Sudden short-term air pollution episode is now widely considered to harm human health. Previous research has found that firework activities rapidly raise the PM2.5 level in the ambient air. This study investigates the influence of Yanshuei Beehive Fireworks Festival on atmospheric PM2.5 from February 9th to 12th, 2017. The PM2.5 samples were gathered at 8 sampling sites around Yanshuei and Xinying before (background (B)), trial (T), during (D), and after (A) beehive firework display periods during the Yanshuei Beehive Fireworks Festival. The temporospatial differences of atmospheric PM2.5 before and after fireworks activities were explored. The atmospheric PM2.5 level in major activity areas was significantly higher from the background level in the trial and festival periods, and even after the activity. The study revealed that PM2.5 level reached the highest value of 327 µg m−3 at the major activity areas, which is 6.6 and 5.9 times those at upwind (49.8 µg m−3) and downwind (55.5 µg m−3) sites, respectively. Additionally, the T/B and D/B ratios were 3.01 and 7.19, respectively, around the major activity area. Conversely, the wind rose diagrams and contour lines of PM2.5 concentrations evaluated using Surfer 10.0 around the ambient air demonstrate that the atmospheric PM2.5 levels at Yanshuei and Xinying were similar to each other (35–45 µg m−3). However, the PM2.5 hardly diffused to distant places and accumulated in the local area around the boundary between Yanshuei and Xinying during the Beehive Fireworks Festival, since the wind speed was usually low or even stayed calm. The iso-concentration contour maps show that K+, Cl−, Mg2+, and NO3− are related to firework release during the festival.

Round-nozzle inertial impactors are widely used aerosol measuring instruments to characterize the mass and chemical composition of airborne aerosol particles as a function particle aerodynamic diameter. This article summarizes the most important design considerations with updated recommended design parameters taken from our review of published research articles and discusses some of the more common non-idealities seen in the operation and performance of inertial impactors. With this information, it is now possible to design a cascade impactor with near-ideal particle separation performance, and with stage cutpoints that can be predicted with excellent accuracy and verified experimentally using state-of-the-art calibration techniques.

Volatile organic compounds (VOCs) are air pollutants associated with health problem. Paints mixed with photocatalytic (PC) materials are considered to be effective in the removal of VOCs. Therefore, this investigation aimed to produce a novel visible induced photocatalyst component in paint. The synthesized photocatalysts (i.e., Ag-TiO2 and Fe-TiO2) were self-prepared by sol-gel method and further used to produce paints. The effects of the paints on VOC (i.e., acetone) degradation under the irradiation of visible light were tested in a batch PC reactor and an environmental chamber. In order to evaluate the control effect of VOCs using the paint, a si mulated test was conducted in a real room. The results of batch experiments showed that the degradation efficiencies of acetone by the paints were lower than that by the related photocatalysts. The paints made of 3% Fe-TiO2 and 1% Ag-TiO2 achieved the highest acetone degradation efficiency of 32.7 and 21.3%, respectively. The degradation test conducted in the environmental chamber indicated that the degradation efficiencies of acetone were 24.9, 46.2, and 32.4% for the paints made of TiO2, 3% Fe-TiO2 and 1% Ag-TiO2, respectively. It was evidently provided that the paint made of 3% Fe-TiO2 could effectively degrade organic pollutants in indoor environments.

In response to the COVID-19 pandemic in early 2020, Sri Lanka underwent a nationwide lockdown that limited motor vehicle movement, industrial operations, and human activities. This study analyzes the impact of COVID-19 lockdown on carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter (PM10, PM2.5) concentrations in two urban cities (Colombo and Kandy) in Sri Lanka, by comparison of data from the lockdown period (March to May 2020) with its analogous period of 2019 and 2021. The results showed that the percentage change of daytime PM10, PM2.5, CO, and NO2 concentration during the lockdown in Colombo (Kandy) is –42.3% (–39.5%), –46% (–54.2%), –14.7% (–8.8%) and –82.2% (–80.9%), respectively. In both cities, the response of NO2 to the lockdown was the most sensitive. In contrast, daytime O3 concentration in Colombo (Kandy) has increased by 6.7% (27.2%), suggesting that the increase in O3 concentration was mainly due to a reduction in NOx emissions leading to lower O3 titration by NO. In addition, daytime SO2 concentration in Colombo has increased by 22.9%, while daytime SO2 concentration in Kandy has decreased by −40%. During the lockdown period, human activities were significantly reduced, causing significant reductions in industrial operations and transportation activities, further reducing emissions and improving air quality in two cities. The results of this study offer potential for local authorities to better understand the emission sources, assess the effectiveness of current air pollution control strategies, and form a basis for formulating better environmental policies to improve air quality and human health.

In former days, research in science and technology was done in defined individual disciplines like physics or chemistry and often limited to the country of origin of the involved researchers. Nowadays, new research areas are often multidisciplinary, international and often transcontinental. This has caused an increasing interest of scientists and researchers in getting information about the ongoing activities around the world and eventually led to building international and interdisciplinary communities. The rise of a new discipline in science and research is usually accompanied by the foundation of corresponding professional organizations in order to promote scientific work in this field, to exchange information by organizing scientific conferences, supporting publications and to establish scientific education and teaching. Relevant markers of the development of associations are the number of members, the composition of the membership, the locations, hosts and participants of conferences, the quantity and main topics of papers presented as well as the language and the proceedings of the conferences.

This research focuses on the properties of near-ground fine particles (PM2.5), ultrafine particles (UFP), black carbon (BC), and polycyclic aromatic hydrocarbons (PAHs) in traffic area. The effects of street sweeping and washing on pollutant levels are evaluated. The X Road with sewage ditch was selected for the stationary samplings to determine the differences between the atmospheric PM2.5 mass concentration, their composition, and potential sources before/after street cleaning processes, as well as the effect of the sewage existence. Results show that there were certain reductions of PM2.5 after the street washing, especially for the road section with drainage ditch. The chemical mass balance model then pointed out the traffic contribution on PM2.5 significantly reduced on the downwind site (from 25.7% to 16.5%). Besides, the spatial distribution of the near-ground PM2.5, UFP, BC, and PAHs were monitored by a mobile platform on an appropriate long, straight, and not heavily traffic Road Y. The monitoring took place at 1 h-before, during washing/sweeping, at 1 h-after, at 1 d-after, at 2 d-after three cleaning strategies, including only sweeping, washing-before-sweeping, and sweeping-before-washing. The monitoring then mapped out the hot spot distribution of pollutants. The PM2.5 mass, UFP number, BC, and PAH concentrations before the street sweeping is 155 µg m−3, 1.2 × 104 # cm−3, BC 3633 ng m−3, and 36 ng m−3. The UFP number concentration of suspended particles after street washing had a trend to reduce, avoided the deterioration of air quality. The strategy, “sweeping-before-washing”, was the best operation method among three to suppress the UFP number concentration by 42%, while all three strategies could effectively reduce the PAH levels. The primary pollutants are more easily reduced by the street-cleaning process, while the secondary one did not.

Airborne transmission of respiratory viruses consists of three sequential steps: (1) release of respiratory fluids in the form of droplets from the nose and mouth of an infected person, (2) transport of the droplets through air, and (3) entry of the droplets into the nose and mouth of an uninfected individual. Talking, coughing, and sneezing emit droplets across a spectrum of sizes. The water in exhaled droplets begins to evaporate in air and, as a result, the droplets are reduced in size shortly after being emitted. Face masks are effective for capturing droplets just released from the nose and mouth. Studies indicate that more than 50% of community transmission of SARS-CoV-2 is from asymptomatic and pre-symptomatic cases. Use of face masks by the public can effectively reduce the chance of infected individuals unknowingly spreading the virus. In addition to being an effective device for source control, face masks can protect the wearers from inhaling virus-laden droplets. Cloth masks and disposable masks provide reasonable protection for the public, while surgical masks and N95 respirators give higher levels of protection as needed in healthcare settings. Made with varied materials, these masks have different structural characteristics. The collection efficiency of a face mask depends on droplet size, face velocity, and the structural characteristics of the mask. For a given mask, capturing droplets is more effective during exhalation than during inhalation. Pressure drop across the mask should be taken into consideration when selecting a face mask. The best face mask is the one that gives the highest collection efficiency with the least pressure drop. For an effective protection, a mask should fit the face properly. While face masks have proven adequate in reducing airborne transmission of SARS-CoV-2 infections, continuous improvement is needed to better prepare for future respiratory viral threats.

A detrended seasonal analysis on a 6-year (2013–2018) dataset of daily Particulate Matter (PM) concentration and meteorological parameters is performed to understand the spatio-temporal variation of PM and the seasonal influence of meteorological factors on PM pollution over 6 major urban cities of Bangladesh. Cross-correlation and multiple non-linear regression (MNLR) of air quality and meteorological data were used to explore the meteorology-PM interactions and their spatio-temporal variability. Meteorological influence on PM was found to be stronger in the southern part of the country relative to the northwestern part. MNLR analysis implied that meteorological parameters could explain up to 39% of daily PM variability during high pollution days. The deposition effect of relative humidity was prominent during the premonsoon season, while rainfall impact becomes dominant in the monsoon season, specifically in the northeastern region. Wind speed was observed to have a dilatory effect on PM variation, although wind seemed to carry sea aerosol in southern regions. In addition, the northwestern wind appeared to contribute to PM rise in most urban areas by carrying PM loading. In winter, the low temperature was found to favor PM accumulation, while in monsoon, high temperature causes PM rise, possibly by assisting atmospheric secondary aerosol formation. Solar radiation positively influenced atmospheric PM formation, and the influence was stronger in the northwestern region. It is shown that meteorological parameters influence the seasonal variability of PM, but the extent of this influence varies depending on temporal and regional factors.

This study investigated the temporospatial variation, chemical composition, and source resolution of fine particles (PM2.5) in the southeastern seas of the Taiwan Island. 24-hr PM2.5 was sampled simultaneously at two remote sites, the Green Island (West Pacific Ocean; WPO) and the Kenting Peninsula (northern Bashi Channel; BC), in four seasons. After sampling, the chemical fingerprints of PM2.5 were characterized and further applied to resolve the potential sources of PM2.5 and their contribution by using a receptor model on the basis of chemical mass balance (CMB), enrichment factor (EF), and backward trajectory simulation. It showed that PM2.5 concentrations in winter (10.8 µg m−3) and spring (12.0 µg m−3) (i.e., during the period of Asian Northeastern Monsoons; ANMs) were higher than those in summer (4.0 µg m−3) and fall (6.6 µg m−3). In terms of chemical composition of PM2.5, secondary inorganic aerosols (SIAs = NO3−, SO42–, and NH4+) (56.7–67.2%) were the dominant component of water-soluble ions (WSIs) in PM2.5, while crustal elements (Mg, Al, Ca, Fe, and K) (44.0–61.2%) dominated the metallic contents in PM2.5. High EF values (> 10) showed that V, Mn, Ni, Cu, and Zn were potentially contributed from anthropogenic sources. Moreover, organic carbon (OC) (0.6 µg m−3) was superior to elemental carbon (EC) (0.3 µg m−3) in PM2.5. The OC/EC ratios higher than 2.0 showed the potential chemical formation of secondary organic aerosols (SOAs) in the atmosphere in winter and spring. Trajectory simulation indicated that high PM2.5 concentrations were mostly originated from North and Central China, Japan islands, and Korea Peninsula. Major sources of PM2.5 resolved by CMB receptor modeling were ordered as: sea salts (19.9%) > fugitive dust (19.8%) > industrial boilers (oil-fired) (10.8%) > secondary sulfate (9.8%) > mobile sources (8.0%).

At present, filterable particulate matter (FPM) emissions from stable source flue gases are well controlled, and the more difficult to remove condensable particulate matter (CPM) has received much attention due to its environmental hazards. In this study, we built a cold electrode electrostatic precipitator (CE-ESP) and systematically investigated the removal efficiency of CPM from municipal solid waste incineration plant flue gas by CE-ESP under three different operating modes. The results showed that hydrocarbons, esters and aromatic compounds were the main organic substances in CPM. The CE-ESP had a significant contribution to the removal of SO42−, F−, Al, Ni, Cr, and Pb from CPM. In contrast, it had a less effective removal of NO3− and Ca in CPM. The CE-ESP was effective for removing esters in CPM. The removal efficiency of CE-ESP for CPM could reach 76%, and the removal efficiency of organic substance was higher than that of inorganic substance. It is demonstrated that the combination of thermophoretic force and electric field in CE-ESP intensifies the turbulent agglomeration process, and the diffusion force generated by the concentration field synergistically enhances the interparticle coagulation and agglomeration. This promotes the homogeneous condensation process of CPM and the heterogeneous condensation of CPM and FPM, which is conducive to the reduction of condensable particulate matter in flue gas and can provide a theoretical basis for practical application in engineering.