Aerosol Science and Engineering最新文献

Singrauli coal fields are air polluted in an industrial town in India. The contribution of anthropogenic activities to increased particulate matter (PM) in the study area has been calculated. The size-segregated PM was collected in 2016 and 2017 and carried out for morphological and composition analysis. PCA (principal component analysis) and PMF (positive matrix factorization) were applied to quantify for identification and apportionment of sources. Based on the study, biomass burning and vehicular emission were the primary source of particulate matter; and PCA and PMF identify the contribution of biomass burning, vehicular emission, mining activity, resuspended dust, secondary inorganic aerosols, and traffic-related emission as the major sources of particulate matter in Singrauli coalfield.

The objective of this study was to estimate the particle emission rates, human dose and retention from two arc welding processes and cutting of stainless steel. The two arc welding processes were Shielded Metal Arc Welding (SMAW) and Tungsten Inert Gas (TIG). In a simulated confined workspace of experimental chamber under controlled conditions, four different scenarios were considered, including the use of filtering face piece respirator (FFR), leaving or staying in the workspace after the emission. Deposited and retained dose in the respiratory tract was assessed for the different regions of the human respiratory tract using a dosimetry model (ExDoM2). The three investigated processes generated high particle number concentrations ranging from 2.4 to 3.6 × 10⁶ particles/cm³ and were the highest during TIG. Among all three processes, PM₁₀ concentrations from cutting reached the highest levels [11 and 22 (× 10³) μg/m³], while SMAW had the highest contribution of fine particles [~ 4.1 (× 10³) μg/m³], consisting mostly of PM_1–2.5. The examination of different scenarios revealed that there is only a slight difference in respect to deposited dose while staying in the workspace for the entire investigated time period (4 h) with or without use of Filtering Facepiece Respirator (FFR). It would be more beneficial in respect to deposited dose if the exposed subject was not wearing a FFR during the emission process and would leave the polluted workspace immediately after the emission period. In the first two scenarios (staying 4 h in the polluted workspace with and without FFR), both welding processes had higher cumulative deposited (~ 23%) and retained dose (~ 20%) in thoracic region compared to cutting (~ 9% and ~ 7%). These results demonstrate that even a short emission period can cause a considerable increase in concentrations of harmful respirable particles, thus increasing the human dose. The approach applied in this study could be used for the determination of personal exposure and dose to particles of known composition particularly in confined workspaces.

The size of human speech or cough droplets decides their air-borne transport distance, life span and virus infection risk. We have investigated the measurement accuracy of artificial saliva and saline droplet size for more effective COVID-19 infection control. A spray generator was used for polydisperse droplet generation and a special test chamber was designed for droplet measurement. Saline and artificial saliva were gravimetrically prepared and used to generate droplets. The droplet spray generator and the test chamber were circulated among four metrology institutes (NMC, CMS/ITRI, NIM and KRISS) for droplet size measurement and evaluation of deviations. The composition of artificial saliva was determined by measuring the mass fraction of the inorganic ions. The density of dried artificial saliva droplets was estimated using its composition and the density of each non-volatile component. The volume equivalent diameter (VED) of droplets have been measured by aerodynamic particle sizer (APS) and optical particle size spectrometer (OPSS). As a response to the COVID-19 pandemic, this is the first time that a comparative study among four metrology institutes has been conducted to evaluate the accuracy of saliva and saline droplet size measurement. For artificial saliva droplets measured by OPSS, the deviations from the reference VED (~ 4 μm) were below 5.3%. For saline droplets measured by APS, the deviations from the reference VED were below 10.0%. The potential droplet size measurement errors have been discussed. This work underscores the need for new reference size standards to improve the accuracy and establish traceability in saliva and saline droplet size measurement.

Wet removal is the primary method for the natural removal of atmospheric aerosol particles, and wet removal is a very complex process. According to the PM_2.5, PM₁₀, and meteorological data from 71 cities in China from 2016 to 2018, this study utilizes theoretical analysis methods based on the existing rainfall aerosol removal theory and real-time monitoring data to calculate the measured removal coefficient and theoretical removal coefficient for verification. According to the different rainfall intensities and rainfall times in Guilin, the measured value and the simulated value are verified, and the linear relationship obtained was Λ_s = 1.589 × 10^–5 + 0.609Λ_m, R² = 0.673, and the simulated value approximated to the measured value after correction. The same method was utilized to calculate the theoretical removal coefficient of polydisperse aerosols in 71 cities across the country, and the calculation parameters of the rainfall removal polydisperse aerosol model in different regions were modified.

PM_2.5/PM₁₀ ratio is essential for understanding particulate pollution’s severity and adverse effects on human beings as it reveals how long the particle will stay in the atmosphere and where it will deposit in the human respiratory tract. The present study focuses on the spatio-temporal variability of the PM_2.5/PM₁₀ ratio from nine sites (six in Delhi, one each in Amritsar, Varanasi and Kolkata) in the Indo-Gangetic Plain (IGP) during the last 3 years (2019–2021) before, during, and after the COVID-19 pandemic-induced lockdown in India. Robust statistics such as median and percentiles have been employed to avoid bias due to non-normal distributions. Considerable spatial and temporal variability was seen throughout the 3 years. Amritsar and one site in Delhi exhibited the least temporal variability in PM_2.5/PM₁₀ (~ 10%) annually. However, the highest average variation over the 3 years was ~ 28%, noticed for one site in Delhi. The PM_2.5/PM₁₀ ratio was high (~ 0.6 ± 0.1) during the post-monsoon (Oct–Dec) and winter (Jan–Feb) seasons. The PM_2.5/PM₁₀ ratio was low (~ 0.4 ± 0.1) in the monsoon season (June–Sep.) and pre-monsoon season (Mar–May). Conditional Bivariate Probability Function (CBPF) and Cluster Analysis using Hysplit data were done to assess the local and long-range source of pollutants arriving at a receptor location. The impact of wind speed and relative humidity on the PM_2.5/PM₁₀ ratio was also analysed. The results of this study would help establish an intricate policy framework for cities in the IGP.

The activities of artisans conducted regularly in automobile workshops have been observed to generate pollutants that are not limited to particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs). Thus, this research provided data on the quantification of PAHs coupled with the building of a predictive statistical model for the prediction of benzo[a]pyrene (BaP) in Benin City. The city was divided into four zones, namely North West (NW), North East (NE), South East (SE) and South West (SW), and a total of 180 representative samples were collected from artisans’ workshops in both wet (April to November) and dry (December to March) seasons using an Apex2IS Casella standard pump fitted with a conical inhalable sampling (CIS) head at a flow rate of 3.5L/min for 8 h. Meteorological parameters were collected simultaneously with the PM_2.5 (particles with an aerodynamic diameter of less than or equal to 2.5 µm)_. PAHs were extracted and quantified using Gas Chromatography (GC) fitted with a flame-ionization detection (FID). The annual average concentration of the total PAHs bound to PM_2.5 for the NW, NE, SE, and SW zone were 519.51 (638.78), 109.13 (169.16), 158.89 (178.40) and 77.65 (89.60) ng/m³ for both the wet and dry seasons, respectively. A generalized linear model (GLiM) was used to develop a prediction model for the prediction of (BaP) air concentrations in the NW zone. The results of the selected model among the five trained models obtained with data from NW sampling sites are R² = 0.792 and adjusted R² = 0.746 for model 1, with an overall p-value of 0.01. The proposed model established an approximation to estimate Benzo[a]pyrene (BaP) concentrations in the urban automobile workshops’ atmospheres with reasonable accuracy of 60–72%.

The present research aims to describe the measurement of the changes in air pollutants such as black carbon (BC), PM_2.5, and CO concentrations levels, and estimation of their source apportionment and health risk during normal period (NP) as well as lockdown period (LP) in Jamshedpur city. The urban atmospheric pollutants mostly BC, PM_2.5 and CO concentrations were observed gradual fall during LP. The averaged mass concentration of BC, PM_2.5 and CO was found about 38.46 ± 1.91 µgm⁻³, 176.55 ± 21.72 µgm⁻³, 840 ± 282 ppbv in NP and 9.68 ± 2.36 µgm⁻³, 42.86 ± 18.97 µgm⁻³, 175.88 ± 121.82 ppbv during LP, respectively. BC, PM_2.5, and CO concentrations were shown to be lower during LP as compared to NP. This may be because of prohibited of all human activities due to COVID-19 pandemic. The source apportionment analysis of BC indicated that the biomass burning (62.5%) contribution was high as compared to fossil fuel emission (37.5%) at LP. The air trajectory model showed that most of the air masses were coming from western part of India and also some fresh marine air masses were received at the located position. The health risk for respective health effects of CVM (cardiovascular mortality), LC (lung cancer), LBW (low birth weight), and PLEDSC (percentage lung function decrement of school-aged children) due to exposure to BC was evaluated as 9.76, 4.8, 8.59 and 19.59 PSC in NP and 8.35, 4.1, 7.35 and 16.77 PSC in LP.

Graphical abstract