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2 pages, 148 KiB

Open AccessEditorial

Advances in Gaseous and Particulate Air Pollutants Measurement

by Kyung-Hwan Kim

Appl. Sci. 2023, 13(13), 7438; https://doi.org/10.3390/app13137438 - 23 Jun 2023

Viewed by 745

Abstract

In recent years, notable advancements have been achieved in the science of aerosol and precursor gas measurements as well as the techniques used to apply them [...] Full article

(This article belongs to the Special Issue Advances in Gaseous and Particulate Air Pollutants Measurement)

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19 pages, 2257 KiB

Open AccessArticle

Long-Term Trend of the Levels of Ambient Air Pollutants of a Megacity and a Background Area in Korea

by Na-Kyung Kim, Yong-Pyo Kim, Hye-Jung Shin and Ji-Yi Lee

Appl. Sci. 2022, 12(8), 4039; https://doi.org/10.3390/app12084039 - 16 Apr 2022

Cited by 11 | Viewed by 2162

Abstract

It is imperative to understand the changes of the levels of air pollutants in Northeast Asia with respect to the changes of the emissions of air pollutants. In this study, we analyzed long-term trends of both the chemical composition of fine particles and [...] Read more.

It is imperative to understand the changes of the levels of air pollutants in Northeast Asia with respect to the changes of the emissions of air pollutants. In this study, we analyzed long-term trends of both the chemical composition of fine particles and gaseous species in Seoul, a megacity, and Baengnyeong Island, a background area located in the Yellow Sea of Republic of Korea (South Korea) from 2012 to 2019. Long-term changes of the concentrations of air pollutants were analyzed using the Mann–Kendall trend test and Sen’s slope. Since the SO₂ emissions in this region have been significantly reduced during last decade, NO₃⁻ has become the major species of fine particles instead of SO₄²⁻. Seoul and Baengnyeong Island are rich in NH₄⁺ in the atmosphere, and due to the SO₂ emission reduction, the balance of ammonia–nitric acid–sulfuric acid has been changed, and the concentration of NO₃⁻ has increased. This trend is more obvious in Baengnyeong Island than Seoul due to the lower local emissions in Baengnyeong Island. As a result of this study, it is possible to confirm that concentrations of air pollutants and the majority of aerosols affecting PM2.5 concentrations in Northeast Asia have changed according to the changes in emissions in this region. Full article

(This article belongs to the Special Issue Advances in Gaseous and Particulate Air Pollutants Measurement)

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11 pages, 2113 KiB

Open AccessArticle

COVID-19 Lockdown in Belgrade: Impact on Air Pollution and Evaluation of a Neural Network Model for the Correction of Low-Cost Sensors’ Measurements

by Ivan Vajs, Dejan Drajic and Zoran Cica

Appl. Sci. 2021, 11(22), 10563; https://doi.org/10.3390/app112210563 - 10 Nov 2021

Cited by 6 | Viewed by 1982

Abstract

In this paper, we explore the impact of the COVID-19 lockdown in Serbia on the air pollution levels of CO, NO₂ and PM₁₀ alongside the possibility for low-cost sensor usage during this period. In the study, a device with low-cost sensors [...] Read more.

In this paper, we explore the impact of the COVID-19 lockdown in Serbia on the air pollution levels of CO, NO₂ and PM₁₀ alongside the possibility for low-cost sensor usage during this period. In the study, a device with low-cost sensors collocated with a reference public monitoring station in the city of Belgrade is used for the same period of 52 days in 2019 (pre-COVID-19 period), 2020 (COVID-19 lockdown) and 2021 (post-COVID-19 period). Low-cost sensors’ measurements are improved by using a convolutional neural network that applies corrections of the influence of temperature and relative humidity on the low-cost sensors. As a result of this study we have noticed a remarkable decrease in NO₂ (primarily related to traffic density), while on the other hand CO and PM₁₀, related to domestic heating sources and heating plants, showed constant or slightly higher levels. The obtained results are in accordance with other published work in this area. The low-cost sensors have shown a satisfactory correlation with the reference CO measurements during the lockdown, while the NO₂ and PM₁₀ measurements of 2020 were corrected using a convolutional neural network trained on meteorological and pollutant data from 2019. The results include an improvement of 0.35 for the R2 of NO₂ and an improvement of 0.13 for the R2 of PM₁₀, proving that our neural network model trained on data from 2019 can improve the performance of the sensor in the lockdown period in 2020. This means that our neural network model is very robust, as it exhibits good performance even in the case where training data from the prior year (2019) are used in the following year (2020) in very different environment circumstances—a lockdown. Full article

(This article belongs to the Special Issue Advances in Gaseous and Particulate Air Pollutants Measurement)

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17 pages, 3143 KiB

Open AccessFeature PaperArticle

Size-Segregated Particulate Mass and Carbonaceous Components in Roadside and Riverside Environments

by Muhammad Amin, Rizki Andre Handika, Rahmi Mulia Putri, Worradorn Phairuang, Mitsuhiko Hata, Perapong Tekasakul and Masami Furuuchi

Appl. Sci. 2021, 11(21), 10214; https://doi.org/10.3390/app112110214 - 31 Oct 2021

Cited by 17 | Viewed by 2673

Abstract

Air sampling for 12 h diurnal and nocturnal periods was conducted at two monitoring sites with different characteristics in Jambi City, Sumatra Island, Indonesia. The sampling was done at a roadside site and a riverside site from 2–9 August, and from 7–13 August [...] Read more.

Air sampling for 12 h diurnal and nocturnal periods was conducted at two monitoring sites with different characteristics in Jambi City, Sumatra Island, Indonesia. The sampling was done at a roadside site and a riverside site from 2–9 August, and from 7–13 August in 2019, respectively. A cascade air sampler was used to obtain information on the status, characteristics and behavior of airborne particles with a particular focus on the ultrafine fraction (PM_0.1). The number of light vehicles was best correlated with most PM size categories, while those of heavy vehicles and motorcycles with the 0.5–1 μm and with >10 μm for the nocturnal period, respectively. These findings suggest that there is a positive influence of traffic amount on the PM concentration. Using carbonaceous parameters related to heavy-vehicle emissions such as EC and soot-EC, HV emission was confirmed to account for the PM_0.1 fraction more clearly in the roadside environment. The correlation between OC/EC and EC for 0.5–1 μm particles indicated that biomass burning has an influence on both in the diurnal period. A possible transboundary influence was shown as a shift in the PM_0.1 fraction characteristic from “urban” to “biomass burning”. Full article

(This article belongs to the Special Issue Advances in Gaseous and Particulate Air Pollutants Measurement)

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14 pages, 5137 KiB

Open AccessArticle

Development of Multi-Item Air Quality Monitoring System Based on Real-Time Data

by Beomseok Park, Sebin Kim, Seoryeong Park, Minji Kim, Tae Yoo Kim and Hanbai Park

Appl. Sci. 2021, 11(20), 9747; https://doi.org/10.3390/app11209747 - 19 Oct 2021

Cited by 6 | Viewed by 3199

Abstract

Many air pollutants are inhaled by human breathing, increasing the prevalence of respiratory disease and even mortality. With the recent COVID-19 issue, the number of air pollutants affecting humans is demands further investigation. However, there are not many adequate air measuring devices that [...] Read more.

Many air pollutants are inhaled by human breathing, increasing the prevalence of respiratory disease and even mortality. With the recent COVID-19 issue, the number of air pollutants affecting humans is demands further investigation. However, there are not many adequate air measuring devices that can cover a variety of air pollutants. In this study, the developed air measurement system is able to measure sixteen air pollutants (PM₁₀, PM_2.5, PM_4.0, PM_1.0, CO₂, CH₄, temperature, humidity, VOCs, O₂, H₂S, NH₃, SO₂, CO, O₃, NO₂) in real time. The developed ‘multi-item air quality monitoring system’ can measure sixteen air pollutants in real time and transmit them to the server and the smartphone application at the same time. It was developed to reduce air pollutant damage to humans by emergency alerts using the smartphone application. The development system is composed of hardware development (measurement device) and software development (smartphone application, server). To verify the reliability of the developed equipment, a comparative test, temperature–humidity accuracy test, and operating temperature test were conducted. In the comparative test, difference ratios of ±5% for PM₁₀, ±6% for PM_2.5, ±4% for O₃, ±5% for NO₂, ±7% for CO, and ±7% for SO₂ were found compared to the professional measuring devices. The temperature and humidity accuracy test result showed high reliability at ±1% and humidity ± 2%. The result of the operating temperature test showed that there was no problem in normal operation, However, further tests including the long-term comparative test and the closed chamber test will be carried out for all sensors. Additional work including a long-term test for more clear reliability of the device and closed chamber accuracy test for all 16-item sensors, data acquisition rate, and data transmit rate are in progress for commercializing the device. Full article

(This article belongs to the Special Issue Advances in Gaseous and Particulate Air Pollutants Measurement)

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10 pages, 3794 KiB

Open AccessArticle

Traceable PM_2.5 and PM₁₀ Calibration of Low-Cost Sensors with Ambient-like Aerosols Generated in the Laboratory

by Stefan Horender, Georgi Tancev, Kevin Auderset and Konstantina Vasilatou

Appl. Sci. 2021, 11(19), 9014; https://doi.org/10.3390/app11199014 - 28 Sep 2021

Cited by 8 | Viewed by 3731

Abstract

This work builds upon previous efforts at calibrating PM (particulate matter) monitors with ambient-like aerosols produced in the laboratory under well-controlled environmental conditions at the facility known as PALMA (Production of Ambient-like Model Aerosols). In this study, the sampling system of PALMA was [...] Read more.

This work builds upon previous efforts at calibrating PM (particulate matter) monitors with ambient-like aerosols produced in the laboratory under well-controlled environmental conditions at the facility known as PALMA (Production of Ambient-like Model Aerosols). In this study, the sampling system of PALMA was equipped with commercial PM_2.5 and PM₁₀ impactors, designed according to the EN 12341:2014 standard, to select different aerosol size fractions for reference gravimetric measurements. Moreover, a metallic frame was mounted around the PM impactor to accommodate up to eight low-cost PM sensors. This sampling unit was placed at the bottom of the 2-meter-long aerosol homogenizer, right above the filter holder for the reference gravimetric measurements. As proof of principle, we used the upgraded PALMA facility to calibrate the new AirVisual Outdoor (IQAir, Goldach, Switzerland) and the SDS011 (InovaFitness, Jinan, China) low-cost PM sensors in a traceable manner against the reference gravimetric method according to the EN 12341 standard. This is the first time that PM_2.5 and PM₁₀ calibrations of low-cost sensors have been successfully carried out with complex ambient-like aerosols consisting of soot, inorganic species, secondary organic matter, and dust particles under controlled temperature and relative humidity. Full article

(This article belongs to the Special Issue Advances in Gaseous and Particulate Air Pollutants Measurement)

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17 pages, 1891 KiB

Open AccessArticle

Influences of Organic Volatile Compounds on the Secondary Organic Carbon of Fine Particulate Matter in the Fruit Tree Area

by Myoungki Song, Minwook Kim, Sea-Ho Oh, Chaehyeong Park, Moonsu Kim, Minsung Kim, Hyunji Lee, Seoyeong Choe and Min-Suk Bae

Appl. Sci. 2021, 11(17), 8193; https://doi.org/10.3390/app11178193 - 3 Sep 2021

Cited by 9 | Viewed by 1827

Abstract

Three combined investigations were conducted to examine the sources of PM_2.5 in agricultural areas. The first was the measurement of PM_2.5 and gaseous compounds in the greenhouse, which is a relatively closed system, while the second was the analysis of pesticide [...] Read more.

Three combined investigations were conducted to examine the sources of PM_2.5 in agricultural areas. The first was the measurement of PM_2.5 and gaseous compounds in the greenhouse, which is a relatively closed system, while the second was the analysis of pesticide components used in agricultural areas. Finally, the physical and chemical properties of PM_2.5 were analyzed in an orchard area and compared with the results of the greenhouse and agricultural chemical analyses. As a result, this research was able to confirm the source of emission and characteristics of PM_2.5 originating from the agricultural area. Volatile organic compounds (VOCs) in agricultural areas are emitted by agricultural chemicals, and the discharged agricultural chemicals are first absorbed into the soil, and then released into the air by evaporation. Finally, the secondary products of PM_2.5 in agricultural areas were estimated to have positive relationships with the VOCs from agricultural chemicals, and NH₃ from fertilizers. The photochemical reactions of VOCs and NH₃ were responsible for the impact on secondary products. Full article

(This article belongs to the Special Issue Advances in Gaseous and Particulate Air Pollutants Measurement)

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11 pages, 1891 KiB

Open AccessArticle

A Fast Method for Estimating the Emission Factors of Air Pollutants from In-Use Vehicles Fleet

by Seung-Bok Lee, Kyung Hwan Kim, Bo-Eun Park and Gwi-Nam Bae

Appl. Sci. 2021, 11(16), 7206; https://doi.org/10.3390/app11167206 - 5 Aug 2021

Cited by 4 | Viewed by 2057

Abstract

The real-world emission factors of gaseous and particulate air pollutants emitted from in-use vehicles, can be rapidly estimated using monitoring data of their concentration profiles from inside roadway tunnels using a mobile laboratory equipped with fast monitoring instruments. The concentrations of CO₂ [...] Read more.

The real-world emission factors of gaseous and particulate air pollutants emitted from in-use vehicles, can be rapidly estimated using monitoring data of their concentration profiles from inside roadway tunnels using a mobile laboratory equipped with fast monitoring instruments. The concentrations of CO₂ and particle-bound polycyclic aromatic hydrocarbons (PM-PAHs) and NO_x, were observed to increase linearly with traveling distance inside two successive roadway tunnels: the Hongjimun Tunnel and the Jeongneung Tunnel on the Naebu Express Way in Seoul, Korea, except for a small region of decrease. In the decreasing regions, within a few hundred meters of the entrance and before the exit, outside background air with low concentrations of air pollutants was thought to have intruded. From the slopes of the linear regression between distance and concentrations, a fleet-averaged (light-, medium-, and heavy-duty vehicles with 54%, 36%, and 10%, respectively) emission factor of CO₂, PM-PAHs, and NO_x at an average speed of ~60 km h⁻¹ could be calculated as 197 ± 38 g km⁻¹, 4.2 ± 0.8 × 10⁻⁴ g km⁻¹, and 0.530 ± 0.230 g km⁻¹, respectively, which are within the ranges of values reported in the literature. For each tunnel, the emission factors of CO₂, PM-PAHs, and NO_x estimated on days with higher-than-normal fractions of heavy-duty vehicles, were higher than those on other days. From these results, the new fast method proposed in this study is considered useful for estimating real-world emission factors of air pollutants by using a mobile laboratory as a complementary tool to traditional tunnel studies. This method can be used to rapidly make emission maps at roadway tunnels in mega-cities like Seoul, Korea, for urban air-quality management. Full article

(This article belongs to the Special Issue Advances in Gaseous and Particulate Air Pollutants Measurement)

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15 pages, 7127 KiB

Open AccessArticle

Polarization Measurements and Evaluation Based on Multidimensional Polarization Indices Applied in Analyzing Atmospheric Particulates

by Riwei Liao, Wei Guo, Nan Zeng, Jun Guo, Yonghong He, Huige Di, Dengxin Hua and Hui Ma

Appl. Sci. 2021, 11(13), 5992; https://doi.org/10.3390/app11135992 - 28 Jun 2021

Cited by 11 | Viewed by 2013

Abstract

Online identification and characterization of suspended aerosols can provide a scientific basis for understanding aerosol transformations, quantitatively evaluating the impacts on air quality, public health, and the source apportionment of different atmospheric particulate matters. In this study, we confirm the validity of our [...] Read more.

Online identification and characterization of suspended aerosols can provide a scientific basis for understanding aerosol transformations, quantitatively evaluating the impacts on air quality, public health, and the source apportionment of different atmospheric particulate matters. In this study, we confirm the validity of our developed high-throughput multi-angle polarized scattering vector detection of aerosols and multidimensional polarization scattering index systems. By observation of the mean values, variance, and Wilk’s Lambda of multidimensional polarization indices for different aerosol types, the polarization index shows unique characterization abilities for aerosol properties, and the optimal combination of polarization indices can always be found for a specific aerosol category with a high resolution and discrimination. Clearly, the multidimensional polarization indices of individual aerosols are more suitable for online and real-time aerosol identification and even help to explain the in situ microphysical characteristics of aerosols or evaluate the dynamic evolution of aerosols. Full article

(This article belongs to the Special Issue Advances in Gaseous and Particulate Air Pollutants Measurement)

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