigned to experimental (n = 10) and control (n = 10) conditions, wherein they were exposed to either ammonium sulfate or sham air for 2 h per day and for 28 consecutive days. It was observed that ammonium sulfate inhibited the maturation process and diminished dendritic complexity of immature neurons in the subgranular zone (SGZ) of the hippocampus significantly, although the number of neural stem cells or the rates of differentiation were comparable between the two groups. Our findings provide clear evidence on the direct relationship between air quality and advantageous neurogenesis. Exposure to PM leads to specific adverse effects on the maturation process during neurogenesis.

Public Health Costs of Primary PM2.5 and Inorganic PM2.5 Precursor Emissions in the United States.

Current methods of estimating the public health effects of emissions are computationally too expensive or do not fully address complex atmospheric processes, frequently limiting their applications to policy research. Using a reduced-form model derived from tagged chemical transport model (CTM) simulations, we present PM2.5 mortality costs per tonne of inorganic air pollutants with the 36 km × 36 km spatial resolution of source location in the United States, providing the most comprehensive set of such estimates comparable to CTM-based estimates. Our estimates vary by 2 orders of magnitude. Emission-weighted seasonal averages were estimated at $88,000-130,000/t PM2.5 (inert primary), $14,000-24,000/t SO2, $3,800-14,000/t NOx, and $23,000-66,000/t NH3. The aggregate social costs for year 2005 emissions were estimated at $1.0 trillion dollars. Compared to other studies, our estimates have similar magnitudes and spatial distributions for primary PM2.5 but substantially different spatial patterns for precursor species where secondary chemistry is important. For example, differences of more than a factor of 10 were found in many areas of Texas, New Mexico, and New England states for NOx and of California, Texas, and Maine for NH3. Our method allows for updates as emissions inventories and CTMs improve, enhancing the potential to link policy research to up-to-date atmospheric science.

Tailoring the energy band gap and edges’ potentials of g-C3N4/TiO2 composite photocatalysts for NOx removal

Graphitic carbon nitride/titania (g-C3N4/TiO2) composite photocatalysts with different C3N4/TiO2 ratios were synthesised by a simple preparation route through annealing the mixtures of melamine and commercial TiO2 P25 powder at 550°C for 3h under Ar flow. The resulting composite photocatalysts were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and electrochemical impedance spectroscopy. The photocatalytic activity of the composites was evaluated using NO as a target inorganic air pollutant. Variation of the initial weight ratio of melamine precursor/TiO2 (3:1, 1:1, 2:3, 1:3, 1:4 and 1:7) allowed tuning of the composites’ band gap from 2.66eV in pure g-C3N4 to 3.14eV in pure P25 as revealed by UV–visible spectroscopy. The conduction band edges position determined by electrochemical measurements using Mott–Schottky relation varied from ∼−1.27eV in pure g-C3N4 to ∼−0.67eV in pure P25 (vs NHE, pH 7). Under visible light, the g-C3N4/TiO2 composite with initial ratio 1:4 exhibited superior photocatalytic activity in NO oxidation in comparison to the pure semiconductors g-C3N4 and TiO2. This finding was explained to be a result of a combination of the optical and electronic properties of the composites.

The Role of Plant-Microbe Interactions and Their Exploitation for Phytoremediation of Air Pollutants.

Since air pollution has been linked to a plethora of human health problems, strategies to improve air quality are indispensable. Despite the complexity in composition of air pollution, phytoremediation was shown to be effective in cleaning air. Plants are known to scavenge significant amounts of air pollutants on their aboveground plant parts. Leaf fall and runoff lead to transfer of (part of) the adsorbed pollutants to the soil and rhizosphere below. After uptake in the roots and leaves, plants can metabolize, sequestrate and/or excrete air pollutants. In addition, plant-associated microorganisms play an important role by degrading, detoxifying or sequestrating the pollutants and by promoting plant growth. In this review, an overview of the available knowledge about the role and potential of plant–microbe interactions to improve indoor and outdoor air quality is provided. Most importantly, common air pollutants (particulate matter, volatile organic compounds and inorganic air pollutants) and their toxicity are described. For each of these pollutant types, a concise overview of the specific contributions of the plant and its microbiome is presented. To conclude, the state of the art and its related future challenges are presented.

Supervised Intelligence Committee Machine to Evaluate Field Performance of Photocatalytic Asphalt Pavement for Ambient Air Purification

The ability of a titanium dioxide (TiO2) photocatalytic nanoparticle to trap and to decompose organic and inorganic air pollutants makes it a promising technology as a pavement coating to mitigate the harmful effects of vehicle emissions. Statistical models and artificial intelligence (AI) models are two applicable methods to quantify photocatalytic efficiency. The objective of this study was to develop a model based on field-collected data to predict the nitrogen oxide (NOx) reduction. To achieve this objective, the supervised intelligent committee machine (SICM) method as a combinational black box model was used to predict NOx concentration at the pavement level before and after TiO2 application on the pavement surface. SICM predicts NOx concentration by a nonlinear combination of individual AI models through an artificial intelligent system. Three AI models—Mamdani fuzzy logic, artificial neural network, and neuro-fuzzy—were used to predict NOx concentration in the air as a function of traffic count and climatic conditions, including humidity, temperature, solar radiation, and wind speed before and after the application of TiO2. In addition, an intelligent committee machine model was developed by combining individual AI model output linearly through a set of weights. Results indicated that the SICM model could provide a better prediction of NOx concentration as an air pollutant in the complex and multidimensional air quality data analysis with less residual mean square error than that given by multivariate regression models.

Assessing the fate of nutrients and carbon in the bioenergy chain through the modeling of biomass growth and conversion.

A forest growth model was coupled to a model of combined heat and power (CHP) production in a gasification plant developed in Aspen Plus. For a given production, this integrated forest-to-energy model made it possible to predict the annual flows in wood biomass, carbon, and nutrients, including N, S, P, and K, from the forest to the air emissions (NOx, SOx, PAH, etc.) and ash flows. We simulated the bioenergy potential of pure even-aged high-forest stands of European beech, an abundant forest type in Northeastern France. Two forest management practices were studied, a standard-rotation and a shorter-rotation scenario, along with two wood utilizations: with or without fine woody debris (FWD) harvesting. FWD harvesting tended to reduce the forested area required to supply the CHP by 15–22% since larger amounts of energy wood were available for the CHP process, especially in the short-rotation scenario. Because less biomass was harvested, the short-rotation scenario with FWD decreased the nutrient exports per hectare and year by 4–21% compared to standard practices but increased the amount of N, S, and P in the CHP process by 2–9%. This increase in the input nutrient flows had direct consequences on the inorganic air emissions, thus leading to additional NOx and SO2 emissions. This model is a valuable tool for assessing the life cycle inventories of the entire bioenergy chain.

Indoor and Outdoor Biomonitoring Using Lichens at Urban and Rural Primary Schools

Monitoring particulate matter (PM) and its chemical constituents in classrooms is a subject of special concern within the scientific community in order to control and minimize child exposure. Regulatory sampling methods have presented several limitations in their application to larger number of classrooms due to operational and financial constraints. Consequently, passive sampling methodologies using filters were developed for indoor sampling. However, such methodologies could not provide parallel information for outdoors, which is important to identify pollution sources and assess outdoor contribution to the indoors. Therefore, biomonitoring with transplanted lichens, a technique usually applied for outdoor studies, was used both indoor and outdoor of classrooms. Three main objectives were proposed, to (i) characterize simultaneously indoor and outdoor of classrooms regarding inorganic air pollutants, (ii) investigate spatial patterns of lichen conductivity, and (iii) assess pollution sources that contribute to a poor indoor air quality in schools. Lichens Flavoparmelia caperata were transplanted to indoor and outdoor of classrooms for 59 d. After exposure, electric conductivity of lichens leachate was measured to evaluate lichen vitality and cell damage. Outdoors lichen conductivity was higher near the main highways, and indoors there was great variability in levels, which indicates different emissions sources and different ventilation patterns. Chemical content of lichens was assessed by instrumental neutron activation analysis (INAA), and As, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Na, Rb, Sb, Sc, Sm, Sr, Ta, Th, Yb, and Zn were determined. Element accumulation, crustal enrichment factors, and spatial variability of elements were analyzed and contaminants from anthropogenic sources, such as traffic (As, Sb, and Zn) and indoor chalk (Ca) found. Classrooms with potential indoor air quality problems were identified by presenting higher accumulations of inorganic pollutants in exposed biomonitors.

Sustainable Photocatalytic Asphalt Pavements for Mitigation of Nitrogen Oxide and Sulfur Dioxide Vehicle Emissions

The ability of titanium dioxide (TiO2) photocatalytic nanoparticles to trap and decompose organic and inorganic air pollutants render them a promising technology as a pavement coating to mitigate the harmful effects of vehicle emissions. This technology may revolutionize construction and production practices of hot-mix asphalt by introducing a new class of mixtures with superior environmental performance. The objective of this study was to assess the benefits of incorporating TiO2 into asphalt pavements. To achieve this objective, the photocatalytic effectiveness and durability of a water-based spray coating of TiO2 was evaluated in the laboratory. This study also presents the field performance of the country’s first air-purifying photocatalytic asphalt pavement, located on the campus of Louisiana State University. Laboratory evaluation showed that TiO2 was effective in removing NOₓ and SO2 pollutants from the air stream, with an efficiency ranging from 31–55% for NOₓ pollutants and 4–20% for SO2 pollutants. The maximum NOₓ and SO2 removal efficiencies were achieved at an application rate of 0.05 L/m². The efficiency of NOₓ reduction is affected by the flow rate of the pollutant, relative humidity, and ultraviolet (UV) light intensity. In the field, NOₓ concentrations were monitored for both the coated and uncoated sections to directly measure photocatalytic degradation. Furthermore, nitrates were collected from the coated and uncoated areas for evidence of photocatalytic NOₓ reduction. Results from both approaches show evidence of photocatalytic NOₓ reduction. Further field evaluation is needed to determine the durability of the surface coating.