Naturally occurring elongated mineral particles (EMPs) are microscopic particles derived from rocks and soils and are defined by their high aspect ratios. They include both asbestiform minerals, some of which are recognised carcinogens, and non-asbestiform minerals. While occupational exposure to commercially used EMPs such as asbestos has been extensively studied, population-scale exposure to naturally occurring EMPs in environmental settings remains poorly understood. Direct measurements of ambient EMP concentrations are rare due to their low abundance and the analytical difficulty of isolating fibres from complex ambient particulate matter. To address these challenges, a cost-effective, filter-based air-sampling network was established in Riverhead, Auckland, New Zealand, where erionite and other elongated mineral particles have been reported in local geology. A multi-tiered analytical workflow was applied, combining automated scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) for high-throughput screening with transmission electron microscopy and selected-area electron diffraction (TEM-SAED) for mineralogical confirmation. Automated SEM-EDS screening identified 449 EMPs across the sampled locations, of which 29 exhibited Si:Al ratios within the range characteristic of erionite. However, subsequent TEM-SAED analysis confirmed that none of these particles were erionite. These results indicate that airborne erionite was not detected in the analysed filters within the spatial and temporal scope and analytical detection limits of the monitoring campaign. The study demonstrates the utility of combining dense monitoring networks with automated SEM-based screening as a scalable framework for environmental EMP surveillance in regions where fibrous minerals occur in local geology.

Microplastics are an emerging class of contaminants that are widespread in the environment. While studies on airborne microplastics are rapidly increasing, the lack of standardised sampling and analysis methods is hindering progress towards accurately quantifying their global distribution. This study used existing analytical methodologies to understand the variability in identifying and quantifying airborne microplastics. High-volume aerosol samples were collected at a remote site in New Zealand and were analysed by micro-Fourier transform infrared spectroscopy, micro-Raman spectroscopy, Nile red staining combined with fluorescence microscopy, pyrolysis-gas chromatography/mass spectrometry and thermal desorption-proton transfer reaction-mass spectrometry, with all methods reporting different concentrations and polymer types. No particles were larger than 100 µm, and 98% of particles were smaller than 10 µm, highlighting the importance of methods that can analyse sub-10 µm particles. This study highlights the need for caution when comparing airborne microplastic datasets analysed using different methods.

Microplastics are an emerging class of contaminants that are widespread in the environment. While studies on airborne microplastics are rapidly increasing, the lack of standardised sampling and analysis methods is hindering progress towards accurately quantifying their global distribution. This study used existing analytical methodologies to understand the variability in identifying and quantifying airborne microplastics. High-volume aerosol samples were collected at a remote site in New Zealand and were analysed by micro-Fourier transform infrared spectroscopy, micro-Raman spectroscopy, Nile red staining combined with fluorescence microscopy, pyrolysis-gas chromatography/mass spectrometry and thermal desorption-proton transfer reaction-mass spectrometry, with all methods reporting different concentrations and polymer types. No particles were larger than 100 µm, and 98% of particles were smaller than 10 µm, highlighting the importance of methods that can analyse sub-10 µm particles. This study highlights the need for caution when comparing airborne microplastic datasets analysed using different methods.

Exposure to carcinogenic elongated mineral particles (EMPs), such as erionite, found in rocks and released into the air by construction, quarrying, or roading activities, poses a significant possible health risk due to their respirable size and potential for airborne dispersion. The detection of EMPs in the air is typically achieved by filter sampling and subsequent examination using a range of microscopic methods, including phase contrast microscopy (PCM) and scanning electron microscope (SEM). Such analyzes require the manual searching for fibers through many image fields and are both labor-intensive and time-consuming. Moreover, these methods do not result in conclusive particle identification, limiting their effectiveness in large-scale monitoring programmes. This paper introduces a novel methodology for the automated detection and quantification of EMPs using an automated SEM with energy dispersive spectroscopy (EDS) to identify fibers on pre-sampled polycarbonate (PC) filters. This method provides a streamlined workflow for fiber identification based on their size, morphology, and elemental composition. Performance evaluation (PE) standards were prepared by spiking filters with a series of known concentrations of one EMP, namely erionite, and fiber concentrations were measured using the automated SEM-EDS approach. Our results demonstrate a linear relationship (R2 = 0.98***) between the erionite mass percentage in a bulk sample and the fiber counts in an aerosolized air volume, with a detection limit of 7.4 f/cc. The approach can be optimized based on the time available for analysis and the choice of detection limit suitable for the specific site and application. Additionally, the automated SEM-EDS method has been applied to real-world air samples collected from Auckland, New Zealand, showing promising results for fiber detection in complex environmental matrices.

Urban air pollution is significantly influenced by road traffic, with recent research highlighting the growing significance of non-exhaust emissions (NEEs) such as road dust, brake wear, and tyre abrasion. While electric vehicles offer a pathway to reducing tailpipe emissions, their environmental benefits may be offset by increased NEEs, especially from heavier vehicle fleets. This study investigates the contribution of road dust to PM₁₀ concentrations in Auckland, New Zealand, using a 13-year panel dataset (2006-2019) from three strategically located air quality monitoring sites. PM₁₀ data were sourced from GNS Science and derived through receptor modelling, while traffic flow data were obtained from the New Zealand Transport Agency. Employing panel regression models with fixed effects, we quantify the influence of road dust, meteorological variables such as temperature and wind speed, and heavy vehicle traffic on PM₁₀ levels. Our findings demonstrate that road dust is a dominant and statistically significant contributor to PM₁₀, exceeding traditional tailpipe sources even in a relatively wet climate. The study offers robust empirical insights into the complex dynamics between NEEs, vehicle fleets, and meteorology, providing valuable guidance for policymakers seeking cost-effective and targeted strategies to improve urban air quality in the transition to sustainable transport systems.

Despite intensive research over the past three decades, a generally accepted standard method to measure black carbon (BC) or elemental carbon (EC) still does not exist. Data on BC and EC concentrations are method specific and can differ widely. This work was motivated by the lack of any prior study that established the variability between these two measures of carbonaceous particulate matter. Measurements of BC and EC were performed at different locations across Asia and the South Pacific in both urban and suburban locations. Filter samples were collected during the winter of 2007 to the winter of 2010 and analyzed for both BC and EC. EC was measured using the Interagency Monitoring of Protected Visual Environments (IMPROVE_A) protocol. Black carbon was measured by the EELS reflectometer (Diffusion Systems, Ltd). Bangladesh had the highest correlation coefficient of 0.93. Bangkok, Thailand on the other hand had the lowest correlation coefficient of 0.34. A review of previously reported source apportionment of BC concentrations in these locations showed that New Zealand had the highest percentage (82%) of BC from biomass while Mongolia had the lowest percentage of 3.1%. The fraction of BC emissions from diesel vehicles was found predominant in Mumbai, India with values as high as 80%. Mongolia had the lowest emission of BC from diesel vehicle (5.4%) with coal- and biomass-combustion being the dominant sources.

Particulates emitted from the ocean's surface such as sea salt and byproducts of marine biogenic activity form atmospheric aerosols. Aerosols are important for climate change because they have offset some of the historical warming caused by greenhouse gases. Aerosols are also significant for human health: they are small enough to be inhaled and contribute to respiratory problems and other illnesses. Marine aerosol is the primary source of natural aerosol present in urban areas of Aotearoa New Zealand and, as part of the natural aerosol background, cannot be managed. Here, we review the production and presence of marine aerosols in New Zealand's air, and the implications for human health and climate change. Because marine aerosol is sensitive to physical changes in climate such as sea surface temperature and winds, production is likely to be affected by climate change. Overall, marine aerosol is unlikely to become a smaller contributor to urban atmospheric aerosol loading in New Zealand towns and cities under future climate change scenarios. Continued assessment of anthropogenic aerosols will be necessary to ensure that air quality targets are met.

Erionite, a known carcinogenic zeolite, is prevalent in the rock strata below some parts of New Zealand. It is thought that erionite or other elongated mineral particles (EMPs) could be dispersed into the air at a concentration that is potentially harmful. Currently, there is limited understanding of the number of fibres entering the atmosphere or knowledge of the spatial variability of fibrous mineral concentrations across airsheds. It is not known if fibrous materials, when present in excavated material, are resuspended from roads and, if so, whether they remain in a ‘fibrous' form. To help answer these questions, this research describes an on-road vehicle measurement campaign involving the sampling of road dust using a portable device consisting of a pump fitted with a sampling filter. The device was fixed to a moving vehicle traveling along routes through townships currently experiencing significant levels of development and excavation activity. Erionite is known to exist close to the surface, and thus could potentially be liberated into the air during excavation. Excavated material which is transported along these routes also poses a risk. Filters were analyzed using a combination of microscopic techniques consisting of both visual morphology and elemental analysis. The methodology was successful in helping to identify EMPs, including what appears to be erionite, as well as fragments of other fibrous material within the resuspended road dust. The measurement technique could be used as a screening tool to identify areas where EMP's pose a potential risk due to excavation activity.

Worldwide, there is an increasing uptake of traffic management interventions aimed at reducing the impact of traffic related air pollution on public health. However, the evidence base linking the proposed changes with the resulting improvements in air quality is lacking. In this paper we present data from a micro-network of low-cost PM10 samplers collected from an isolated urban centre (Auckland, New Zealand). The data was then analysed using a new combination of analytical methods aimed to identify the composition and hence, the source of pollution. Whilst across the three sites mass concentration of PM10 and black carbon were similar, Raman spectroscopy successfully identified variations in the soot composition at different sites, enabling some particulate matter to be linked to diesel vehicle emissions. A mass reconstruction approach proved useful in determining that the airshed is well-mixed and also highlighted the impacts of urban design on recorded concentrations. The results show that networks of low-cost sensors, combined with the range of analytical techniques used here can help policymakers test the efficacy of interventions and management strategies designed to combat the burden of air pollution on public health.

Airborne particles and pollutant gases are of increasing concern due to their adverse health effects, necessitating a thorough understanding of their composition, sources, spatial and temporal trends for effective air quality management. This study is part of a source apportionment study in Auckland, a dynamic urban environment with complex air quality challenges in an isolated Southern Ocean setting. Over the 2006–2016 period, concentrations of PM2.5, CO, NO2, and SO2 consistently decreased at all 4 monitoring sites indicating the impacts of control measures. The sources impacting the four sites were identified using the positive matrix factorisation (PMF) receptor model. Common sources affecting these sites included motor vehicles (both petrol and diesel), biomass burning, sea salt, sulphate/marine diesel, and soil/road dust. While motor vehicle emissions and biomass burning emerged as the primary contributors to PM2.5, BC, NO2, CO, and SO2, motor vehicle contributions declined due to advancements in fuel formulation and engine technology despite increased vehicle numbers. Biomass burning contributed substantially to winter PM2.5 concentrations driven by domestic heating practices. However, the introduction of alternative heating technologies mitigated the upward trends in biomass burning emissions despite an increasing residential population. Soil/road dust contributions varied by site, influenced by meteorological conditions and local activities, with implications for site-specific air quality management. Sulphate/marine diesel concentrations exhibited seasonal variability, reflecting the impact of both shipping emissions and natural sources. Urban sulphate concentrations decreased due to regulations requiring the introduction of low-sulphur automotive gasoline and diesel fuels. Sea salt, a naturally occurring source, posed challenges for management efforts with concentrations trending downwards over time, possibly linked to climate patterns. This study's source apportionment analysis provides critical insights into Auckland's air quality. The findings inform policy development, air quality management, and health impact assessments, benefiting both the Auckland region and New Zealand as a whole. Ongoing monitoring and emissions reduction strategies, particularly targeting motor vehicles and biomass burning, are pivotal for enhancing air quality and public health in the region.

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.

Erionite is a fibrous zeolite found in the rock beneath parts of Auckland, New Zealand. As a known carcinogen that can be easily inhaled. it has been linked to the development of mesothelioma. It has a high degree of carcinogenicity due to the specific physical dimensions of the fibres, with certain sizes able to easily deposit deep in the lung tissue once inhaled. This project seeks to understand the extent to which erionite, once exposed, propagates in the ambient air in the form of dust and airborne fibres. The research is made challenging by the lack of standard methodological approaches to detect and quantify such fibres in airborne samples. Initial monitoring has been targeted on areas that have the combined attributes of rapid urban development (and thus excavation) and a confirmed presence of erionite in the rock strata beneath. The key sampling periods will be during the New Zealand summertime when warm temperatures and drier conditions prevail, increasing the potential for dust and fibre generation and buoyancy. The research findings from this project aim to develop a standard method for investigating erionite fibres in ambient air, including recommendations for the use and application of suitable screening methods, instrumentation and field site choice and instrument network density for given scenarios.

Firework displays produce large amounts of particulate matter (PM), contributing to poor air quality in local areas. Since short-term exposure to particulate matter correlates with increased mortality risks, these celebrations may impact both human health and the environment. Little is known about the particulate matter produced from recreational fireworks, as most studies have focused on professional large-scale events. In New Zealand, it is common for consumer fireworks to be ignited within residential areas during the Guy Fawkes celebration around 5 November. To better understand the contribution of individual fireworks on local air quality, ambient PM10 sampling was conducted in the 10 days surrounding Guy Fawkes Day in Auckland, New Zealand. These data were supplemented with measurements of firework emissions from 11 different individual products, including smoke bombs, sparklers, and Roman candles. Filter sampling results indicated that personal fireworks can contribute to ground level ambient air quality during celebrations, increasing ambient PM10 concentrations by 21.6 μg m−3 over a 12-h sampling period. The use of personal fireworks can expose consumers to PM10 concentrations much higher, up to 9.51 mg m−3 from individual sparkler use under worst-case scenario assumptions. The inhalation of sparkler emissions for just 8 min can lead to an exposure to PM10 mass greater than that from daily recommended limits (50 μg m−3 exposure over 24 h). X-ray fluorescence (XRF) analysis indicated that potassium (K) and strontium (Sr) can be used as tracers for local firework use and that arsenic (As) may be an important contaminant during Guy Fawkes celebrations. The PM from personal fireworks contained large amounts of chlorine (Cl), which may be indicative of perchlorate oxidizers. In addition, lead (Pb) was observed in the PM generated from two of the colored sparklers, which were marketed as “safer” alternatives to more explosive firework products.

The identification of indoor air pollutants is useful for exposure analysis and air quality management as we spend 80-90% of our time in built environments. We present the results from a study of i...

Multi-element reference materials (ME-RM) were prepared with 28 elements on polytetrafluoroethylene (PTFE) filters utilizing a custom aerosol deposition system and certified multi-element solutions designed to mimic atmospheric particulate composition. ME-RM were then distributed to eight participating laboratories who provided measurement results via X-ray fluorescence (XRF), particle induced X-ray emission (PIXE), and inductively coupled plasma mass spectrometry (ICP-MS). Lab-consensus loadings computed following an international methodology agreed well with a priori ones for Na, Al, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, As, Se, Rb, Sr, Cd, and Pb. The lab results were in good agreement with a priori reference loadings for S, K, Ca, V, Mn, Fe, Co, As, Se, Rb, Sr, Cd, and Pb. This work demonstrates the ability of the custom aerosol chamber to generate consistent reference filters that can be used for instrument calibration and quality control, interlaboratory comparison, and proficiency testing purposes, filling a much-needed gap hitherto lacking because of unavailability of suitable reference materials.

Timber treated with the anti-fungal chemical copper chrome arsenate is used extensively in the New Zealand building industry. While illegal, the burning of treated timber is commonplace in New Zealand and presents a health risk. Outdoor ambient monitoring of arsenic in airborne particulate matter in New Zealand has identified levels that exceed the maximum standards of 5.5 ng m−3 (annual average) at some urban locations. In this study, two-week-old beard hair samples were collected during the winter months to establish individual exposure to arsenic using Inductively Coupled Plasma-Mass Spectrometry. These results were then compared with questionnaire data about wood burner use for the two weeks prior to sampling, and spatial trends in arsenic from ambient monitoring. Results suggest that the burning of construction timber that may contain arsenic is associated with a higher level of arsenic in hair than those who burn logs or coal exclusively. There is no association between the area-level density of wood burners and arsenic levels but a significant correlation with individual household choice of fuel as well as the smell of wood smoke in the community, suggesting very localised influences. Strategies are needed to raise awareness of the risks of burning treated timber and to provide economically-viable alternatives.

The nitrogen isotopic composition (delta N-15) of atmospheric nitrate aerosols is determined by both the delta N-15 of its precursor, NOx emissions, and the isotopic fractionations during the atmospheric oxidation of NOx. However, the latter has not been well-understood nor quantified by field observations. In addition, the seasonal variations of this isotopic fractionation have not been determined. To better understand this isotopic fractionation process, in this study, we analyzed the delta N-15 of nitrate aerosols collected from June 30, 2015 to August 6, 2016 at Baring Head, New Zealand, where the sources of NOx are well-studied. Our results showed that the delta N-15 values in nitrate aerosols display a clear seasonal variation, with lower delta N-15 values (-12 parts per thousand to similar to-9 parts per thousand) in the summer (January to March) and higher delta N-15 values (0 parts per thousand to 3 parts per thousand) in the winter (June-August), while the delta N-15 values of NOx sources exhibit a narrow range of variation from-10.7 +/- 1.4 parts per thousand to-9.8 +/- 1.4 parts per thousand. We attribute this discrepancy to the significant and variable isotopic fractionations during the oxidation processes of NOx. We then quantified the isotopic fractionation during 1) the equilibrium and kinetic isotopic fractionations between NO and NO2; and 2) the oxidation of NO2 to nitrate. Our calculations suggest that at Baring Head, the seasonal variations in the oxidation pathways of NO2 are the main driver of the seasonal variations of nitrate delta N-15 values. Furthermore, the overall isotopic fractionation factors of the oxidation process determined by two models (Kinetic fractionation model and Equilibrium fractionation model) are generally lower in the summer (from +6.3 +/- 1.7 parts per thousand to +9.5 +/- 5.2 parts per thousand)and higher in the winter (from +15.8 +/- 1.9 parts per thousand to +17.0 +/- 2.4 parts per thousand).

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.

Eight institutes using 12 different instruments analyzed newly developed multi-element reference materials (RM) for atmospheric particulate matter (PM) measurements. These RM have the potential to fill a gap in the currently available quality assurance resources for element analysis of PM samples such as X-ray fluorescence and inductively-coupled plasma mass spectrometry. This study evaluates the performance of these new RM generated by the University of California, Davis. The methodological challenge was to determine the reference loadings on the RM. Gravimetry is the most robust method to determine the sample deposit mass but cannot be used for these RM because some solution components are volatile and result in unpredictable total mass loadings on the RM. Instead of using gravimetry, a single well-measured element, along with the assumption that the relative mass fractions in the solutions were maintained in the aerosol deposited on the filters, was used to determine the reference loadings on the RM. This assumption appears to be valid for most elements in the solutions; notable exceptions include volatile species such as chlorine and bromine. Results from the 12 different instruments in the inter-laboratory evaluation agreed very well with the reference loadings (adjusted R-2 > 0.9 and slope between 0.7 and 1.3) for 17 of the 28 elements. In many cases, one or two instruments did not meet the performance criteria, which points to individual instrument calibration problems. For the 11 elements that did not perform as well, development work continues, and this intercomparison helped identify and fix a source of contamination in the system used to create the RM.Copyright (c) 2019 American Association for Aerosol Research