LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 10 of total 11

Search options

  1. Article ; Online: The impact of low emission zones on personal exposure to ultrafine particles in the commuter environment.

    Patel, Hamesh / Talbot, Nick / Dirks, Kim / Salmond, Jennifer

    The Science of the total environment

    2023  Volume 874, Page(s) 162540

    Abstract: Auckland is a city with limited industrial activity, road traffic being the dominant source of air pollution. Thus, the time periods when social contact and movement in Auckland were severely curtailed due to COVID-19 restrictions presented a unique ... ...

    Abstract Auckland is a city with limited industrial activity, road traffic being the dominant source of air pollution. Thus, the time periods when social contact and movement in Auckland were severely curtailed due to COVID-19 restrictions presented a unique opportunity to observe impacts on pedestrian exposure to air pollution under a range of different traffic flow scenarios, providing insights into the impacts of potential future traffic calming measures. Pedestrian exposure to ultrafine particles (UFPs), was measured using personal monitoring along a customised route through Central Auckland during different COVID-19-affected traffic flow conditions. Results showed that reduced traffic flows led to statistically significant reductions in average exposure to UFP under all traffic reduction scenarios (TRS). However, the size of the reduction was variable in both time and place. Under the most stringent TRS (traffic reduction of 82 %), median ultrafine particle (UFP) concentrations reduced by 73 %. Under the less stringent scenario, the extent of reduction varied in time and space; a traffic reduction of 62 % resulted in a 23 % reduction in median UFP concentrations in 2020 but in 2021 similar traffic reductions led to a decrease in median UFP concentrations of 71 %. Under all scenarios, the magnitude of the impact of traffic reductions on UFP exposure varied along the route, with areas dominated by emissions from construction and ferry/port activities showing little correlation between traffic flow and exposure. Shared traffic spaces, previously pedestrianised, also recorded consistently high concentrations with little variability observed. This study provided a unique opportunity to assess the potential benefits and risks of such zones and to help decision-makers evaluate future traffic management interventions (such as low emissions zones). The results suggest that controlled traffic flow interventions can result in a significant reduction in pedestrian exposure to UFPs, but that the magnitude of reductions is sensitive to local-scale variations in meteorology, urban land use and traffic flow patterns.
    MeSH term(s) Humans ; Particulate Matter/analysis ; Air Pollutants/analysis ; Vehicle Emissions/analysis ; COVID-19 ; Environmental Monitoring/methods ; Air Pollution/analysis ; Particle Size
    Chemical Substances Particulate Matter ; Air Pollutants ; Vehicle Emissions
    Language English
    Publishing date 2023-03-03
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2023.162540
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  2. Article ; Online: Reanalysis of historic elemental speciation filters to investigate the presence of fibrous mineral particles using microscopy techniques

    Nick Talbot / Kim N. Dirks / Wendy Fan / Hamesh Patel / Seosamh B. Costello / Martin Brook / Perry Davy

    Frontiers in Chemistry, Vol

    2022  Volume 10

    Abstract: A case is presented for the value of archiving air quality filters to allow for retrospective analysis of emerging contaminants, that is filter constituents not considered to be harmful (and thus not identified or quantified specifically) at the time of ... ...

    Abstract A case is presented for the value of archiving air quality filters to allow for retrospective analysis of emerging contaminants, that is filter constituents not considered to be harmful (and thus not identified or quantified specifically) at the time of collection but subsequently considered to be of interest. As an example, filters from a 20-year historical archive consisting of 16,000 filters from three sites across Auckland are re-examined for the presence of elongated mineral fibres known to be present in rock across the city. Originally collected for the purpose of the source apportionment of particulate matter, 10 filters from each of the three sites were chosen for reanalysis based on their high silica and aluminium content, and thus considered more likely to contain fibre-like particles (FLP). These filters were analysed using various microscopic methods, including phase contrast microscopy (PCM), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). The results show that although the commonly used fibrous polytetrafluoroethylene (PTFE) material of the filters may hamper the visual identification of any fibre-like particles under a certain length, their key components are able to be identified using a combination of PCM and SEM when they are of a suitable dimension and have settled in a certain orientation on the filter. In this case, the use of EDS confirmed the silicon content of the fibres and also revealed elemental spectra. Although the exact identification of the mineral fibre is uncertain, the EDS scan is consistent with hazardous zeolites such as erionite, known to be present in the rock found in Auckland. This study highlights the value in maintaining filter archives for the purpose of investigating the historical evolution of emerging atmospheric pollutants.
    Keywords erionite ; scanning electron microscopy (SEM) ; reanalysis ; PTFE filters ; energy dispersive analysis (EDS) ; Chemistry ; QD1-999
    Subject code 621
    Language English
    Publishing date 2022-11-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

  3. Article: Reanalysis of historic elemental speciation filters to investigate the presence of fibrous mineral particles using microscopy techniques.

    Talbot, Nick / Dirks, Kim N / Fan, Wendy / Patel, Hamesh / Costello, Seosamh B / Brook, Martin / Davy, Perry

    Frontiers in chemistry

    2022  Volume 10, Page(s) 1032624

    Abstract: A case is presented for the value of archiving air quality filters to allow for retrospective analysis of emerging contaminants, that is filter constituents not considered to be harmful (and thus not identified or quantified specifically) at the time of ... ...

    Abstract A case is presented for the value of archiving air quality filters to allow for retrospective analysis of emerging contaminants, that is filter constituents not considered to be harmful (and thus not identified or quantified specifically) at the time of collection but subsequently considered to be of interest. As an example, filters from a 20-year historical archive consisting of 16,000 filters from three sites across Auckland are re-examined for the presence of elongated mineral fibres known to be present in rock across the city. Originally collected for the purpose of the source apportionment of particulate matter, 10 filters from each of the three sites were chosen for reanalysis based on their high silica and aluminium content, and thus considered more likely to contain fibre-like particles (FLP). These filters were analysed using various microscopic methods, including phase contrast microscopy (PCM), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). The results show that although the commonly used fibrous polytetrafluoroethylene (PTFE) material of the filters may hamper the visual identification of any fibre-like particles under a certain length, their key components are able to be identified using a combination of PCM and SEM when they are of a suitable dimension and have settled in a certain orientation on the filter. In this case, the use of EDS confirmed the silicon content of the fibres and also revealed elemental spectra. Although the exact identification of the mineral fibre is uncertain, the EDS scan is consistent with hazardous zeolites such as erionite, known to be present in the rock found in Auckland. This study highlights the value in maintaining filter archives for the purpose of investigating the historical evolution of emerging atmospheric pollutants.
    Language English
    Publishing date 2022-11-03
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2711776-5
    ISSN 2296-2646
    ISSN 2296-2646
    DOI 10.3389/fchem.2022.1032624
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  4. Article ; Online: Implications for air quality management of changes in air quality during lockdown in Auckland (New Zealand) in response to the 2020 SARS-CoV-2 epidemic.

    Patel, Hamesh / Talbot, Nick / Salmond, Jennifer / Dirks, Kim / Xie, Shanju / Davy, Perry

    The Science of the total environment

    2020  Volume 746, Page(s) 141129

    Abstract: The current changes in vehicle movement due to 'lockdown' conditions (imposed in cities worldwide in response to the COVID-19 epidemic) provide opportunities to quantify the local impact of 'controlled interventions' on air quality and establish baseline ...

    Abstract The current changes in vehicle movement due to 'lockdown' conditions (imposed in cities worldwide in response to the COVID-19 epidemic) provide opportunities to quantify the local impact of 'controlled interventions' on air quality and establish baseline pollution concentrations in cities. Here, we present a case study from Auckland, New Zealand, an isolated Southern Hemisphere city, which is largely unaffected by long-range pollution transport or industrial sources of air pollution. In this city, traffic flows reduced by 60-80% as a result of a government-led initiative to contain the virus by limiting all transport to only essential services. In this paper, ambient pollutant concentrations of NO
    MeSH term(s) Air Pollutants/analysis ; Air Pollution/analysis ; Air Pollution/prevention & control ; Betacoronavirus ; COVID-19 ; Cities ; Coronavirus Infections ; Environmental Monitoring ; Humans ; New Zealand/epidemiology ; Pandemics ; Particulate Matter/analysis ; Pneumonia, Viral ; SARS-CoV-2 ; Severe Acute Respiratory Syndrome
    Chemical Substances Air Pollutants ; Particulate Matter
    Keywords covid19
    Language English
    Publishing date 2020-07-27
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2020.141129
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  5. Article ; Online: Implications for air quality management of changes in air quality during lockdown in Auckland (New Zealand) in response to the 2020 SARS-CoV-2 epidemic

    Patel, Hamesh / Talbot, Nick / Salmond, Jennifer / Dirks, Kim / Xie, Shanju / Davy, Perry

    Science of The Total Environment

    2020  Volume 746, Page(s) 141129

    Keywords Environmental Engineering ; Waste Management and Disposal ; Pollution ; Environmental Chemistry ; covid19
    Language English
    Publisher Elsevier BV
    Publishing country us
    Document type Article ; Online
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2020.141129
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

  6. Article: Low-cost sensor networks and land-use regression: Interpolating nitrogen dioxide concentration at high temporal and spatial resolution in Southern California

    Weissert, Lena / Alberti, Kyle / Feenstra, Brandon / Henshaw, Geoff S / Miles, Elaine / Miskell, Georgia / Papapostolou, Vasileios / Patel, Hamesh / Polidori, Andrea / Salmond, Jennifer A / Williams, David E

    Elsevier Ltd Atmospheric environment. 2020 Feb. 15, v. 223

    2020  

    Abstract: The development of low-cost sensors and novel calibration algorithms offer new opportunities to supplement existing regulatory networks to measure air pollutants at a high spatial resolution and at hourly and sub-hourly timescales. We use a random forest ...

    Abstract The development of low-cost sensors and novel calibration algorithms offer new opportunities to supplement existing regulatory networks to measure air pollutants at a high spatial resolution and at hourly and sub-hourly timescales. We use a random forest model on data from a network of low-cost sensors to describe the effect of land use features on local-scale air quality, extend this model to describe the hourly-scale variation of air quality at high spatial resolution, and show that deviations from the model can be used to identify particular conditions and locations where air quality differs from the expected land-use effect. The conditions and locations under which deviations were detected conform to expectations based on general experience.
    Keywords air pollutants ; air pollution ; air quality ; algorithms ; land use ; models ; nitrogen dioxide ; California
    Language English
    Dates of publication 2020-0215
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 216368-8
    ISSN 0004-6981 ; 1352-2310
    ISSN 0004-6981 ; 1352-2310
    DOI 10.1016/j.atmosenv.2020.117287
    Database NAL-Catalogue (AGRICOLA)

    More links

    Kategorien

  7. Article: Implications for air quality management of changes in air quality during lockdown in Auckland (New Zealand) in response to the 2020 SARS-CoV-2 epidemic

    Patel, Hamesh / Talbot, Nick / Salmond, Jennifer / Dirks, Kim / Xie, Shanju / Davy, Perry

    Sci Total Environ

    Abstract: The current changes in vehicle movement due to 'lockdown' conditions (imposed in cities worldwide in response to the COVID-19 epidemic) provide opportunities to quantify the local impact of 'controlled interventions' on air quality and establish baseline ...

    Abstract The current changes in vehicle movement due to 'lockdown' conditions (imposed in cities worldwide in response to the COVID-19 epidemic) provide opportunities to quantify the local impact of 'controlled interventions' on air quality and establish baseline pollution concentrations in cities. Here, we present a case study from Auckland, New Zealand, an isolated Southern Hemisphere city, which is largely unaffected by long-range pollution transport or industrial sources of air pollution. In this city, traffic flows reduced by 60-80% as a result of a government-led initiative to contain the virus by limiting all transport to only essential services. In this paper, ambient pollutant concentrations of NO2, O3, BC, PM2.5, and PM10 are compared between the lockdown period and comparable periods in the historical air pollution record, while taking into account changes in the local meteorology. We show that this 'natural experiment' in source emission reductions had significant but non-linear impacts on air quality. While emission inventories and receptor modelling approaches confirm the dominance of traffic sources for NOx (86%), and BC (72%) across the city, observations suggest a consequent reduction in NO2 of only 34-57% and a reduction in BC of 55-75%. The observed reductions in PM2.5 (still likely to be dominated by traffic emissions), and PM10 (dominated by sea salt, traffic emissions to a lesser extent, and affected by seasonality) were found to be significantly less (8-17% for PM2.5 and 7-20% for PM10). The impact of this unplanned controlled intervention shows the importance of establishing accurate, local-scale emission inventories, and the potential of the local atmospheric chemistry and meteorology in limiting their accuracy.
    Keywords covid19
    Publisher WHO
    Document type Article
    Note WHO #Covidence: #714991
    Database COVID19

    Kategorien

  8. Article: Hierarchical network design for nitrogen dioxide measurement in urban environments

    Weissert, Lena / Miles, Elaine / Miskell, Georgia / Alberti, Kyle / Feenstra, Brandon / Henshaw, Geoff S / Papapostolou, Vasileios / Patel, Hamesh / Polidori, Andrea / Salmond, Jennifer A / Williams, David E

    Elsevier Ltd Atmospheric environment. 2020 May 01, v. 228

    2020  

    Abstract: We present a management and data correction framework for low-cost electrochemical sensors for nitrogen dioxide (NO2) deployed within a hierarchical network of low-cost and regulatory-grade instruments. The framework is founded on the idea that it is ... ...

    Abstract We present a management and data correction framework for low-cost electrochemical sensors for nitrogen dioxide (NO2) deployed within a hierarchical network of low-cost and regulatory-grade instruments. The framework is founded on the idea that it is possible in a suitably configured network to identify a source of reliable ‘proxy’ data for each sensor site that has a similar probability distribution of measurement values over a suitable time period, and that sensor data can be checked and corrected by comparison of the sensor data distribution with that of the proxy. The framework is rule-based and easily modified. We use the reference network to choose proxies and check proxy reliability. We demonstrate the application of this methodology to low-cost instruments that use an electrochemical NO2 sensor together with a semiconducting oxide-based sensor for ozone (O3). The three NO2 sensor response parameters (offset, O3 response slope, and NO2 response slope) which are known to vary significantly as a consequence of ambient humidity and temperature variations, we show can be estimated by minimising statistical measures of divergence between sensor-estimated and proxy NO2 distributions over a 3-day window. We show how the parameter variations and statistical divergence measures with respect to the proxy can be used to indicate error conditions. The major error is due to a diurnally-varying, spatially-correlated offset term that is large for extremes of temperature, which we show can be estimated through its spatial correlation, using sensors co-located at reference sites. With these procedures, we demonstrate measurement at nine different locations across two regions of Southern California over seven months with average root mean square error ±7.2 ppb (range over locations 4–11 ppb) without calibration other than the remote proxy comparison. We apply the procedures to a network of 56 sensors distributed across the Inland Empire and Los Angeles County regions. The results show large variations in NO2 concentration taking place on short time- and distance scales across the region. These spatiotemporal NO2 variations were not captured by the more sparsely distributed regulatory network of air monitoring stations demonstrating the need for reliable data from dense networks of monitors to supplement the existing regulatory networks.
    Keywords air ; atmospheric chemistry ; calibration ; electrochemistry ; humidity ; monitoring ; nitrogen dioxide ; ozone ; probability distribution ; semiconductors ; sensors (equipment) ; temperature ; urban areas ; California
    Language English
    Dates of publication 2020-0501
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 216368-8
    ISSN 0004-6981 ; 1352-2310
    ISSN 0004-6981 ; 1352-2310
    DOI 10.1016/j.atmosenv.2020.117428
    Database NAL-Catalogue (AGRICOLA)

    More links

    Kategorien

  9. Article: Reliable data from low cost ozone sensors in a hierarchical network

    Miskell, Georgia / Alberti, Kyle / Feenstra, Brandon / Henshaw, Geoff S / Papapostolou, Vasileios / Patel, Hamesh / Polidori, Andrea / Salmond, Jennifer A / Weissert, Lena / Williams, David E

    Elsevier Ltd Atmospheric environment. 2019 Oct. 01, v. 214

    2019  

    Abstract: We demonstrate how a hierarchical network comprising a number of compliant reference stations and a much larger number of low-cost sensors can deliver reliable high temporal-resolution ozone data at neighbourhood scales. The larger than expected spatial ... ...

    Abstract We demonstrate how a hierarchical network comprising a number of compliant reference stations and a much larger number of low-cost sensors can deliver reliable high temporal-resolution ozone data at neighbourhood scales. The larger than expected spatial and temporal variation of ozone in a heavily-trafficked urban environment is thereby demonstrated. The framework, demonstrated originally for a smaller scale regional network deployed in the Lower Fraser Valley, BC was tested and refined using two much more extensive networks of gas-sensitive semiconductor-based (GSS) sensors deployed at neighbourhood scales in Los Angeles: one of ~20 and one of ~45 GSS ozone sensors. Of these, ten sensors were co-located with different regulatory measurement stations, allowing a rigorous test of the accuracy of the algorithms used for off-site calibration and adjustment of low cost sensors. The method is based on adjusting the gain and offset of the low-cost sensor to match the first two moments of the probability distribution of the sensor result to that of a proxy: a calibrated independent measurement (usually derived from regulatory monitors) whose probability distribution evaluated over a time that emphasizes diurnal variations is similar to that at the test location. The regulatory measurement station physically closest to the low-cost sensor was a good proxy for most sites. The algorithms developed were successful in detecting and correcting sensor drift, and in identifying locations where geographical features resulted in significantly different patterns of ozone variation due to the relative dominance of different dispersion, emission and chemical processes. The entire network results show very large variations in ozone concentration that take place on short time- and distance scales across the Los-Angeles region. Such patterns were not captured by the more sparsely distributed stations of the existing regulatory network and demonstrate the need for reliable data from dense networks of monitors.
    Keywords algorithms ; atmospheric chemistry ; calibration ; diurnal variation ; ozone ; probability distribution ; urban areas
    Language English
    Dates of publication 2019-1001
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 216368-8
    ISSN 0004-6981 ; 1352-2310
    ISSN 0004-6981 ; 1352-2310
    DOI 10.1016/j.atmosenv.2019.116870
    Database NAL-Catalogue (AGRICOLA)

    More links

    Kategorien

  10. Book ; Online: Hierarchical network design for nitrogen dioxide measurement in urban environments, part 2

    Weissert, Lena / Miles, Elaine / Miskell, Georgia / Alberti, Kyle / Feenstra, Brandon / Henshaw, Geoff S / Papapostolou, Vasileios / Patel, Hamesh / Polidori, Andrea / Salmond, Jennifer A / Williams, David E

    network-based sensor calibration

    2019  

    Abstract: We present a management and data correction framework for low-cost electrochemical sensors for nitrogen dioxide (NO2) deployed within a hierarchical network of low-cost and regulatory-grade instruments. The framework is founded on the idea that it is ... ...

    Abstract We present a management and data correction framework for low-cost electrochemical sensors for nitrogen dioxide (NO2) deployed within a hierarchical network of low-cost and regulatory-grade instruments. The framework is founded on the idea that it is possible in a suitably configured network to identify a source of reliable proxy data for each sensor site that has a similar probability distribution of measurement values over a suitable time period. Previous work successfully applied these ideas to a sensor system with a simple linear 2-parameter (slope and offset) response. Applying these ideas to electrochemical sensors for NO2 presents significant additional difficulties for which we demonstrate solutions. The three NO2 sensor response parameters (offset, ozone (O3) response slope, and NO2 response slope) are known to vary significantly as a consequence of ambient humidity and temperature variations. Here we demonstrate that these response parameters can be estimated by minimising the Kullback-Leibler divergence between sensor-estimated and proxy NO2 distributions over a 3-day window. We then estimate an additional offset term by using co-location data. This offset term is dependent on climate and spatially correlated and can thus be projected across the network. Co-location data also estimates the time-, space- and concentration-dependent error distribution between sensors and regulatory-grade instruments. We show how the parameter variations can be used to indicate both sensor failure and failure of the proxy assumption. We apply the procedures to a network of 56 sensors distributed across the Inland Empire and Los Angeles County regions, demonstrating the need for reliable data from dense networks of monitors to supplement the existing regulatory networks.

    Comment: 40 pages inclusive of supporting information. 13 figure in main text; 15 figure in SI
    Keywords Statistics - Applications
    Subject code 333
    Publishing date 2019-11-08
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    More links

    Kategorien

To top