Concentrations Of Non-methane Hydrocarbons Research Articles

Non-methane hydrocarbons from integrated semiconductor manufacturing processes: Assessments of chemical footprints, emissions factors, and treatment efficiency

Non-methane hydrocarbons (NMHCs) are harmful chemicals produced from organic solvent use in industrial sectors. Wafer fabrication process from semiconductor fabs utilizes many organic solvents that could intensify NMHCs emissions. This study comprehensively assessed the Total NMHCs (TNMHCs) emissions from 141 exhaust pipes of 59 semiconductor fabs in Taiwan with regards to their concentrations, emission factors, treatment efficiency, and total chemical footprint (ChF) for human toxicity. Throughout three semi-processes of wafer fabrication, the raw emitted NMHCs concentrations were in the ranges of 3–131.25 ppm, 8–288 ppm, and 23–567 ppm for wafer cleaning (WC), photoresist stripping (PS), and photolithography (PL). The average untreated TNMHCs emissions rate was 0.2 ± 0.08 kg/h < 1.72 ± 0.09 kg/h < 2.55 ± 0.08 kg/h in the order of WC < PS < PL, whereas the average treated emissions rates were in the ranges of 0.09–0.10 kg/h. The estimated emission factors for wafer fabrication process were 0.30 ± 0.04 kg/kg, 0.07 ± 0.02 kg/piece, and 1.37 ± 0.11 kg/m2. Further assessment has found that zeolite rotary concentrator and regenerative thermal oxidations (ZRC + RTO) possess the highest overall performances for abating TNMHCs emission with efficiency ranges of 92.31–99.56% (n = 66). ZRC + RTO could produce outlet TNMHCs within the ranges of 2.94–5.56 ppm, which were lower than the upcoming revised emission standard of <14 ppm. ChF analysis of the estimated NMHCs species showed that PL had the largest untreated ChF, followed by PS, and WC of which the ChF were 15.72, 7.05, and 6.79 cases. The speciated ChF was dominated by acetone, methanol, and isopropyl alcohol from three semi-processes. The ChF analysis in this study could potentially become a supporting instrument for industrial sectors to determine the major contributing processes and chemicals with adverse impacts to human health.

Obtaining accurate non-methane hydrocarbon data for ambient air in urban areas: comparison of non-methane hydrocarbon data between indirect and direct methods

Abstract. Since non-methane hydrocarbons (NMHCs) include numerous species of volatile organic compounds (VOCs), they are the only indicators that can characterize the total amount of VOCs in ambient air. More than 90 % of NMHC instruments in the market use the indirect method for NMHC determination, utilizing a gas chromatograph to determine the concentrations of total hydrocarbons (THCs) and methane in air. However, we found indirect NMHC measurements incorrectly characterized the low NMHC concentrations in the urban air. These measurements were hindered by the uncertain changes in the errors associated with low THC concentrations, humidity and macroscopic substances (oxygen) in the atmosphere. In this study, we conducted intercomparisons between 10 instruments in the market using different operation principles; among these, two used the direct method, and eight used the indirect method. For the indirect method, experiments showed that when the NMHC concentration was 50 ppb C, the errors in the measurement results were 32 % (CH4) and 98 % (THC) when compared to theoretical values. The oxygen content in the sample gas directly affected the response of the THC. The effect of increased oxygen content on the analysis of oxygen-containing substances was more significant than that of the increase in hydrocarbon substances. The response of dry zero was blank, and the response value increased non-linearly with relative humidity (RH). RH had a great impact on low NMHC concentrations of nearly 50 %. For the direct method, although various flow designs were applied for different instruments, the results indicated that they generally showed lower interference and higher accuracy for the ambient NMHC measurements. With the online direct methods, we obtained more reliable data and characteristics for low-concentration NMHCs in downtown Shanghai. The median of hourly data was 163.1 ppb C, and the highest ratio of the maximum and minimum concentrations of NMHCs reached 9.56 in a single day.

Data mining from process monitoring of typical polluting enterprise.

With the increasing volume of environmental monitoring data, extracting valuable insights from multivariate time series sensor data can facilitate comprehensive information utilization and support informed decision-making in environmental management. However, there is a dearth of comprehensive research on multivariate data analysis for process monitoring in typical polluting enterprises. In this study, an artificial neural network model based on back-propagation algorithm (BP-ANN) was developed to predict the wastewater and exhaust gas emissions using IoT data obtained from process monitoring of a typical polluting enterprise located in Taizhou, Zhejiang Province, China. The results indicate that the model constructed has a high predictive coefficient of determination (R2) with values of 0.8510, 0.9565, 0.9561, 0.9677, and 0.9061 for chemical oxygen demand (COD), potential of hydrogen (pH), electrical conductivity (EC), flue gas emission (FGE), and non-methane hydrocarbon concentration (NMHC) respectively. For the first time, the variable importance measure (VIM)-assisted BP-ANN was employed to investigate the internal and external correlations between wastewater and exhaust gas treatment, thereby enhancing the interpretability of mapping features in the BP-ANN model. The predicted errors for pH and FGE have been demonstrated to fall within the range of - 0.62 ~ 0.30 and - 0.21 ~ 0.15 m3/s, respectively, with average relative errors of 1.05% and 9.60%, which is advantageous in detecting anomalous data and forecasting pollution indicator values. Our approach successfully addresses the challenge of segregating data analysis for wastewater disposal and exhaust gas disposal in the process monitoring of polluting enterprises, while also unearthing potential variables that significantly contribute to the BP-ANN model, thereby facilitating the selection and extraction of characteristic variables.

Non-methane hydrocarbon characteristics and their ozone and secondary organic aerosol formation potentials and sources in the plate and logistics capital of China

Non-methane hydrocarbon (NMHC) is an important precursor of ozone (O3) and secondary organic aerosols (SOAs). As the plate and logistics capital of China, the characteristics and sources of NMHC in Linyi may differ from other areas. Therefore, to understand NMHC pollution characteristics and guide future control strategies, samples were collected from April to October 2021–2022 in Linyi to analysis NMHC concentration levels, ozone formation potential (OFP), secondary organic aerosol formation potential (SOAFP), and sources in different seasons. The NMHC concentrations in spring and summer were 100.1 ± 29.5 and 98.4 ± 31.7 μg/m3, respectively, higher than in autumn (83.7 ± 25.1 μg/m3) due to the re-outbreak of COVID-19 in Linyi in autumn. However, no difference was seen in the dominant NMHC contributors—oxygenated volatile organic compounds (OVOCs), alkane, and aromatics—among different seasons. Both the OFP and SOAFP of NMHC showed obvious seasonal variations with summer > spring > autumn. Promoting the use of non-formaldehyde adhesive and reducing 1, 3-diethylbenzene in organic synthesis are crucial for alleviating O3 and SOA pollution, respectively. Vehicle related, liquefied petroleum gas (LPG), natural gas (NG), solvent use, and the plate industry were the main NMHC sources in Linyi. The contribution of vehicle related and LPG/NG in autumn (13.7%) was lower than in spring (32.7%) and summer (29.4%), while the contribution of combustion in summer (5.7%) was lower than in spring (15.6%) and autumn (17.9%), consistent with the results of species-specific diagnostic ratios. Regional pollution transport was also analyzed. Although we encourage joint prevention and control regarding air pollution, the main areas of joint prevention and control should be different in different seasons, which can reduce adverse human effects and the consumption of material and financial resources.

An unneglected source to ambient brown carbon and VOCs at harbor area: LNG tractor truck

The ambient air quality of harbors area in Asia is commonly more polluted compared to other continents. The airborne pollutant is directly or indirectly related to a significant impact of traffic emissions. This study for the first time assessed the impacts on brown carbon (BrC) and volatile organic compounds (VOCs) from in-port liquid natural gas (LNG) tractor truck at harbor areas, via conducting real-time monitoring of VOCs characteristic and sampling for ambient air at a harbor (named as W harbor) in Shanghai, China, collecting emissions of in-port LNG tractor truck and miniCast in laboratory, as well as statistics of external container diesel trucks in the port for further validation. HPLC/DAD/Q-Tof MS was adopted for sample analysis. Results showed that many CHO compounds were associated with vehicle exhausts. Among of them, aliphatic CHO compounds with low degree of unsaturation were identified as fatty acids and fatty acid methyl esters extensively existing in fuel combustion emissions. And non-aliphatic CHO compounds characterized by low O/C ratios (<0.17) identified for the harbor air came from the emissions of in-port LNG power trucks with low-speed driving and idling. The ambient average non-methane total hydrocarbons (NMHC) concentration (0.59 ppm) at W harbor was much greater than that for other areas in Shanghai. The higher ratios of toluene/benzene (3.30) and m/p-xylene/ethylbenzene (3.11) observed at W harbor implied instead of external container diesel trucks, the dominating contributing of internal LNG tractor trucks to ambient VOCs cannot be neglected. This study concluded that LNG is not as clean as it was expected. The LNG-fueled vehicles can produce strong light-absorption chromophores as well as high concentration of VOCs.

Long-term field calibration of low-cost metal oxide VOC sensor: Meteorological and interference gas effects

This study aimed to evaluate the performance of the Sensirion SGP30 MOS (metal oxide semiconductor) VOC sensors (SMVSs) for a long sampling period (10–12 months) at different ambient air monitoring stations (AQMSs). In the field tests, temperature (T), relative humidity (RH), carbon monoxide (CO) concentration, and non-methane hydrocarbons (NMHC) concentrations were found to be the crucial parameters influencing the sensor readings. A multiple linear regression (MLR) calibration model using hourly T, RH, CO, and VOC values as parameters was developed at Zhongming (ZM) station and validated at Hsinchu (HC) and Tainan (TN) stations. After calibration, the SMVS performance was improved significantly with the decrease of mean normalized bias (MNBs) and mean normalized errors (MNEs) of hourly-average data from +228 to 473% to ±25.9% and 231–473%–47.2%, respectively based on the reference NMHC values in the AQMSs. For ambient NMHC concentrations higher than 100 ppbv, the MLR-calibrated results were further improved with MNBs (MNEs) less than ±20% (28.3%). The correlation between calibrated sensor data and reference data was enhanced significantly with the R2 values increasing from 0.27 to 0.50 to 0.65–0.78 at three stations. Therefore, these well-calibrated sensors can become viable tools for many purposes including hotspot identification and characterization, and personal exposure study (MNE<30%).

Development of a Long-Term Sampling Method for Determination of NMHCs in Indoor Air.

Vapor intrusion is detrimental for indoor air quality. One of the most common sources of vapor intrusion is soil contaminated with petroleum hydrocarbons. To evaluate the long-term risk from individual exposure to hydrocarbons it is necessary to measure quantitively and reliably an average concentration level of individual pollutants on a monthly or yearly basis. Temporal variability of vapor intrusion from hydrocarbons poses a significant challenge to determination of average exposure and there is a need for reliable long-term integrative sampling. To this end, an analytical method for determination of 10 selected nonmethane hydrocarbons (NMHCs), including hexane, heptane, octane, decane, benzene, toluene, ethyl-benzene, m,p-xylene, o-xylene, and naphthalene, sampled on active triple-bed tubes filled with Carbograph 2, Carbograph 1, and Carboxen 1003 adsorbents was developed and validated. Extensive laboratory studies proved the absence of breakthrough at 50% HR and ambient temperature for experiments lasting up to 28 days and established a safe sampling time/volume of 20 days/114 L when sampling at a low flow rate of around 4 mL min-1. In addition, the developed method includes detailed uncertainty calculations for determination of concentrations. Finally, the method was tested by measuring NMHC concentrations in indoor air at a former industrial site during a 2-month-long field campaign in Lyon. The results of the field campaign suggest that 4-week integrated concentration measurements can be achieved by using active sampling on triple-bed tubes at 4.5 mL min-1.

Distribution characteristics and environmental effects of non-methane hydrocarbons in the East China Sea

Non-methane hydrocarbons (NMHCs) are important reactive compounds in the atmosphere which are crucial to the formation of ozone (O3) and secondary organic aerosol (SOA). In this study, the distribution characteristics, sea-to-air fluxes, and environmental effects of NMHCs were investigated in the East China Sea during spring and autumn. Affected by abundant nutrients and dissolved organic matter in the coastal area, NMHCs concentrations inshore were higher than those offshore. The mean concentrations of ethane, ethene, propane, propene, and isoprene were 5.1, 3.8, 6.0, 2.3, and 4.0 times higher in spring than autumn, respectively. In spring, the higher isoprene concentrations might have been due to the higher phytoplankton biomass and outbreak of dinoflagellates, while elevated concentrations of other NMHCs were primarily due to photochemical processes associated with high level of solar radiation. Influenced by terrestrial input and atmospheric chemical reactions, atmospheric concentrations of NMHCs were significantly higher in autumn than in spring. The mean concentrations of ethane, ethene, propane, propene, and isoprene were 221 ± 92.4, 182 ± 112, 198 ± 184, 46.4 ± 25.4, and 7.0 ± 2.9 pptv in spring, and 1090 ± 353, 655 ± 519, 701 ± 329, 476 ± 388, and 35.0 ± 23.2 pptv in autumn, respectively. The mean sea-to-air fluxes of the five NMHCs were 132 ± 126, 658 ± 591, 123 ± 128, 93.4 ± 89.0, and 120 ± 98.6 nmol m−2 d−1 in spring and 31.1 ± 25.9, 352 ± 212, 36.5 ± 40.5, 71.2 ± 43.9, and 78.6 ± 64.8 nmol m−2 d−1 in autumn, respectively. In addition, according to the environmental effects of NMHCs, alkenes exhibited higher atmospheric chemical reactivity and were the major contributors to O3 and SOA formation.

Drying of Chinese medicine residues (CMR) by hot air for potential utilization as renewable fuels: drying behaviors, effective moisture diffusivity, and pollutant emissions.

The online version contains supplementary material available at 10.1007/s13399-022-03722-4.

Spatial characterization of HCHO and reapportionment of its secondary sources considering photochemical loss in Taiyuan, China

Formaldehyde (HCHO) plays an important role in atmospheric ozone (O3) formation. To accurately identify the sources of HCHO, carbonyls and volatile organic compounds (VOCs) were measured at three urban sites (Taoyuan, TY-U; Jinyuan, JY-U; Xiaodian, XD-U) and a suburban site (Shanglan, SL-B) in Taiyuan during a high O3 period (from July 20 to August 3, 2020). The average mixing ratio of HCHO at XD-U (8.1 ± 2.8 ppbv) was comparable to those at TY-U (7.4 ± 2.1 ppbv) and JY-U (7.0 ± 2.3 ppbv) but higher (p < 0.01) than that at SL-B (4.9 ± 2.3 ppbv). HCHO contributed to 54.3–59.9 % of the total ozone formation potentials (OFPs) of non-methane hydrocarbons (NMHCs) at four sites. The diurnal variation of HCHO concentrations reached a peak value at 12:00–15:00, which may be attributed to the strong photochemical reaction. To obtain more accurate source results of HCHO under the condition of photochemical loss, the initial concentrations of NMHCs were estimated based on photochemical age parameterization and incorporated into the positive matrix factorization (PMF) model (termed IC-PMF). According to the IC-PMF results, secondary formation (SF) contributed the most to HCHO at XD-U (35.6 %) and SL-B (25.1 %), whereas solvent usage (SU) (40.9 %) and coking sources (CS) (36.0 %) were the major sources at TY-U and JY-U, respectively. Compared to the IC-PMF, the conventional PMF analysis based on the observed data underestimated the contributions of SU (100.5–154.2 %) and biogenic sources (BS) (28.5–324.7 %). Further reapportionment of secondary HCHO by multiple linear regression indicated that SU dominated the sources of HCHO at SL-B (28.3 %) and TY-U (41.7 %), while industrial emissions (IE) and CS contributed the most to XD-U (26.6 %) and JY-U (43.0 %) in Taiyuan from north to south, respectively.

Long-term ambient hydrocarbon exposure and incidence of urinary bladder cancer

Particulate matter and volatile organic compounds, including total hydrocarbons (THCs), are major ambient air pollutants. Primary nonmethane hydrocarbons (NMHCs) originate from vehicle emissions. The association between air pollution and urinary bladder cancer (UBC) is debatable. We investigated whether long-term exposure to ambient hydrocarbons increases UBC risk among people aged ≥ 20 years in Taiwan. Linkage dataset research with longitudinal design was conducted among 589,135 initially cancer-free individuals during 2000–2013; 12 airborne pollutants were identified. Several Cox models considering potential confounders were employed. The study outcomes were invasive or in situ UBC incidence over time. The targeted pollutant concentration was divided into three tertiles: T1/T2/T3. The mean age of individuals at risk was 42.5 (SD 15.7), and 50.5% of the individuals were men. The mean daily average over 10 years of airborne THC concentration was 2.25 ppm (SD 0.13), and NMHC was 0.29 ppm (SD 0.09). Both pollutants show long-term monotonic downward trend over time using the Mann–Kendall test. There was a dose-dependent increase in UBC at follow-up. UBC incidence per 100,000 enrollees according to T1/T2/T3 exposure to THC was 60.9, 221.2, and 651.8, respectively; it was 170.0/349.5/426.7 per 100,000 enrollees, corresponding to T1/T2/T3 exposure to NMHC, respectively. Without controlling for confounding air pollutants, the adjusted hazard ratio (adj.HR) was 1.83 (95% CI 1.75–1.91) per 0.13-ppm increase in THC; after controlling for PM2.5, adj.HR was even higher at 2.09 (95% CI 1.99–2.19). The adj.HR was 1.37 (95% CI 1.32–1.43) per 0.09-ppm increase in ambient NMHC concentration. After controlling for SO2 and CH4, the adj.HR was 1.10 (95% CI 1.06–1.15). Sensitivity analyses showed that UBC development risk was not sex-specific or influenced by diabetes status. Long-term exposure to THC and NMHC may be a risk factor for UBC development. Acknowledging pollutant sources can inform risk management strategies.

Characteristics, secondary transformation and odor activity evaluation of VOCs emitted from municipal solid waste incineration power plant

Volatile organic compounds (VOCs) emitted from municipal solid waste incineration power plant (MSWIPP) plays a significant role in the formation of O3 and PM2.5 and odor pollution. Field test was performed on four MSWIPPs in an area of the North China Plain. Nonmethane hydrocarbons (NMHCs) and 102 VOCs were identified and quantified. Ozone formation potential (OFP), secondary organic aerosol formation potential (SOAFP), and odor activity of the detected VOCs were evaluated. Results showed that the average concentration of NMHCs and VOCs were 1648.6 ± 1290.4 μg/m3 and 635.3 ± 588.8 μg/m3, respectively. Aromatics (62.1%), O–VOCs (16.0%), and halo hydrocarbons (10.0%) were the main VOCs groups in the MSWIPP exhaust gas. VOCs emission factor of MSWIPP was 2.43 × 103 ± 2.27 × 103 ng/g-waste. The OFP and SOAFP of MSWIPP were 960.18 ± 2158.17 μg/m3 and 1.57 ± 3.38 μg/m3, respectively. Acrolein as the dominant VOC species was the major odor contributor with a percentage of odor contribution of 65.9%. Benzene and 1,2,4-trimethylbenzene as the dominant VOC species were the main contributors of O3 formation potentials, in which 1,2,4-trimethylbenzene was also the main contributors of SOA formation potential.

Ozone pollution in the plate and logistics capital of China: Insight into the formation, source apportionment, and regional transport

As the logistics and plate capital of China, the sources and regional transport of O3 in Linyi are different from those in other cities because of the significant differences in industrial structure and geographical location. Twenty-five ozone pollution episodes (OPEs, 52 days) were identified in 2021, with a daily maximum 8-h moving average O3 concentration (O3-MDA8) of 184.5 ± 22.5 μg/m3. Oxygenated volatile organic compounds (OVOCs) and aromatics were the dominant contributors to ozone formation potential (OFP), with contributions of approximately 23.5–52.7% and 20.0–40.8%, respectively, followed by alkenes, alkanes, and alkynes. Formaldehyde, an OVOC with high concentrations emitted from the plate industry and vehicles, contributed the most to OFP (22.7 ± 5.5%), although formaldehyde concentrations only accounted for 9.4 ± 2.7% of the total non-methane hydrocarbon (NMHC) concentrations. The source apportionment results indicated that the plate industry was the dominant O3 contributor (27.0%), followed by other sources (21.6%), vehicle-related sources (18.0%), solvent use (16.9%), liquefied petroleum gas (LPG)/natural gas (NG) (8.8%), and combustion sources (7.7%). Therefore, there is an urgent need to control the plating industry in Linyi to mitigate O3 pollution. The backward trajectory, potential source contribution function (PSCF), and concentration weighted trajectory (CWT) models were used to identify the air mass pathways and potential source areas of air pollutants during the OPEs. O3 pollution was predominantly affected by air masses that originated from eastern and local regions, while trajectories from the south contained the highest O3 concentrations (207.0 μg/m3). The potential source area was from east and south Linyi during the OPEs. Therefore, it is critical to implement regional joint prevention and control measures to lower O3 concentrations.

Diurnal variation and source analysis of NMHCs at a background site of Nam Co (4,730 m a.s.l.) in the interior area of Tibetan Plateau

As the highest plateau in the world, the atmospheric environment of the Tibetan Plateau (TP) has a significant influence on the continental and global climate. The non-methane hydrocarbon (NMHC) characteristics at the background site Nam Co (4730 m a.s.l.) on the TP were investigated based on the concentration characteristics, diurnal variations, emission source identification, and transport pathways in the summer of 2020. The concentration of NMHC at the sampling site was 3408 pptv, which was lower than most of global background sites. The diurnal variations in the NMHC concentration at the sampling site were higher at night and noon and lower in the morning and afternoon, which was quite different from that in urban areas. Positive matrix factorization (PMF) and HYSPLIT models were used to identify the NMHC emission sources. The PMF model identified regional transport (40.2%), biomass burning (23.6%), vehicle emissions (22.0%), and biogenic sources (14.2%) as the predominant NMHC sources. The HYSPLIT model indicated the air masses over the sampling site could be clustered in three directions. The analysis of the potential source contribution function (PSCF) and concentration-weighted trajectory (WCWT) indicated the NMHC concentration at the sampling site was primarily influenced by air masses from the southern Tibet. The health risk assessment signified the benzene levels were high enough to cause a potential cancer risk during the sampling period. Research on the NMHC characteristics of background sites could provide the basis for studying the NMHC transport pathway between regions and the global atmospheric motions.

Variability and sources of NMHCs at a coastal urban location in the Piraeus Port, Greece

Ambient concentrations and sources of non-Methane Hydrocarbons (NMHCs) with 6–9 carbon atoms were investigated at an industrialized coastal location within the Port of Piraeus in Greece. Measurements were performed for a yearlong period during 2019 by means of an automated gas chromatograph with flame ionization detector (GC-FID). N-Hexane registered the highest annual mean concentration, followed by toluene and benzene, whereas all compounds presented important day to day variability, with an enhancement in summer. The seasonal diurnal cycles were characterized by strong morning peaks, especially in summer. The night-time maxima were less pronounced during the warm period, by almost 50% relative to the morning ones. On the contrary, during winter night-time, the combined impact of emissions and the shallow boundary layer was reflected on the night-time peaks. The area seems to be affected mainly by local land emission sources, whereas temperature possibly triggers evaporation processes, as indicated by comparisons with nearby traffic and urban background sites. The enhanced NMHCs concentration, in spite of increased ventilation coefficients during the summer, indicated again the impact of local emission sources. This was also highlighted by means of Positive Matrix Factorization (PMF) modeling. Three PMF factors were identified, quantified and supported by supplementary seasonal runs during short-term campaigns. Fugitive emissions were recognized as the main source, contributing more than 70% of total NMHCs year-round, while the input of emissions associated with traffic and diesel combustion was almost equal (13% and 15%, respectively).

Acute effects of ambient non-methane hydrocarbons on cardiorespiratory hospitalizations: A multicity time-series study in Taiwan

BackgroundFew environmental epidemiological studies and no large multicity studies have evaluated the acute short-term health effects of ambient non-methane hydrocarbons (NMHC), the essential precursors of ground-level ozone and secondary organic aerosol formation. ObjectiveWe conducted this multicity time-series study in Taiwan to evaluate the association between airborne NMHC exposure and cardiorespiratory hospital admissions. MethodsWe collected the daily mean concentrations of NMHC, fine particulate matter (PM2.5), ozone (O3), weather conditions, and daily hospital admission count for cardiorespiratory diseases between 2014 and 2017 from eight major cities of Taiwan. We applied an over-dispersed generalized additive Poisson model (GAM) with adjustment for temporal trends, seasonal variations, weather conditions, and calendar effects to compute the effect estimate for each city. Then we conducted a random-effects meta-analysis to pool the eight city-specific effect estimates to obtain the overall associations of NMHC exposure on lag0 day with hospital admissions for respiratory and circulatory diseases, respectively. ResultsOn average, a 0.1-ppm increase of lag0 NMHC demonstrated an overall 0.9% (95% CI: 0.4–1.3%) and 0.8% (95% CI: 0.4–1.2%) increment of hospital admissions for respiratory and circulatory diseases, respectively. Further analyses with adjustment for PM2.5 and O3 in the multi-pollutant model or sensitivity analyses with restricting the NMHC monitoring from the general stations only confirmed the robustness of the association between ambient NMHC exposure and cardiorespiratory hospitalizations. ConclusionOur findings provide robust evidence of higher cardiorespiratory hospitalizations in association with acute exposure to ambient NMHC in eight major cities of Taiwan.

Spatiotemporal Variations in the Content of Pollutants in the Moscow Air Basin and Their Emissions

The location of Moscow on a plain within higher latitudes when compared to other megacities creates conditions for the chemical transformation of pollutants in the urban atmosphere and their transport and accumulation. Observational data on surface concentrations of NO, NO2, CO, CH4, O3, nonmethane hydrocarbons (NMHCs), and aerosols (PM10), which were obtained at the Moscow Ecological Monitoring (MEM) network from 2005 to 2020, have been processed and analyzed. Both temporal and spatial parameters characterizing the dynamics of atmospheric pollution of Moscow’s air basin have been calculated. It is noted that the content of most pollutants in the urban air has decreased due to the renewal of the vehicle fleet; the introduction of restrictions on the entry of freight transport in the city; and the modernization of industrial enterprises, treatment facilities, and the gas transmission system. Significant negative trends have been obtained for NMHCs, CO, NOx, and PM10 (4.3, 4.0, 2.6, and 1.7% y–1, respectively). An insignificant negative trend has been obtained for O3 and no negative trend has been found for CH4. Total emissions from urban sources of substances determining the air quality have been calculated. Their values also manifest negative trends. The content of ozone almost did not change within such a long period, which suggests a weak sensitivity of the oxidizing properties of the Moscow atmosphere and the rate of ozone generation to variations in the atmospheric content of nitrogen radicals and their high sensitivity to volatile organic compounds.

Decrease of the recovery rate of light non-methane hydrocarbons by interference of air oxygen in a measurement of non-methane hydrocarbon concentration under air

Decrease of the recovery rate of light non-methane hydrocarbons by interference of air oxygen in a measurement of non-methane hydrocarbon concentration under air

Association of exposure to hydrocarbon air pollution with the incidence of atopic dermatitis in children

BackgroundThere is growing evidence suggesting that air pollution may act as an important environmental risk factor in the development and aggravation of childhood atopic dermatitis (AD).MethodsWe collected data from the Taiwan National Health Insurance (NHI) research database and linked the data to the Taiwan Air Quality-Monitoring Database. From January 1, 2000 to December 31, 2012; children aged below 18 years were selected from the database and followed longitudinally until the diagnosis of AD, withdrawal from the NHI, or December 31, 2012. Children with missing data or those diagnosed with AD before enrolment in this study were excluded. We measured the incidence rate and hazard ratios (HRs) for AD and stratified them by quartiles (Q1–Q4) of air pollutant concentration. Multivariable Cox proportional hazards models were also applied by adjusting for age, sex, monthly income, and level of urbanization.ResultsWhen compared with the concentrations of pollutants in the Q1 quartile, the adjusted HR for AD increased with an increase in the exposure concentrations of total hydrocarbons (THCs), non-methane hydrocarbons (NMHCs), and methane (CH4) from 1.65 (95% confidence interval [CI]: 1.47–1.84) to 10.6 (95% CI: 5.85–7.07), from 1.14 (95% CI: 1.06–1.24) to 2.47 (95% CI: 2.29–2.66), and from 1.70 (95% CI: 1.52–1.89) to 11.9 (95% CI: 10.8–13.1), respectively. Patients exposed to higher levels of THCs, NMHCs, and CH4 exhibited greater incidence rates of childhood AD.ConclusionsThe present study demonstrated that exposure to higher concentrations of THCs, NMHCs, and CH4 were associated with an increased risk of childhood AD.

Simulation of O3 and NOx in São Paulo street urban canyons with VEIN (v0.2.2) and MUNICH (v1.0).

We evaluate the performance of the Model of Urban Network of Intersecting Canyons and Highways (MUNICH) in simulating ozone (O3) and nitrogen oxides (NOx) concentrations within the urban street canyons in the São Paulo metropolitan area (SPMA). The MUNICH simulations are performed inside the Pinheiros neighborhood (a residential area) and Paulista Avenue (an economic hub), which are representative urban canyons in the SPMA. Both zones have air quality stations maintained by the São Paulo Environmental Agency (CETESB), providing data (both pollutant concentrations and meteorological) for model evaluation. Meteorological inputs for MUNICH are produced by a simulation with the Weather Research and Forecasting model (WRF) over triple-nested domains with the innermost domain centered over the SPMA at a spatial grid resolution of 1 km. Street coordinates and emission flux rates are retrieved from the Vehicular Emission Inventory (VEIN) emission model, representing the real fleet of the region. The VEIN model has an advantage to spatially represent emissions and present compatibility with MUNICH. Building height is estimated from the World Urban Database and Access Portal Tools (WUDAPT) local climate zone map for SPMA. Background concentrations are obtained from the Ibirapuera air quality station located in an urban park. Finally, volatile organic compound (VOC) speciation is approximated using information from the São Paulo air quality forecast emission file and non-methane hydrocarbon concentration measurements. Results show an overprediction of O3 concentrations in both study cases. NOx concentrations are underpredicted in Pinheiros but are better simulated in Paulista Avenue. Compared to O3, NO2 is better simulated in both urban zones. The O3 prediction is highly dependent on the background concentration, which is the main cause for the model O3 overprediction. The MUNICH simulations satisfy the performance criteria when emissions are calibrated. The results show the great potential of MUNICH to represent the concentrations of pollutants emitted by the fleet close to the streets. The street-scale air pollutant predictions make it possible in the future to evaluate the impacts on public health due to human exposure to primary exhaust gas pollutants emitted by the vehicles.