What can we learn about urban air quality with regard to the first outbreak of the COVID-19 pandemic? A case study from Central Europe

Abstract. Motor vehicle road traffic in central Budapest was reduced by approximately 50 % of its ordinary level for several weeks as a consequence of various limitation measures introduced to mitigate the first outbreak of the COVID-19 pandemic in 2020. The situation was utilised to assess the real potentials of urban traffic on air quality. Concentrations of NO, NO2, CO, O3, SO2 and particulate matter (PM) mass, which are ordinarily monitored in cities for air quality considerations, aerosol particle number size distributions, which are not rarely measured continuously on longer runs for research purposes, and meteorological properties usually available were collected and jointly evaluated in different pandemic phases. The largest changes occurred over the severest limitations (partial lockdown in the Restriction phase from 28 March to 17 May 2020). Concentrations of NO, NO2, CO, total particle number (N6–1000) and particles with a diameter < 100 nm declined by 68 %, 46 %, 27 %, 24 % and 28 %, respectively, in 2020 with respect to the average reference year comprising 2017–2019. Their quantification was based on both relative difference and standardised anomaly. The change rates expressed as relative concentration difference due to relative reduction in traffic intensity for NO, NO2, N6–1000 and CO were 0.63, 0.57, 0.40 and 0.22 (%/%), respectively. Of the pollutants which reacted in a sensitive manner to the change in vehicle circulation, it is the NO2 that shows the most frequent exceedance of the health limits. Intentional tranquillising of the vehicle flow has considerable potential for improving the air quality. At the same time, the concentration levels of PM10 mass, which is the most critical pollutant in many European cities including Budapest, did not seem to be largely affected by vehicles. Concentrations of O3 concurrently showed an increasing tendency with lower traffic, which was explained by its complex reaction mechanism. Modelling calculations indicated that spatial gradients of NO and NO2 within the city became further enhanced by reduced vehicle flow.

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Fractal Dimension of Floc Growth in Micro-Coagulation Stage I: Using to Forecast Water Quality of Settled Water

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.4831 ◽

2011 ◽

Vol 243-249 ◽

pp. 4831-4834 ◽

Cited By ~ 1

Author(s):

Jun Nan ◽

Hao Yu Li ◽

Wei Peng He

Keyword(s):

Water Quality ◽

Particle Size ◽

Fractal Dimension ◽

Particle Number ◽

Coagulation Process ◽

Total Particle Number ◽

Total Particle ◽

On Line ◽

Line Detector

The coagulation experiments, with Kaolin as objects, aluminum chloride (PAC) as coagulant, were accomplished under different conditions. In the experiment, the particle size distribution and turbidity in water were detected by on-line detector. Result showed that all floc changed in speed in the first 5 min of the coagulation process and the fractal dimension of floc growth in the first 4 min of coagulation process had best linear relation (R2 was biggest and more than 0.92 )with turbidity, total particle number and the number of particle size <5µm of settled water. The fractal dimension had a direct ratio relation with water quality of settled water and could be used as a factor to forecast water quality of settled water.

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A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-6-10551-2013 ◽

2013 ◽

Vol 6 (6) ◽

pp. 10551-10570

Author(s):

A. Schladitz ◽

M. Merkel ◽

S. Bastian ◽

W. Birmili ◽

K. Weinhold ◽

...

Keyword(s):

Particle Size ◽

Air Quality ◽

Particle Number ◽

Zero Point ◽

Number Concentration ◽

Quality Monitoring ◽

Particle Number Concentration ◽

Air Quality Monitoring ◽

Total Particle Number ◽

Total Particle

Abstract. An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The aim of the new feature is to conduct unattended quality control experiments under field conditions at remote air quality monitoring or research stations. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter removing the diffusive particles approximately smaller than 25 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. The other feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. An exemplary one-year data set is presented for the measurement site Annaberg-Buchholz as part of the Saxon air quality monitoring network. The total particle number concentration derived from the mobility particle size spectrometer overestimates the particle number concentration by only 2% (grand average offset). Furthermore, tolerance criteria are presented to judge the performance of the mobility particle size spectrometer with respect to the particle number concentration. An upgrade of a mobility particle size spectrometer with an automated function control enhances the quality of long-term particle number size distribution measurements. Quality assured measurements are a precondition for intercomparison studies of different sites. Comparable measurements will improve cohort health and also climate-relevant research studies.

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Contribution of traffic-originated nanoparticle emissions to regional and local aerosol levels

10.5194/acp-2021-466 ◽

2021 ◽

Author(s):

Miska Olin ◽

David Patoulias ◽

Heino Kuuluvainen ◽

Jarkko V. Niemi ◽

Topi Rönkkö ◽

...

Keyword(s):

Particle Size ◽

Chemical Composition ◽

Particle Size Distribution ◽

Size Distribution ◽

Urban Areas ◽

Particle Number ◽

Road Traffic ◽

Regional Scale ◽

Total Particle Number ◽

Total Particle

Abstract. Sub-50 nm particles originating from traffic emissions pose risks to human health due to their high lung deposition efficiency and potentially harmful chemical composition. We present a modelling study using an updated EUCAARI number emission inventory, incorporating a more realistic, empirically justified particle size distribution (PSD) for sub-50 nm particles from road traffic. We present experimental PSDs and CO2 concentrations, measured in a highly trafficked street canyon in Helsinki, Finland, as an emission factor particle size distribution (EFPSD), which was then used in updating the EUCAARI inventory. We applied the updated inventory in a simulation using the regional chemical transport model PMCAMx-UF over Europe for May 2008 to test the effect of updated emissions in regional and local scales and in contrast to atmospheric new particle formation (NPF). Updating the inventory increased simulated average total particle number concentrations by only 1 %, although the total particle number emissions were increased to a 3-fold level. The concentrations increased up to 11 % when only 1.3–3 nm-sized particles (nanocluster aerosol, NCA) were considered. These values indicate that the effect of updating overall is insignificant in a regional scale during this photochemically active period, during which the fraction of the total particle number originating through atmospheric NPF processes was 91 %. These simulations give a lower limit for the contribution of traffic to the aerosol levels. Nevertheless, the situation is different when examining the effect of the update spatially or temporally, or when focusing to the chemical composition or the origin of the particles. For example, daily average NCA concentrations increased by a factor of several hundreds or thousands in some locations on certain days. Overall, the most significant effects–reaching several orders of magnitude–from updating the inventory are observed when examining specific particle sizes (especially 7–20 nm), particle components, and specific urban areas. While the model still has a tendency to predict more sub-50 nm particles compared to the observations, the most notable underestimations in the concentrations of sub-10 nm particles are, after updating, overcome and the simulated distributions now agree better with the data observed at locations having high traffic densities. The findings of this study highlight the need to consider emissions, PSDs, and composition of sub-50 nm particles from road traffic in studies focusing on urban air quality. Updating this emission source brings the simulated aerosol levels particularly in urban locations closer to observations, which highlights its importance for calculations of human exposure to nanoparticles.

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Impact of the Coronavirus Pandemic Lockdown on Atmospheric Nanoparticle Concentrations in Two Sites of Southern Italy

Atmosphere ◽

10.3390/atmos12030352 ◽

2021 ◽

Vol 12 (3) ◽

pp. 352

Author(s):

Adelaide Dinoi ◽

Daniel Gulli ◽

Ivano Ammoscato ◽

Claudia R. Calidonna ◽

Daniele Contini

Keyword(s):

Particle Number ◽

Southern Italy ◽

Time Intervals ◽

Atmospheric Particle ◽

Total Particle Number ◽

Total Particle ◽

Consequent Reduction ◽

Containment Measures ◽

Coronavirus Infection ◽

The Impact

During the new coronavirus infection outbreak, the application of strict containment measures entailed a decrease in most human activities, with the consequent reduction of anthropogenic emissions into the atmosphere. In this study, the impact of lockdown on atmospheric particle number concentrations and size distributions is investigated in two different sites of Southern Italy: Lecce and Lamezia Terme, regional stations of the GAW/ACTRIS networks. The effects of restrictions are quantified by comparing submicron particle concentrations, in the size range from 10 nm to 800 nm, measured during the lockdown period and in the same period of previous years, from 2015 to 2019, considering three time intervals: prelockdown, lockdown and postlockdown. Different percentage reductions in total particle number concentrations are observed, −19% and −23% in Lecce and −7% and −4% in Lamezia Terme during lockdown and postlockdown, respectively, with several variations in each subclass of particles. From the comparison, no significant variations of meteorological factors are observed except a reduction of rainfall in 2020, which might explain the higher levels of particle concentrations measured during prelockdown at both stations. In general, the results demonstrate an improvement of air quality, more conspicuous in Lecce than in Lamezia Terme, during the lockdown, with a differed reduction in the concentration of submicronic particles that depends on the different types of sources, their distance from observational sites and local meteorology.

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Vertical marine snow distribution in the stratified, hypersaline, and anoxic Orca Basin (Gulf of Mexico)

Elem Sci Anth ◽

10.1525/elementa.348 ◽

2019 ◽

Vol 7 ◽

Cited By ~ 3

Author(s):

Arne Diercks ◽

Kai Ziervogel ◽

Ryan Sibert ◽

Samantha B. Joye ◽

Vernon Asper ◽

...

Keyword(s):

Organic Carbon ◽

Gulf Of Mexico ◽

Particle Number ◽

Sea Surface ◽

Marine Snow ◽

Particle Volume ◽

Total Particle Number ◽

Total Particle ◽

Snow Distribution ◽

Orca Basin

We present a complete description of the depth distribution of marine snow in Orca Basin (Gulf of Mexico), from sea surface through the pycnocline to within 10 m of the seafloor. Orca Basin is an intriguing location for studying marine snow because of its unique geological and hydrographic setting: the deepest ~200 m of the basin are filled with anoxic hypersaline brine. A typical deep ocean profile of marine snow distribution was observed from the sea surface to the pycnocline, namely a surface maximum in total particle number and midwater minimum. However, instead of a nepheloid (particle-rich) layer positioned near the seabed, the nepheloid layer in the Orca Basin was positioned atop the brine. Within the brine, the total particle volume increased by a factor of 2–3 while the total particle number decreased, indicating accumulation and aggregation of material in the brine. From these observations we infer increased residence time and retention of material within the brine, which agrees well with laboratory results showing a 2.2–3.5-fold reduction in settling speed of laboratory-generated marine snow below the seawater-brine interface. Similarly, dissolved organic carbon concentration in the brine correlated positively with measured colored dissolved organic matter (r2 = 0.92, n = 15), with both variables following total particle volume inversely through the pycnocline. These data indicate the release of dissolved organic carbon concomitant with loss in total particle volume and increase in particle numbers at the brine-seawater interface, highlighting the importance of the Orca Basin as a carbon sink.

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Urban aerosol size distributions over the Mediterranean city of Barcelona, NE Spain

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-16457-2012 ◽

2012 ◽

Vol 12 (7) ◽

pp. 16457-16492 ◽

Cited By ~ 3

Author(s):

M. Dall'Osto ◽

D.C.S. Beddows ◽

J. Pey ◽

S. Rodriguez ◽

A. Alastuey ◽

...

Keyword(s):

Particle Number ◽

Number Concentration ◽

Aerosol Size Distribution ◽

Time Variability ◽

Small Contribution ◽

Particle Number Concentration ◽

Size Distributions ◽

Total Particle Number ◽

Total Particle ◽

One Year

Abstract. Differential mobility particle sizer (DMPS) aerosol concentrations (N13–800) were collected over a one-year-period (2004) at an urban background site in Barcelona, North-Eastern Spain. Quantitative contributions to particle number concentrations of the nucleation (33–38%), Aitken (39–49%) and accumulation mode (18–22%) were estimated. We examined the source and time variability of atmospheric aerosol particles by using both K-means clustering and Positive Matrix Factorization (PMF) analysis. Performing clustering analysis on hourly size distributions, nine K-means DMPS clusters were identified and, by directional association, diurnal variation and relationship to meteorological and pollution variables, four typical aerosol size distribution scenarios were identified: traffic (69% of the time), dilution (15% of the time), summer background conditions (4% of the time) and regional pollution (12% of the time). According to the results of PMF, vehicle exhausts are estimated to contribute at least to 62–66% of the total particle number concentration, with a slightly higher proportion distributed towards the nucleation mode (34%) relative to the Aitken mode (28–32%). Photochemically induced nucleation particles make only a small contribution to the total particle number concentration (2–3% of the total), although only particles larger than 13 nm were considered in this study. Overall the combination of the two statistical methods is successful at separating components and quantifying relative contributions to the particle number population.

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Long-Term Characterization of Submicron Atmospheric Particles in an Urban Background Site in Southern Italy

Atmosphere ◽

10.3390/atmos11040334 ◽

2020 ◽

Vol 11 (4) ◽

pp. 334 ◽

Cited By ~ 3

Author(s):

Adelaide Dinoi ◽

Marianna Conte ◽

Fabio M. Grasso ◽

Daniele Contini

Keyword(s):

Particle Number ◽

Meteorological Parameters ◽

Particle Diameter ◽

Number Concentration ◽

Total Particle Number ◽

Total Particle ◽

Late Evening ◽

20 Nm

Continuous measurements of particle number size distributions in the size range from 10 nm to 800 nm were performed from 2015 to 2019 at the ECO Environmental-Climate Observatory of Lecce (Global Atmosphere Watch Programme/Aerosol, Clouds and Trace Gases Research Infrastructure (GAW/ACTRIS) regional station). The main objectives of this work were to investigate the daily, weekly and seasonal trends of particle number concentrations and their dependence on meteorological parameters gathering information on potential sources. The highest total number concentrations were observed during autumn-winter with average values nearly twice as high as in summer. More than 52% of total particle number concentration consisted of Aitken mode (20 nm < particle diameter (Dp) < 100 nm) particles followed by accumulation (100 nm < Dp < 800 nm) and nucleation (10 nm < Dp < 20 nm) modes representing, respectively, 27% and 21% of particles. The total number concentration was usually significantly higher during workdays than during weekends/holidays in all years, showing a trend likely correlated with local traffic activities. The number concentration of each particle mode showed a characteristic daily variation that was different in cold and warm seasons. The highest concentrations of the Aitken and accumulation particle mode were observed in the morning and the late evening, during typical rush hour traffic times, highlighting that the two-particle size ranges are related, although there was significant variation in the number concentrations. The peak in the number concentrations of the nucleation mode observed in the midday of spring and summer can be attributed to the intensive formation of new particles from gaseous precursors. Based on Pearson coefficients between particle number concentrations and meteorological parameters, temperature, and wind speed had significant negative relationships with the Aitken and accumulation particle number concentrations, whereas relative humidity was positively correlated. No significant correlations were found for the nucleation particle number concentrations.

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Classification of aerosol population type and cloud condensation nuclei properties in a coastal California littoral environment using an unsupervised cluster model

10.5194/acp-2018-1297 ◽

2019 ◽

Author(s):

Samuel A. Atwood ◽

Sonia M. Kreidenweis ◽

Paul J. DeMott ◽

Markus D. Petters ◽

Gavin C. Cornwell ◽

...

Keyword(s):

Cluster Model ◽

Particle Number ◽

Cloud Condensation Nuclei ◽

Sea Breeze ◽

Northern Coast ◽

Size Distributions ◽

Condensation Nuclei ◽

Entire Study ◽

Total Particle Number ◽

Total Particle

Abstract. Aerosol particle and cloud condensation nuclei (CCN) measurements from a littoral location on the northern coast of California at Bodega Bay Marine Laboratory (BML) are presented for approximately six weeks of observations during the CalWater-2015 field campaign. A combination of aerosol microphysical and meteorological parameters was used to classify variability in the properties of the BML surface aerosol using a K-means cluster model. Eight aerosol population types were identified that were associated with a range of impacts from both marine and terrestrial sources. Average measured total particle number concentrations, size distributions, hygroscopicities, and activated fraction spectra between 0.08 % and 1.1 % supersaturation are given for each of the identified aerosol population types, along with meteorological observations and transport pathways during time periods associated with each type. Five terrestrially influenced aerosol population types represented different degrees of aging of the continental outflow from the coast and interior of California and their appearance at the BML site was often linked to changes in wind direction and transport pathway. In particular, distinct aerosol populations, associated with diurnal variations in source region induced by land/sea-breeze shifts, were classified by the clustering technique. A terrestrial type representing fresh emissions, and/or a recent new particle formation event, occurred in approximately 10 % of the observations. Over the entire study period, three marine influenced population types were identified that typically occurred when the regular diurnal land/sea-breeze cycle collapsed and BML was continuously ventilated by air masses from marine regions for multiple days. These marine types differed from each other primarily in the degree of cloud processing evident in the size distributions, and in the presence of an additional large-particle mode for the type associated with the highest wind speeds. One of the marine types was associated with a multi-day period during which an atmospheric river made landfall at BML. The generally higher total particle number concentrations but lower activated fractions of four of the terrestrial types yielded similar CCN number concentrations to two of the marine types for supersaturations below about 0.4 %. Despite quite different activated fraction spectra, the two remaining marine and terrestrial types had CCN spectral number concentrations very similar to each other, due in part to higher number concentrations associated with the terrestrial type.

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Introducing Eco Friendly Urban Traffic Control Room

International Journal of Green Computing ◽

10.4018/ijgc.2017070105 ◽

2017 ◽

Vol 8 (2) ◽

pp. 77-97

Author(s):

Somasree Bhadra ◽

Anirban Kundu ◽

Sunirmal Khatua

Keyword(s):

Traffic Control ◽

Service Sector ◽

Road Traffic ◽

Urban Traffic ◽

City Management ◽

Control Room ◽

Computing Environment ◽

Efficient Manner ◽

Urban Traffic Control

In this article, new services in Green Computing environment is introduced. Energy and power is saved in an efficient manner using proposed services. These services are still undefined to the researchers in most of the cases. A typical framework of hierarchical structure for typical software managed central urban traffic control room is considered as case study. Each type of services is shown with an example which is interrelated with central traffic control room scenario. The authors' aim is to produce an energy efficient and power savings method in computing environment. Urban Traffic Control Room is considered as a case study. This is because in today's world urban traffic management is one of the most burning issues of any smart city management. Use of complex yet efficient software in the urban traffic control room may aid in proper management of road traffic. Keeping in mind growing environmental concerns, efficient green system architecture needs to be in place to ensure high performance, reliability and security of such an important public service sector.

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