Role of wastewater treatment in COVID-19 control

The International Water Association (IWA) initiated a Task Force in April 2020 to serve as a leadership team within IWA whose role is to keep abreast and communicate the emerging science, technology, and applications for understanding the impact and the ability to respond to the COVID-19 pandemic and specifically designed for water professionals and industries. Expertise was nominated across the world with the purpose of collectively providing the water sector with knowledge products for the guidance on the control of COVID-19 and other viruses. This review paper developed by a working group of the IWA Task Force focuses on the control of COVID-19. The purpose of this review paper is to provide an understanding of existing knowledge with regards to COVID-19 and provide the necessary guidance of risk mitigation based on currently available knowledge of viruses in wastewater. This review paper considered various scenarios for both the developed world and the developing world and provided recommendations for managing risk. The review paper serves to pool the knowledge with regards to the pandemic and in relation to other viruses. The IWA Task Team envisage that this review paper provides the necessary guidance to the global response to the ongoing pandemic.

A Successful Heat Wave Prevention in Ahmedabad Calls for Segregated Health Record: Highlights from Existing Heat Action Plan

South Asia is one of the hot-spots of extreme heat events and associated health risks. As heat waves continue to get harsher due to climate change, South Asia's exposure to them is probably going to increase. After a heatwave in 2010, Ahmedabad implemented South Asia’s first heat action plan (HAP). The Ahmedabad HAP can serve as a model for other cities across South Asian nations interested in intervention strategies against excessive heat. In recent years, 2020 and onwards, Ahmedabad’s healthcare system faces an extreme COVID-19 crisis which resulted in severe negligence of heat wave-influenced mortality and morbidity cases. Though the city continued to disseminate the necessary information for public heat preparedness from the existing heat action plan, there was no record made separately for COVID-19 and heat stress-related mortality/morbidity by the health department. Thus, due to a lack of heat-related health records, we were unable to track the HAP intervention effect in 2022.

Effects of Dust Event Days on Influenza: Evidence from Arid Environments in Lanzhou

Airborne aerosol is believed to be an important pathway for infectious disease transmissions like COVID-19 and influenza. However, the effects of dust event days on influenza have been rarely explored, particularly in arid environments. This study explores the effects of ambient particulate matter (PM) and dust events on laboratory-confirmed influenza in a semi-arid city. A descriptive analysis of daily laboratory-confirmed influenza (influenza) cases, PM (PM10 and PM2.5), meteorological parameters, and dust events were conducted from 2014 to 2019 in Lanzhou, China. The case-crossover design combined with conditional Poisson regression models was used to estimate the lagging effects of PM and dust events on influenza. In addition, a hierarchical model was used to quantitatively evaluate the interactive effect of PM with ambient temperature and absolute humidity on influenza. We found that PM and dust events had a significant effect on influenza. The effects of PM10 and PM2.5 on influenza became stronger as the cumulative lag days increased. The greatest estimated relative risks (RRs) were 1.018 (1.011,1.024) and 1.061 (1.034,1.087), respectively. Compared with the non-dust days, the effects of dust events with duration ≥ 1 day and with duration ≥ 2 days on influenza were the strongest at lag0 day, with the estimated RRs of 1.245 (95% CI: 1.061–1.463) and 1.483 (95% CI: 1.232–1.784), respectively. Subgroup analysis showed that pre-school children and school-aged children were more sensitive to PM and dust events exposure. Besides, we also found that low humidity and temperature had an interaction with PM to aggravate the risk of influenza. In summary, ambient PM and dust events exposure may increase the risk of influenza, and the risk of influenza increases with the dust events duration. Therefore, more efforts from the government as well as individuals should be strengthened to reduce the effect of PM on influenza, particularly in cold and dry weather.

Size-resolved Compositional Analysis and Source Apportionment of Submicron Aerosol during Lockdown Period Using HR-ToF-AMS

The size-resolved compositional analysis of non-refractory submicron aerosol (NR-PM1) was conducted using the Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) instrument over Pune, India during the COVID-19 lockdown period. The aerosol composition data shows the predominant presence of organics (Org) in the mass fraction followed by sulfate, ammonium, nitrate, and chloride during the pre-lockdown and lockdown periods. The size-resolved analysis showed the unimodal size distribution of organic and inorganic constituents with peaks at 550 nm, implying the dominant presence of mixed and aged aerosol species. The stoichiometric neutralization analysis showed the almost neutralized nature of submicron aerosol with an average aerosol neutralization ratio (ANR) of 0.8. The back trajectories, cluster analysis, and potential source contribution function (PSCF) showed the industrial belt located in the western part of the study location to be the potential source regions of NR-PM1. Positive matrix factorization (PMF) analyses have been applied to investigate the source apportionments of organic aerosols (OA). Four distinct OA factors, i.e., hydrocarbon-like OA (HOA), biomass burning OA (BBOA), low-volatile oxygenated OA (LVOOA), and semi-volatile oxygenated OA (SVOOA) were identified during the study period. Among these factors, HOA contributes nearly a quarter to the OA mass, and OOA accounted for nearly 60% of the total OA mass. The high-resolution positive matrix factorization (HR-PMF) analysis and the elemental ratios of H/C, O/C, and OM/OC showed distinct characteristics during different periods. The density of organic aerosol has been estimated using the elemental ratios and found to be 1.14, 1.28, and 1.35 respectively during the different lockdown periods, similar to 1.30 g cm–3 as mentioned in the literature. This study provides new insights into the chemical composition and source apportionment of the organic fraction of submicron aerosols for the first time over Pune using HR-ToF-AMS and HR-PMF.

Volatile Organic Compound (VOC) Reduction from Face Mask Wastes via a Microwave Plasma Reactor

Since the outbreak of the COVID-19 pandemic, the driven of face masks as personal protective equipment has increased significantly. Thus, disposed face masks from users should be handled properly for preventing the contamination of medical waste and the potential spread of viruses to the environment. This study gives information for dealing with face masks and assessing the volatile organic compounds (VOCs) concentrations via an atmospheric-pressure microwave plasma reactor. Face mask samples were mixed with the flux agents, namely cullet/glass, Al2O3, SiO2 and CaCO3. Samples were compared with control (no addition of flux agents) and the addition of only cullet. Moreover, microwave power, gas flow rate and pyrolysis duration were controlled at 1000 W, 9 standard liter per minute (SLM) and 5 min, respectively. The total concentration of VOC with the absence of flux agents was 448.04 ppm. Furthermore, the fuse of cullet and SiO2-Al2O3-cullet in the mask reduced the concentration of VOCs by 314.77 ppm and 54.7 ppm, respectively. Furthermore, the combination of CaCO3-SiO2-Al2O3-cullet creates the vitrification of material with the presence of crystalline structure, where the compositions of Ca and Si were 13.55% and 19.12%, respectively. Moreover, the final composition of carbon from the flux agents was 17.92 ± 10.08%. This study confirms that the fuse of CaCO3-SiO2-Al2O3-glass/cullet reduced the VOC via plasma technology, which is a promising method to be implemented in order to reduce the concentration of VOC from the face mask waste.

Ozone and Particulate Matter Variations in Southwest Ohio, USA, during the COVID-19 Pandemic in 2020

In this study, ozone and particulate matter variations from four monitoring stations in the Southwest Ohio region were analyzed at different stages of the COVID-19 pandemic in 2020, and compared with those in 2019. These stations include a U.S. EPA NCore site (Taft), an urban-suburban site (Sycamore), an industrial source site (Yankee) and a residential site near the source (Amanda). The air quality time series were broken down to the lockdown period (March 23–May 31) and the re-opening periods from June to December, 2020. Publicly available monitoring data on PM2.5, ozone and PM10 were used for analysis. PM2.5 reductions were non-uniform with strong seasonal variations. PM2.5 reductions were 4.04%, 15.6%, 11.63% at Sycamore, Taft and Yankee sites respectively during the lockdown, but increased 11.23% at Amanda. Reductions at Taft may be related to traffic restrictions while those at Yankee may be due to both reduced industrial production and source control measures. Ozone reductions were 7.94% and 6.50% at Sycamore and Taft sites during the lockdown with Sycamore having higher ozone concentrations pre, during and post lockdown. Ozone formation is NOx-limited in Southwest Ohio region and the variations are uniform. Lower temperatures during the lockdown and fall of 2020 can also be a contributing factor. The Air Quality Index (AQI) of combined ozone and PM2.5 improved during the pandemic year. Consistent with a few other studies, COVID-19 restrictions did not bring uniform air pollutant reductions to the Southwest Ohio region.

Assessment of COVID-19 Impacts on Air Quality in Ulaanbaatar, Mongolia, Based on Terrestrial and Sentinel-5P TROPOMI Data

The study aims to reveal the impact of three sequential strict-lockdowns of COVID-19 measures on the air pollutants including NO2, SO2, PM10, and PM2.5 in Ulaanbaatar, Mongolia during November 2020–February 2021 based on air quality network and satellite data. Based on measurements of automatic air quality sites in Ulaanbaatar, we found a substantial decrease in NO2 (up to 45%), PM10 (72%), and PM2.5 (59%) compared to the same periods in the previous five years. On the other hand, up to a threefold increase in SO2 concentration was seen. Compared to 2015–2020, the number of days exceeding the national air quality standard level of NO2 decreased by 55% during November 2020–February 2021. A similar trend was observed for PM10 and PM2.5 (30% and 14%, respectively). Conversely, days exceeding the national air quality standard level of SO2 increased by 58%. The third strict-lockdown exhibited significant reductions in pollutant concentrations. The percentage exceeding the national standard level for NO2, PM10, and PM2.5 constituted 23%, 50%, and 67% during the lockdown periods while it was 89%, 84%, and 91%, respectively, for the same periods in the previous five years. Even though Sentinel 5P-TROPOMI data do not fully reflect the above findings, they add valuable insights into the spatial pollution pattern during strict-lockdown and non-lockdown periods. The study demonstrates that measures taken during the strict-lockdown periods clearly influenced the values of daily patterns of NO2, PM10, and PM2.5 concentrations. On the contrary, it is important to note that SO2 concentration increased during the last two winter months after 2019.

Impact of COVID-19 Case Numbers on the Emission of Pollutants from a Medical Waste Incineration Plant

This article examines the correlation between the amount of pollutants emitted from medical waste incinerator plant and the number of COVID-19 infections, based on the example of Podlaskie Voivodeship in Poland. This paper deals with the issues of medical waste management during the COVID-19 pandemic. Thermal processing is characterised as a method of medical waste utilisation. The technological sequence of the medical waste incineration installation and the integrated exhaust gas cleaning system are discussed. The results of studies on the emission of pollutants into the atmosphere during combustion are compared with the number of COVID-19 cases in the same voivodeship to investigate how the coronavirus pandemic affects the amount of medical waste generated, thus the amount of pollutants emitted into the atmosphere. The Pearson's linear correlation coefficient and the Student's t-test are used to verify the results. The analysis results show a statistically significant, moderate positive correlation between the amount of covid waste and the number of COVID-19 cases (0.5140). In turn, there is also a statistically significant moderate correlation between the number of COVID-19 cases and emissions of SO2 (r = 0.6256, p = 0.010), NOx (0.5019, p = 0.048), and HCl (0.5130, p = 0.042). This correlation finding highlights additional costs to the environment and public health as the number of COVID-19 cases increase, which can be taken into account for pandemic planning by governments in the future.

Analysis of the Effect and Role of Indoor Environmental Quality in the COVID-19 Transmission

Infectious diseases such as COVID-19 have some risk factors. One of the most important factors is the environment. This research focused on risk factors concerning the house environment. This study aimed to evaluate the parameters of the 'healthy house' environment in controlling the spread of COVID-19. This study used environmental quality, namely ventilation, humidity, brightness, temperature, and personal space area as house environment parameters. The location of the study is Coblong District, Bandung City. The χ2 test of independence was used to show the significance between environmental parameters required for the healthy house and disease transmission. The study found that one house environment parameter (ventilation) are significantly related to indoor transmission rate in recovered patients' houses (p = 0.021). Pearson correlation coefficient r was also investigated for each element of environment factor on the indoor transmission rate. Ventilation was found to be the most significant parameter correlated with indoor transmission (r = –0.522, p = 0.002). Personal Space Area also observed to have a significant correlation with indoor transmission rate (r = 0.459, p = 0.008). Humidity, brightness, and temperature were observed to have no significant correlation with indoor transmission rate (p = 0.309, 0.735, and 0.953, respectively. Linear regression is used to further investigate and predict the indoor transmission rate with significant environmental parameter as predictor. The linear regression model showed that 27.3% of indoor transmission rate variability are caused by its relationship with ventilation, the predictor used in the model.

Microplastics in the Aquatic Environment—The Occurrence, Sources, Ecological Impacts, Fate, and Remediation Challenges

Microplastics are discharged into the environment through human activities and are persistent in the environment. With the prevalent use of plastic-based personal protective equipment in the prevention of the spread of the COVID-19 virus, the concentration of microplastics in the environment is envisaged to increase. Potential ecological and health risks emanate from their potential to adsorb and transport toxic chemicals, and ease of absorption into the cells of living organisms and interfering with physiological processes. This review (1) discusses sources and pathways through which microplastics enter the environment, (2) evaluates the fate and behavior of microplastics, (3) discusses microplastics in African aquatic systems, and (4) identifies research gaps and recommends remediation strategies. Importantly, while there is significant microplastics pollution in the aquatic environment, pollution in terrestrial systems are not widely studied. Besides, there is a dearth of information on microplastics in African aquatic systems. The paper recommends that the governments and non-governmental organizations should fund research to address knowledge gaps, which include: (1) the environmental fate of microplastics, (2) conducting toxicological studies under environmentally relevant conditions, (3) investigating toxicity mechanisms to biota, and developing mitigation measures to safeguard human health, and (4) investigating pollutants transported by microplastics. Moreover, regulatory measures, along with the circular economy strategies, may help reduce microplastic pollution.

An integrated model of aircraft routing and crew rostering problems to develop fair schedule for the crew under COVID-19 condition

This paper focuses on aircraft routing and crew rostering problems simultaneously considering the risk of COVID-19 infection. As airports are among high-risk places in COVID-19 pandemic, the crew prefer to spend less sit time in airports and come back to their home base at the end of each duty day. In this research, an integrated model is developed to assign crew and aircraft to flights in order to achieve a fair schedule for the crew. The objective function is minimisation of the difference between crew sit times. Moreover in this model, a framework including flight hours, number of days and number of take-offs is considered for maintenance requirements. Particle swarm optimisation (PSO) is used as the solution approach. To validate the solution approach, 20 test problems were solved using GAMS and PSO. The results show that PSO improved CPU time significantly (98.279% in average) in turn of 1.902% gap with GAMS in optimum solution.

Unexpected Impact of COVID-19 Lockdown on the Air Quality in the Metro Atlanta, USA Using Ground-based and Satellite Observations

We studied the impact of COVID-19 (coronavirus disease 2019) lockdown on the air quality over the Atlanta area using satellite and ground-based observations, meteorological reanalysis data and traffic information. Unlike other cities, we found the air quality has improved slightly over the Atlanta area during the 2020 COVID-19 lockdown period (March 14–April 30, 2020), compared to the analogous period of 2019 (March 14-April 30, 2019). Ground NO2 concentrations have decreased slightly 10.8% and 8.2% over the near-road (NR) and urban ambient (UA) stations, respectively. Tropospheric NO2 columns have reduced 13%-49% over the Atlanta area from space-borne observations of TROPOspheric Monitoring Instrument (TROPOMI). Ground ozone and PM2.5 have decreased 15.7% an ~5%, respectively. This slight air quality improvement is primarily caused by the reduced human activities, as COVID-19 lockdowns have reduced ~50% human activities, measured by traffic volume. Higher wind speed and precipitations also make the meteorological conditions favorable to this slight air quality improvement. We have not found a significant improvement in Atlanta amid the lockdown when human activities have reduced ~50%. Further studies are needed to understand the impacts of reduced human activities on atmospheric chemistry. We also found TROPOMI and ground measurements have disagreements on NO2 reductions, as collocated TROPOMI observations revealed ~23% and ~21% reductions of tropospheric NO2 columns over NR and UA stations, respectively. Several factors may explain this disagreement: First, tropospheric NO2 columns and ground NO2 concentrations are not necessarily the same, although they are highly correlated in the afternoon;Second, meteorological conditions may have different impacts on TROPMI and ground measurements. Third, TROPOMI may underestimate tropospheric NO2 due to uncertainties from air mass factors. Fourth, the uncertainties of chemiluminescence NO2 measurements used by ground stations. Consequently, studies using space-borne tropospheric NO2 column and ground NO2 measurements should take these factors into account.

The Characteristics of PM2.5 Pollution Episodes during 2016–2019 in Sichuan Basin, China

Many studies have been conducted to explore the characteristics of PM2.5 pollution events in Sichuan Basin, China. However, they focused on either specific regional pollution events from different aspects or the megacities, such as Chengdu and Chongqing. To provide a panorama gram of PM2.5 pollution episodes in the whole basin area, we identified all the PM2.5 pollution events in 17 cities during 2016-2019 and analyzed the characteristics of these events. In total, 1342 episodes were identified and the characteristics of episode numbers, durations and PM2.5 concentrations were analyzed in each city. We found that the characteristics of the temporal and spatial distribution of the episode numbers and durations were similar to the annual average of PM2.5 concentrations, which were higher in the Southern Sichuan and Western Sichuan Plain spatially and occurred most frequently in winter, followed by spring, autumn and summer. Non-monotonical relationships were obtained between the PM2.5 concentrations and pollution durations and there was a duration threshold in each city. For episodes with durations shorter than the threshold, their PM2.5 concentrations increased with duration. The duration thresholds were 6–8 days and 5–7 days in Southern Sichuan and Western Sichuan Plain, respectively. We also found that the air quality deteriorated in 2019 in most cities. Synthetically considering the numbers, durations and concentrations of pollution episodes, more concerns should be taken for the prevention of PM2.5 pollution in Yibin in the Southern Sichuan, Chengdu and Leshan in the Western Sichuan Plain, Neijiang in the Central Hills, and Bazhong, Dazhou, Nanchong in the Northeastern Sichuan. These results could help understanding the characteristics of PM2.5 episodes in Sichuan Basin and providing implications for pollution control strategies in future.

The Impact of Lockdown on eBC Mass Concentration over a Semi-arid Region in Southern India: Ground Observation and Model Simulations

In the present study, we focused on the impact of lockdown on black carbon (eBC) mass concentrations and their associated radiative implications from 01st March to 30th June 2020, over a semi-arid station, i.e., in the district of Anantapur in Southern India. The mean eBC mass concentration was observed before lockdown (01st–24th March 2020) and during the lockdown (25th March–30th June 2020) period and was about 1.74 ± 0.36 and 1.11 ± 0.14 µg m–3, respectively. The sharp decrease (~35%) of eBC mass concentration observed during the lockdown (LD) period as compared with before lockdown (BLD) period, was mainly due to the reduction of anthropogenic activities and meteorology. Furthermore, during the entire LD period, the net composite forcing at the top of the atmosphere (TOA) and at the surface (SUR) varied from –4.52 to –6.19 Wm–2 and –22.91 to –29.35 Wm–2, respectively, whereas the net forcing in the atmosphere (ATM) varied from 17.27 to 23.16 Wm–2. Interestingly, the amount of energy trapped in the atmosphere due to eBC is 11.19 Wm–2 before LD and 8.56 Wm–2 during LD. It is concluded that eBC contributes almost 43–50% to the composite forcing. As a result, the eBC atmospheric heating rate decreased significantly (25%) when compared to before lockdown days to lockdown days.

Assessing the Impact of Traffic Emissions on Fine Particulate Matter and Carbon Monoxide Levels in Hanoi through COVID-19 Social Distancing Periods

Hanoi, Vietnam, is usually ranked as one of the most polluted capital cities in terms of air quality, particularly PM2.5. However, there has not been enough data to determine the main source of this pollution. In this study, we utilized the rare opportunity of the COVID-19 social distancing to assess the contribution of traffic emission to PM2.5 and CO levels when traffic volume was reduced significantly in Hanoi. Hourly PM2.5 and CO concentrations were measured from nine urban and traffic monitoring stations during pre-, soft, hard, and post-social distancing periods. As a result, we observed large reductions in both PM2.5 and CO levels during social distancing periods. PM2.5 concentrations were 14–18% lower during the social distancing than before this period, while CO concentrations had a more considerable drop by 28–41%. It is known that meteorological conditions can have significant effects on the ambient levels of air pollutants. To overcome this challenge, weather normalized concentrations of those pollutants were estimated using the random forest model, a machine learning technique. The normalized weather concentrations showed smaller reductions by 7–10% for PM2.5 and 5–11% for CO, indicating the presence of favorable weather conditions for better air quality during the social distancing period. In further analysis, the apparent improvement of air quality in Hanoi during the social distancing period was in line with reducing traffic emissions while emissions from coal-fired power plants remained relatively stable.

Atmospheric Methane Condition over the South Sumatera Peatland during the COVID-19 Pandemic

Recent anthropogenic activities have degraded peatlands, the largest natural reservoir of soil carbon, thereby reducing their carbon uptake from the atmosphere. As one of the primary sources of methane (CH4) emissions in terrestrial ecosystems, peatlands also contribute to atmospheric greenhouse gases. During the coronavirus disease 2019 (COVID-19) pandemic, Indonesia implemented a lockdown referred to as large-scale social restrictions (LSSR) in areas with high case numbers. To evaluate the effects of anthropogenic activity on peatlands, we investigated the CH4 concentrations in the atmosphere above the tropical peatlands of the Indonesian province South Sumatra before the LSSR (March 2020), during the LSSR (May 2020), and during the corresponding months of the previous year (March and May 2019). Using satellite-retrieved data from NASA, viz., the CH4 concentration and gross primary production (GPP) measured by the Atmospheric Infrared Sounder (AIRS) on board Aqua and Moderate Resolution Imaging Spectroradiometer (MODIS) on board Terra, respectively, we discovered a decrease of approximately 5.5% in the mean CH4 concentration (which averaged 1.73 ppm across the periods prior to lockdown) as well as an increase in the GPP (which ranged from 53.3 to 63.9 g C m–2 day–1 during the lockdown, indicating high atmospheric carbon intake) during the LSSR. Thus, the restrictions during lockdown, which reduced anthropogenic activities, such as land use conversion and biomass burning, and related events, such as peatland and forest fires, significantly influenced the level of atmospheric CH4 above the peatlands in Indonesia.

Improving Filtration Efficacy of Medical Face Masks

We built a simple unipolar positive corona charger and tested it with five different medical face masks. Charging the particles significantly enhanced the filtration efficiencies of all of the masks in terms of the submicron fraction, with an average increase of from 58 to 93% for 0.3 µm particles. Simultaneously, the pressure drop remained practically the same, showing the high potential in using electret media. However, the corona discharge generated ozone, which is an issue that must be addressed. These results contribute to the development of effective solutions against airborne threats.

The Effect of COVID-19 Lockdowns on the Air Pollution of Urban Areas of Central and Southern Chile

We present the effects of the confinement and physical distancing policies applied during the COVID-19 pandemic on the concentrations of PM10, PM2.5, NO, NO2 and O3 in 16 cities in central and southern Chile. The period between March and May in 2020 was compared with the corresponding months during 2017–2019, using surface data and satellite information. The relative percent changes in the concentration of atmospheric pollutants, and the meteorological variables observed between these two periods were used to quantify the effects of the lockdowns on the local air quality of the urban areas studied. The results showed statistically significant changes in 11 of the 16 cities. Significant relative changes between +14% and –33% were observed for PM10 in 9 cities;while statistically significant changes between –6% and –48% were evident for PM2.5 in 10 cities. Significant decreases between –27% and –55%, were observed in 4 cities in which NO2 data were available;while significant increases in O3, between 18% and 43%, were found in 4 of the 5 cities with available data. The local meteorological variables did not show significant changes between both periods. In all the cities studied, one of the main PM sources is wood burning for residential heating. Although the quarantine imposed during the health emergency could have induced an increase in residential emissions, these were compensated with the reductions in vehicular and/or industrial emissions. Therefore, these results should be carefully interpreted and should inspire new research considering the social, cultural, and economic factors that could alter the common emission patterns and air quality of urban centers.