Air Pollutants Nitrogen Dioxide Research Articles

Combination of toxicological and epidemiological approaches for estimating the health impact of atmospheric pollutants. A proof of concept for NO2

BackgroundRegular monitoring of the air pollutant nitrogen dioxide (NO2), an indicator for traffic-related emissions, is a priority in urban environments. The health impacts associated with NO2 exposure are the result of a combination of factors, including concentration, duration of exposure, and interactions with other pollutants. WHO has established air quality guidelines based on epidemiological studies. ObjectiveThis study develops a new concept "Health Impact Pathways (HIPs)" using adversity as a probabilistic indicator of health effects. For this purpose, it integrates available toxicological and epidemiological information, using Adverse Outcome Pathways (AOPs), in order to understand chemical-biological interactions and their consequences on health. MethodsLiterature review and meta-analysis of toxicological data supported by expert judgment were performed to establish: a) adversity pathways, b) quantitative criteria for scoring the observed toxicological effects (adversity indicators), c) NO2 exposure - adversity relationship for both long-term (1–36 months) and shortterm (1–7 days). The NO2 daily concentrations from January 2001 to December 2022, were obtained from Madrid city Air Quality network monitoring database. Adversity levels were compared with relative risk levels for all-cause and respiratory mortality estimated using linear equations from WHO 2021 guidelines. ResultsNon-linear relations were obtained for all long- and short-term NO2 related adversity indicators; for long-term effects, the best fitting was obtained with a modified Haber's law model with an exponential coefficient for the exposure time of 0.25. Estimations are presented for a set of case studies for Madrid city, covering temporal and spatial variability. A clear improvement trend along the two decades was observed, as well as high inter- and intra-station variability; the adversity indicators provided integrated information on the temporal and spatial evolution of population level risk. DiscussionThe proposed HIP conceptual approach offers promising advances for integrating experimental and epidemiological data. The next step is linking the concentration-adversity relationship with population health impacts through probability estimations, the preliminary estimations confirm the need for assessing independently different population groups.

The Environmental Pollutant NO3⋅ Rapidly Damages Alkene Moieties in Lipids Through Electron Transfer

AbstractThe presence of alkene moieties in fatty acids of (phospho)lipids and cholesterol derivatives makes them highly susceptible to damage by nitrate radicals (NO3⋅), potentially formed through simultaneous exposure to the environmental air pollutants nitrogen dioxide (NO2⋅) and ozone (O3). Absolute rate coefficients derived from reactions with simplified model systems range from 4 to 8×109 M−1 s−1 in acetonitrile, ranking among the highest determined for NO3⋅ reactions with biomolecules in solution to date. Alkenes featuring an electron‐withdrawing carbonyl substituent also display notable reactivity with k values of (2.5±1.0)×108 M−1 s−1. Calculations suggest that these reactions are initiated by oxidative electron transfer (ET) involving the C=C bond, followed by recombination of the resulting alkene radical cation with nitrate anion (NO3−) to form the nitrate adduct radical as the kinetically controlled product. Conversely, saturated fatty acid derivatives and cholestanol react with NO3⋅ through hydrogen atom transfer (HAT) with rate coefficients of 106–107 M−1 s−1, indicating that biomolecules with a considerable number of non‐ or moderately activated sp3 C−H bonds are also highly susceptible to NO3⋅ attack. These findings underscore the potential health hazards associated with exposure to combined NO2⋅ and O3 gases.

ASSESSING AIR POLLUTANT EMISSIONS IN THE AFTERMATH OF THE 2021 FOREST FIRES IN MARMARIS AND MANAVGAT, TÜRKİYE: INSIGHTS FROM SATELLITE-BASED MONITORING

Abstract. In recent years, the occurrence of forest fires has become almost inevitable worldwide due to the severe impact of climate change. Consequently, it is imperative to examine the consequences of these fires, pinpoint the affected areas, and take required measures following post-fire incidents. With the advent of modern remote sensing satellites, which allow for the rapid monitoring of vast expanses, they offer a valuable data source for addressing such emergency scenarios. Therefore, the main objective of this study is to evaluate the extent of air pollutant gas emissions resulting from the forest fires that occurred in Marmaris and Manavgat, Türkiye, in the summer of 2021. To this aim, using the data obtained from the TROPOspheric Monitoring Instrument (TROPOMI) sensor onboard the Sentinel-5P satellite, the amount of major air pollutants nitrogen dioxide (NO2), carbon monoxide (CO) and aerosol were investigated after the forest fires considering three different non-fire time periods. The findings of the experiments indicated that in Manavgat, there was a substantial rise in NO2 and average CO levels by 260.43% and 107.07%, respectively, when compared to the 10-day period preceding the forest fire event. Similarly, in Marmaris, there was an increase of 203.63% in NO2 levels and a 102.47% rise in average CO levels during the same period. Positive absorbing aerosol index (AAI) values were also observed during the events, which means that the amount of UV-absorbing aerosols increased due to the fire. The differenced Normalized Burn Ratio (dNBR) maps derived from the Sentinel-2 MSI imagery were also used to investigate the severity of the forest fires, and to observe the relationship between the fire severity level and the air pollutants investigated.

Leading determinants of incident dementia among individuals with and without the apolipoprotein E ε4 genotype: a retrospective cohort study

BackgroundLittle is known regarding the leading risk factors for dementia/Alzheimer’s disease (AD) in individuals with and without APOE4. The identification of key risk factors for dementia/Alzheimer’s disease (AD) in individuals with and without the APOE4 gene is of significant importance in global health.MethodsOur analysis included 110,354 APOE4 carriers and 220,708 age- and sex-matched controls aged 40–73 years at baseline (between 2006–2010) from UK Biobank. Incident dementia was ascertained using hospital inpatient, or death records until January 2021. Individuals of non-European ancestry were excluded. Furthermore, individuals without medical record linkage were excluded from the analysis. Moderation analysis was tested for 134 individual factors.ResultsDuring a median follow-up of 11.9 years, 4,764 cases of incident all-cause dementia and 2065 incident AD cases were documented. Hazard ratios (95% CIs) for all-cause dementia and AD associated with APOE4 were 2.70(2.55–2.85) and 3.72(3.40–4.07), respectively. In APOE4 carriers, the leading risk factors for all-cause dementia included low self-rated overall health, low household income, high multimorbidity risk score, long-term illness, high neutrophil percentage, and high nitrogen dioxide air pollution. In non-APOE4 carriers, the leading risk factors included high multimorbidity risk score, low overall self-rated health, low household income, long-term illness, high microalbumin in urine, high neutrophil count, and low greenspace percentage. Population attributable risk for these individual risk factors combined was 65.1%, and 85.8% in APOE4 and non-APOE4 carriers, respectively. For 20 risk factors including multimorbidity risk score, unhealthy lifestyle habits, and particulate matter air pollutants, their associations with incident dementia were stronger in non-APOE4 carriers. For only 2 risk factors (mother’s history of dementia, low C-reactive protein), their associations with incident all-cause dementia were stronger in APOE4 carriers.ConclusionsOur findings provide evidence for personalized preventative approaches to dementia/AD in APOE4 and non-APOE4 carriers. A mother’s history of dementia and low levels of C-reactive protein were more important risk factors of dementia in APOE4 carriers whereas leading risk factors including unhealthy lifestyle habits, multimorbidity risk score, inflammation and immune-related markers were more predictive of dementia in non-APOE4 carriers.

Monitoring Nitrogen Dioxide (NO2) in Environment of Ukraine based on Satellite Data

Air pollution (especially near industrial enterprises that are located mainly in densely populated regions) is one of the most significant problems of modern ecology. The purpose of this research is to study nitrogen dioxide air pollution over Ukraine, which has a negative impact on human health. As part of the research over the territory of Ukraine, the real planar distribution of nitrogen dioxide (NO2) as well as its local emissions (which make the main contribution to this distribution) were revealed using the materials of the remote sensing of the Earth from the AURA satellite. The results were calculated for the multi-year period of 2005 through 2021 and separately for 2022, which characterized the full-scale war in Ukraine and which made it possible to identify priority polluters; namely, industrial enterprises (thermal power plants, heavy metallurgy enterprises, etc.). For 17 years, the average value of NO2 was 160.78 · 102 molecules/mm2; in 2022, its concentration decreased to 126.93·109 molecules/mm2. The war manifested itself due to the shutdown of industrial enterprises, which were (and remain) priority polluters in Ukraine (particularly in large cities).

How does pollen production of allergenic species differ between urban and rural environments?

Pollen production is one plant characteristic that is considered to be altered by changes in environmental conditions. In this study, we investigated pollen production of the three anemophilous species Betula pendula, Plantago lanceolata, and Dactylis glomerata along an urbanization gradient in Ingolstadt, Germany. We compared pollen production with the potential influencing factors urbanization, air temperature, and the air pollutants nitrogen dioxide (NO2) and ozone (O3). While we measured air temperature in the field, we computed concentration levels of NO2 and O3 from a land use regression model. The results showed that average pollen production (in million pollen grains) was 1.2 ± 1.0 per catkin of Betula pendula, 5.0 ± 2.4 per inflorescence of Plantago lanceolata, and 0.7 ± 0.5 per spikelet of Dactylis glomerata. Pollen production was higher in rural compared to urban locations on average for B. pendula (+ 73%) and P. lanceolata (+ 31%), while the opposite was the case for D. glomerata (- 14%). We found that there was substantial heterogeneity across the three species with respect to the association of pollen production and environmental influences. Pollen production decreased for all species with increasing temperature and urbanization, while for increasing pollutant concentrations, decreases were observed for B. pendula, P. lanceolata, and increases for D. glomerata. Additionally, pollen production was found to be highly variable across species and within species-even at small spatial distances. Experiments should be conducted to further explore plant responses to altering environmental conditions.

Assessment of Spatial and Temporal Variation in NO2 Levels over Tourist Reception Areas in Poland

Air quality in tourist reception areas can be a significant health concern. It also plays an increasingly important role when it comes to choosing tourist destinations. NO2 is a harmful gas that can cause an increased number of cancer or respiratory diseases. The development of satellite remote sensing techniques now enables a much broader spectrum of air quality analysis than mere point measurements at environment monitoring stations. In the study, the spatial diversity of nitrogen dioxide air pollution over tourist reception areas in Poland was assessed. The lowest pollution was found in national parks and tourist regions. The most polluted air was found in tourist reception areas located near industrial regions and large urban agglomerations. Temporal variation—annual and monthly—and spatial variation were determined (for the period 2019–2021). The highest concentrations, exceeding the WHO recommended value (40 μmol/m2), occurred in the winter and autumn. Low pollution was found in most reception areas in the summer (except cities). In 2020, due to restrictions related to the SARS-CoV-2 epidemic, the NO2 pollution decreased (10–20%). In the cold half of the year (October–April), NO2 concentrations greater than 40 μmol/m2 occurred for about 20% of national parks, 50% of health resorts, 30% of tourist regions, and 100% of provincial capitals.

Traffic-related air pollution is associated with spontaneous extremely preterm birth and other adverse perinatal outcomes

Although there is growing awareness of the relationship between air pollution and preterm birth, limited data exist regarding the relationship with spontaneous preterm birth and severe neonatal outcomes. This study aimed to examine the association between traffic-associated air pollution exposure in pregnancy and adverse perinatal outcomes including extremes of preterm birth, neonatal intensive care unit admissions, low birthweight, neonatal respiratory diagnosis, neonatal respiratory support, and neonatal sepsis evaluation. This was a retrospective cohort study of singleton pregnancies of patients residing in a metropolitan area in the southern United States. Using monitors strategically located across the region, average nitrogen dioxide concentrations were obtained from the Environmental Protection Agency Air Quality System database. For patients living within 10 miles of a monitoring station, average exposure to nitrogen dioxide was estimated for individual patients' pregnancy by trimester. Logistic regression models were used to assess the effect of pollutant exposure on gestational age at birth, indicated vs spontaneous delivery, and neonatal outcomes while adjusting for maternal age, self-reported race, parity, season of conception, diabetes mellitus, body mass index, registered Health Equity Index, and nitrogen dioxide monitor region. Adjusted odds ratios and 95% confidence intervals were calculated for an interquartile increase in average nitrogen dioxide exposure. Between January 1, 2013 and December 31, 2021, 93,164 patients delivered a singleton infant. Of these, 62,189 had measured nitrogen dioxide exposure during the pregnancy from a nearby monitoring station. Higher average nitrogen dioxide exposure throughout pregnancy was significantly associated with preterm birth (adjusted odds ratio, 1.94; 95% confidence interval, 1.77-2.12) and an increase in neonatal intensive care unit admissions, low birthweight infants, neonatal respiratory diagnosis, neonatal respiratory support, and neonatal sepsis evaluation. This relationship persisted for nulliparous patients and spontaneous preterm birth, and had a greater association with earlier preterm birth. In a metropolitan area, increased exposure to the air pollutant nitrogen dioxide in pregnancy was associated with spontaneous preterm birth and had a greater association with extremely preterm birth. A greater association with neonatal intensive care unit admissions, low-birthweight infants, neonatal respiratory diagnosis, neonatal respiratory support, and neonatal sepsis evaluation was found even in term infants.

Phenylalanine Residues Are Very Rapidly Damaged by Nitrate Radicals (NO3 ⋅) in an Aqueous Environment.

Kinetic studies revealed that nitrate radicals (NO3 ⋅), which are formed through reaction of the noxious air pollutants nitrogen dioxide (NO2 ⋅) and ozone (O3 ), very rapidly oxidize phenylalanine residues in an aqueous environment, with overall rate coefficients in the 108 -109 M-1 s-1 range. With amino acids and dipeptides as model systems, the data suggest that the reaction proceeds via a π-complex between NO3 ⋅ and the aromatic ring in Phe, which subsequently decays into a charge transfer (CT) complex. The stability of the π-complex is sequence-dependent and is increased when Phe is at the N terminus of the dipeptide. Computations revealed that the considerably more rapid radical-induced oxidation of Phe residues in both neutral and acidic aqueous environments, compared to acetonitrile, can be attributed to stabilization of the CT complex by the protic solvent; this clearly highlights the health-damaging potential of exposure to combined NO2 ⋅ and O3 .

The coupling of graphene, graphitic carbon nitride and cellulose to fabricate zinc oxide-based sensors and their enhanced activity towards air pollutant nitrogen dioxide

It is desirable but challenging to sense toxic nitrogen dioxide (NO2) for it has become one of the most prominent air pollutants. Zinc oxide-based gas sensors are known to detect NO2 gas efficiently, however, the sensing mechanism and involved intermediates structures remain underexplored. In the work, a series of sensitive materials, including zinc oxide (ZnO) and its composites ZnO/X [X = Cel (cellulose), CN (g-C3N4) and Gr (graphene)] have been comprehensively examined by density functional theory. It is found that ZnO favors adsorbing NO2 over ambient O2, and produces nitrate intermediates; and H2O is chemically held by zinc oxide, in line with the non-negligible impact of humidity on the sensitivity. Of the formed composites, ZnO/Gr exhibits the best NO2 gas-sensing performance, which is proved by the calculated thermodynamics and geometrical/electronic structures of reactants, intermediates and products. The interfacial interaction has been elaborated on for composites (ZnO/X) as well as their complexes (ZnO- and ZnO/X-adsorbates). The current study well explains experimental findings and opens up a way to design and unearth novel NO2 sensing materials.

The association of air pollution with fetal anomalies

Because the relationship between pollution and congenital anomalies is biologically plausible but not well explored, our aim was to examine the association between air pollution exposure in pregnancy and fetal anomalies within a publicly-insured, large inner-city population. We hypothesized that higher exposure to the air pollutant Nitrogen Dioxide (NO2) would be associated with a higher rate of major fetal anomalies.

Long-term exposure to nitrogen dioxide air pollution and breast cancer risk: A nested case-control within the French E3N cohort study

Nitrogen dioxide (NO2) is an important air pollutant due to its adverse effects on human health. Yet, current evidence on the association between NO2 and the risk of breast cancer lacks consistency. In this study, we investigated the association between long-term exposure to NO2 and breast cancer risk in the French E3N cohort study. Association of breast cancer risk with NO2 exposure was assessed in a nested case-control study within the French E3N cohort including 5222 breast cancer cases identified over the 1990–2011 follow-up period and 5222 matched controls. Annual mean concentrations of NO2 at participants’ residential addresses for each year from recruitment 1990 through 2011, were estimated using a land use regression (LUR) model. Multivariable conditional logistic regression models were used to compute odds ratios (ORs) and their 95% confidence intervals (CIs). Additional analyses were performed using NO2 concentrations estimated by CHIMERE, a chemistry transport model. Overall, the mean NO2 exposure was associated with an increased risk of breast cancer. In all women, for each interquartile range (IQR) increase in NO2 levels (LUR: 17.8 μg/m3), the OR of the model adjusted for confounders was 1.09 (95% CI: 1.01–1.18). The corresponding OR in the fully adjusted model (additionally adjusted for established breast cancer risk factors) was 1.07 (95% CI: 0.98–1.15). By menopausal status, results for postmenopausal women were comparable to those for all women, while no association was observed among premenopausal women. By hormone receptor status, the OR of estrogen receptor positive breast cancer = 1.07 (95% CI: 0.97–1.19) in the fully adjusted model. Additional analyses using the CHIMERE model showed slight differences in ORs estimates. The results of this study indicate an increased risk of breast cancer associated with long-term exposure to NO2 air pollution. Observing comparable effects of NO2 exposure estimated by two different models, reinforces these findings.

How do the stay-at-home (SAH) orders affect air quality? Evidence from the northeastern USA.

This paper examines whether the SAH orders, implemented in the USA from mid-March to late May 2020, improved air quality in the northeastern states. The estimates are based on panel data from the Environmental Protection Agency and an identification strategy that exploits the exogenous variation in the timing of the SAH orders. We find that the SAH orders reduced the concentrations of the air pollutants nitrogen dioxide ({textrm{NO}}_2) and carbon monoxide (CO), whose dominant source is motor vehicle emissions, by approximately 24% and 13%, respectively. The effects were larger for areas of high population density and areas near major roads. We also find that the reductions got smaller, and air pollution gradually approached normal levels, after the orders were lifted. This suggests that the air quality improvements were temporary.

Daily Satellite Observations of Nitrogen Dioxide Air Pollution Inequality in New York City, New York and Newark, New Jersey: Evaluation and Application.

Urban air pollution disproportionately harms communities of color and low-income communities in the U.S. Intraurban nitrogen dioxide (NO2) inequalities can be observed from space using the TROPOspheric Monitoring Instrument (TROPOMI). Past research has relied on time-averaged measurements, limiting our understanding of how neighborhood-level NO2 inequalities co-vary with urban air quality and climate. Here, we use fine-scale (250 m × 250 m) airborne NO2 remote sensing to demonstrate that daily TROPOMI observations resolve a major portion of census tract-scale NO2 inequalities in the New York City-Newark urbanized area. Spatiotemporally coincident TROPOMI and airborne inequalities are well correlated (r = 0.82-0.97), with slopes of 0.82-1.05 for relative and 0.76-0.96 for absolute inequalities for different groups. We calculate daily TROPOMI NO2 inequalities over May 2018-September 2021, reporting disparities of 25-38% with race, ethnicity, and/or household income. Mean daily inequalities agree with results based on TROPOMI measurements oversampled to 0.01° × 0.01° to within associated uncertainties. Individual and mean daily TROPOMI NO2 inequalities are largely insensitive to pixel size, at least when pixels are smaller than ∼60 km2, but are sensitive to low observational coverage. We statistically analyze daily NO2 inequalities, presenting empirical evidence of the systematic overburdening of communities of color and low-income neighborhoods with polluting sources, regulatory ozone co-benefits, and worsened NO2 inequalities and cumulative NO2 and urban heat burdens with climate change.

Mitigating nitrogen dioxide air pollution: The roles and effect of national smart city pilots in China

The impacts of smart city policy on environmental efficiency and pollution are widely studied. However, we know very little about the roles and effect of smart city policy in nitrogen dioxide (NO2) air pollution. Using Chinese city-level panel data, we investigate the impact of national smart city pilots on satellite-derived ground level NO2 concentrations by Difference-in-Differences method. The results show that the smart city policy is conductive to mitigating the NO2 concentrations in pilot cities, especially for the cities with large population, high administrative hierarchies and located in eastern China. In particular, the mitigation effect of first round smart city pilots is greater than the second and third rounds. The mechanisms of smart city policy mitigating NO2 concentrations is to optimize energy structure and advance treatment technology, rather than directly reduce fossil energy consumption. Therefore, smart city policy may be a win-win choice for developing countries to break the trade-off between air pollution and economic development.

Assessing the impact of long-term exposure to nine outdoor air pollutants on COVID-19 spatial spread and related mortality in 107 Italian provinces

This paper investigates the air quality in 107 Italian provinces in the period 2014–2019 and the association between exposure to nine outdoor air pollutants and the COVID-19 spread and related mortality in the same areas. The methods used were negative binomial (NB) regression, ordinary least squares (OLS) model, and spatial autoregressive (SAR) model. The results showed that (i) common air pollutants—nitrogen dioxide (NO2), ozone (O3), and particulate matter (PM2.5 and PM10)—were highly and positively correlated with large firms, energy and gas consumption, public transports, and livestock sector; (ii) long-term exposure to NO2, PM2.5, PM10, benzene, benzo[a]pyrene (BaP), and cadmium (Cd) was positively and significantly correlated with the spread of COVID-19; and (iii) long-term exposure to NO2, O3, PM2.5, PM10, and arsenic (As) was positively and significantly correlated with COVID-19 related mortality. Specifically, particulate matter and Cd showed the most adverse effect on COVID-19 prevalence; while particulate matter and As showed the largest dangerous impact on excess mortality rate. The results were confirmed even after controlling for eighteen covariates and spatial effects. This outcome seems of interest because benzene, BaP, and heavy metals (As and Cd) have not been considered at all in recent literature. It also suggests the need for a national strategy to drive down air pollutant concentrations to cope better with potential future pandemics.

Satellite observations of NO2 indicate legacy impacts of redlining in U.S. Midwestern cities

Redlining was a practice of financial discrimination in the mid-20th century in which banks refused loans or increased interest rates based on the grade of an applicant’s neighborhood as designated by the federally sponsored Home Owner’s Lending Commission (HOLC). The HOLC primarily graded neighborhoods from “A” (best) to “D” (hazardous) based on characteristics including the racial demographics and economic status of the residents, with neighborhoods with higher percentages of non-white and/or recent immigrant residents given lower grades; this and similar discriminatory practices can be traced to modern-day economic and environmental inequalities between neighborhoods. The legacy of redlining and related housing discrimination on modern-day urban air quality, which presents a significant threat to public health, remains an important issue in addressing environmental injustice in U.S. cities. In our study, we used remotely sensed estimates of the air pollutant nitrogen dioxide (NO2) collected with the TROPOMI satellite sensor, and shapefiles of redlined neighborhoods, to determine whether air quality varies among historic HOLC grades in 11 U.S. Midwestern metropolitan areas. This approach allowed us to test these tools for within-city analysis of NO2 for which high spatial and temporal resolution measurements are not often available, despite their importance for monitoring impacts on human health. We found that NO2 levels were as much as 16% higher in neighborhoods that were graded “D” compared to those graded “A” (as in Chicago), with the mean difference across all cities an increase of 7.3% ± 5.9%. These results present evidence of persistent modern-day inequality in urban air quality associated with historic discriminatory policies and should be used as an argument for government action improving air quality in neighborhoods that were poorly graded by the HOLC.

Oxidative Damage of Aliphatic Amino Acid Residues by the Environmental Pollutant NO3·: Impact of Water on the Reactivity.

The rate of oxidative damage of aliphatic amino acids and dipeptides by the environmental pollutant nitrate radical (NO3·) in an aqueous acidic environment was studied by laser flash photolysis. The reactivity dropped by a factor of about four for amino acid residues with secondary amide bonds and by a factor of up to nearly 20 for amino acid residues with tertiary amide bonds, compared with that in acetonitrile. According to density functional theory studies, the lower reactivity is due to protonation of the amide moiety, whereas in neutral water, hydrogen bonding with the amide should have little impact on the absolute reaction rate compared with that in acetonitrile. This finding can be rationalized by the high reactivity and broad reaction pattern of NO3·. Although hydrogen bonding involving the amide group raises the energies associated with some electron transfer processes, alternative low-energy pathways remain available so that the overall reaction rate is barely affected. The undiminished high reactivity of NO3· toward aliphatic amino acid residues in a neutral aqueous environment highlights the health-damaging potential of exposure to the combined air pollutants nitrogen dioxide (NO2·) and ozone (O3).

2D SnSe2 nanoflakes decorated with 1D ZnO nanowires for ppb-level NO2 detection at room temperature

The detection of air pollutant nitrogen dioxide (NO2) is of great importance arising from its great harm to the ecological environment and human health. However, the detection range of most NO2 sensors is ppm-level, and it is still challenging to achieve lower concentration (ppb-level) NO2 detection. Herein, 2D tin diselenide nanoflakes decorated with 1D zinc oxide nanowires (SnSe2/ZnO) heterojunctions were first reported by facile hydrothermal and ultra-sonication methods. The response of the fabricated SnSe2/ZnO sensor enhances 3.41 times on average compared with that of pure SnSe2 sensor to 50–150 ppb NO2 with a high detection sensitivity (22.57 ppm-1) at room temperature. In addition, the SnSe2/ZnO sensor has complete recovery, negligible cross-sensitivity, and small relative standard deviation (6.98%) during the 1 month sensing test, which can meet the requirements for NO2 detection in environmental monitoring. The enhanced NO2 sensing performance can be attributed to the n-n heterojunction constructed between SnSe2 and ZnO. The as-prepared sensor based on SnSe2/ZnO hybrid significantly promotes the development of the low detection limit of the NO2 sensor at room temperature.

Assessing the change of ambient air quality patterns in Jiangsu Province of China pre-to post-COVID-19

Following the outbreak of the novel coronavirus in early 2020, to effectively prevent the spread of the disease, major cities across China suspended work and production. While the rest of the world struggles to control COVID-19, China has managed to control the pandemic rapidly and effectively with strong lockdown policies. This study investigates the change in air pollution (focusing on the air quality index (AQI), six ambient air pollutants nitrogen dioxide (NO2), ozone (O3), sulphur dioxide (SO2), carbon monoxide (CO), particulate matter with aerodynamic diameters ≤10 μm (PM10) and ≤2.5 μm (PM2.5)) patterns for three periods: pre-COVID (from 1 January to May 30, 2019), active COVID (from 1 January to May 30, 2020) and post-COVID (from 1 January to May 30, 2021) in the Jiangsu province of China. Our findings reveal that the change in air pollution from pre-COVID to active COVID was greater than in previous years due to the government's lockdown policies. Post-COVID, air pollutant concentration is increasing. Mean change PM2.5 from pre-COVID to active COVID decreased by 18%; post-COVID it has only decreased by 2%. PM10 decreased by 19% from pre-COVID to active COVID, but post-COVID pollutant concentration has seen a 23% increase. Air pollutants show a positive correlation with COVID-19 cases among which PM2.5, PM10 and NO2 show a strong correlation during active COVID-19 cases. Metrological factors such as minimum temperature, average temperature and humidity show a positive correlation with COVID-19 cases while maximum temperature, wind speed and air pressure show no strong positive correlation. Although the COVID-19 pandemic had numerous negative effects on human health and the global economy, the reduction in air pollution and significant improvement in ambient air quality likely had substantial short-term health benefits; the government must implement policies to control post-COVID environmental issues.