An Indoor Air Quality Study of residential dwellings was carried out in Melbourne, Australia, and a subset of the data was analysed to investigate the effect of proximity to major roads on indoor air ...quality (IAQ). Seven-day measurements of PM
10, NO
2, benzene, toluene, ethylbenzene and xylenes, along with continuous CO and PM
2.5 measurements were utilised. The measurements were made indoors and outdoors in 27 dwellings; 15 Near Road (<50
m from a major road) and 12 Far Road (>300
m from a major road). Dwellings were sampled for one week each in Winter/Spring 2008 and Summer/Autumn 2009, over an eight month period. Analysis of 7-day measurements showed that NO
2 and toluene were elevated at the 5% significance level both indoors and outdoors at Near Road Dwellings compared to Far Road Dwellings. Indoor/Outdoor (I/O) ratios of NO
2 and toluene were not significantly different between Near and Far Road dwellings giving no evidence of any anomalous dominant indoor source for NO
2 and toluene in Near Road dwellings. Indoor NO
2 was significantly correlated to gas stovetop and oven use in both Near and Far Road dwellings. In the absence of gas cooking, indoor NO
2 was elevated in Near Road dwellings relative to Far Road dwellings by approximately 4
ppb and this can be attributed to infiltration of outdoor air. I/O ratios for NO
2 were <1 for Near and Far Road dwellings, indicating that outdoor NO
2, and hence roadway emissions can potentially contribute a significant proportion to the indoor NO
2 concentration. Mean toluene I/O ratios were >2 indicating that indoor sources dominate with minor contribution from outdoors. Hence the relative contribution of roadways to indoor NO
2 is potentially greater than the relative contribution of roadways to indoor toluene. Findings elsewhere suggest that a similar outdoor enhancement of traffic related NO
2 (∼5
ppb) increases risk of lung cancer and childhood asthma (
Brauer et al., 2000; Nyberg et al., 2000). A simple conceptual model indicated spatial and temporal variance in the concentrations was the biggest limitation in detecting roadway influence outside Near Road dwellings for PM
10, PM
2.5 and NO
2 while measurement uncertainty was also important for CO.
► Elevated indoor NO
2 and toluene at Near Road dwellings attributed to road emissions. ► Road emissions contribute a significant proportion to indoor NO
2 concentrations. ► Road emissions contribute a minor proportion to the indoor toluene concentrations. ► Elevated NO
2 in Near Road dwellings likely to result in adverse health effects. ► Conceptual model explores spatial, temporal variance in background concentrations.
Aerosols deposited into the Great Barrier Reef (GBR) contain iron (Fe) and other trace metals, which may act as micronutrients or as toxins to this sensitive marine ecosystem. In this paper, we ...quantified the atmospheric deposition of Fe and investigated aerosol sources in Mission Beach (Queensland) next to the GBR. Leaching experiments were applied to distinguish pools of Fe with regard to its solubility. The labile Fe concentration in aerosols was 2.3–10.6 ng m−3, which is equivalent to 4.9%–11.4% of total Fe and was linked to combustion and biomass burning processes, while total Fe was dominated by crustal sources. A one-day precipitation event provided more soluble iron than the average dry deposition flux, 0.165 and 0.143 μmol m−2 day−1, respectively. Scanning Electron Microscopy indicated that alumina-silicates were the main carriers of total Fe and samples affected by combustion emissions were accompanied by regular round-shaped carbonaceous particulates. Collected aerosols contained significant amounts of Cd, Co, Cu, Mo, Mn, Pb, V, and Zn, which were mostly (47.5%–96.7%) in the labile form. In this study, we provide the first field data on the atmospheric delivery of Fe and other trace metals to the GBR and propose that this is an important delivery mechanism to this region.
In-situ marine cloud droplet number concentrations (CDNCs), cloud condensation nuclei (CCN), and CCN proxies, based on particle sizes and optical properties, are accumulated from seven field ...campaigns: ACTIVATE; NAAMES; CAMP2EX; ORACLES; SOCRATES; MARCUS; and CAPRICORN2. Each campaign involves aircraft measurements, ship-based measurements, or both. Measurements collected over the North and Central Atlantic, Indo-Pacific, and Southern Oceans, represent a range of clean to polluted conditions in various climate regimes. With the extensive range of environmental conditions sampled, this data collection is ideal for testing satellite remote detection methods of CDNC and CCN in marine environments. Remote measurement methods are vital to expanding the available data in these difficult-to-reach regions of the Earth and improving our understanding of aerosolcloud interactions. The data collection includes particle composition and continental tracers to identify potential contributing CCN sources. Several of these campaigns include High Spectral Resolution Lidar (HSRL) and polarimetric imaging measurements and retrievals that will be the basis for the next generation of space-based remote sensors and, thus, can be utilized as satellite surrogates.
Weather and climate models are challenged by uncertainties and biases in simulating Southern Ocean (SO) radiative fluxes that trace to a poor understanding of cloud, aerosol, precipitation, and ...radiative processes, and their interactions. Projects between 2016 and 2018 used in situ probes, radar, lidar, and other instruments to make comprehensive measurements of thermodynamics, surface radiation, cloud, precipitation, aerosol, cloud condensation nuclei (CCN), and ice nucleating particles over the SO cold waters, and in ubiquitous liquid and mixed-phase clouds common to this pristine environment. Data including soundings were collected from the NSF–NCAR G-V aircraft flying north–south gradients south of Tasmania, at Macquarie Island, and on the R/V Investigator and RSV Aurora Australis. Synergistically these data characterize boundary layer and free troposphere environmental properties, and represent the most comprehensive data of this type available south of the oceanic polar front, in the cold sector of SO cyclones, and across seasons. Results show largely pristine environments with numerous small and few large aerosols above cloud, suggesting new particle formation and limited long-range transport from continents, high variability in CCN and cloud droplet concentrations, and ubiquitous supercooled water in thin, multilayered clouds, often with small-scale generating cells near cloud top. These observations demonstrate how cloud properties depend on aerosols while highlighting the importance of dynamics and turbulence that likely drive heterogeneity of cloud phase. Satellite retrievals confirmed low clouds were responsible for radiation biases. The combination of models and observations is examining how aerosols and meteorology couple to control SO water and energy budgets.
Environmental cycling of the toxic metal mercury (Hg) is ubiquitous, and still not completely understood. Volatilisation and emission of mercury from vegetation, litter and soil during burning ...represents a significant return pathway for previously-deposited atmospheric mercury. Rates of such emission vary widely across ecosystems as they are dependent on species-specific uptake of atmospheric mercury as well as fire return frequencies. Wildfire burning in Australia is currently thought to contribute between 1 and 5% of the global total of mercury emissions, yet no modelling efforts to date have utilised local mercury emission factors (mass of emitted mercury per mass of dry fuel) or local mercury emission ratios (ratio of emitted mercury to another emitted species, typically carbon monoxide). Here we present laboratory and field investigations into mercury emission from burning of surface fuels in dry sclerophyll forests, native to the temperate south-eastern region of Australia. From laboratory data we found that fire behaviour — in particular combustion phase — has a large influence on mercury emission and hence emission ratios. Further, emission of mercury was predominantly in gaseous form with particulate-bound mercury representing <1% of total mercury emission. Importantly, emission factors and emission ratios with respect to carbon monoxide and carbon dioxide, from both laboratory and field data all show that gaseous mercury emission from biomass burning in Australian dry sclerophyll forests is currently overestimated by around 60%. Based on these results, we recommend a mercury emission factor of 28.7 ± 8.1 μg Hg kg−1 dry fuel, and emission ratio of gaseous elemental mercury relative to carbon monoxide of 0.58 ± 0.01 × 10−7, for estimation of mercury release from the combustion of Australian dry sclerophyll litter.
•Wildfire mercury release from eucalypt forests is currently overestimated by 60%.•Under natural wildfire fuel moistures, 99% of release is elemental mercury.•Fire progression impacts heavily; most mercury is released during flaming stage.•Recommended emission ratio for GEM/CO is 0.58 ± 0.01 × 10−7.
As part of a pilot study into the chemical and physical properties of Australian fine particles, a suite of aerosol samples was collected at Ti Tree Bend in Launceston, Tasmania, during June and July ...1997. This period represents midwinter in the Southern Hemisphere, a period when aerosol sources in Launceston are dominated by smoke from domestic wood burning. This paper describes the results from this measurement campaign, with the aim of assessing the effect of wood smoke on the chemical and physical characteristics of ambient aerosol. A micro orifice uniform deposit impactor (MOUDI) was used to measure the size distributions of the aerosol from 0.05 to 20 n m aerodynamic diameter. Continuous measurements of fine particle mass were made using a PM
2.5
tapered element oscillating microbalance (TEOM) and light scattering coefficients at 530 nm were measured with nephelometers.
Mass size distributions tended to be bimodal, with the diameter of the dominant mode tending to smaller sizes with increases in total mass. Non-sea salt potassium and polycyclic aromatic hydrocarbons (PAHs) were used as chemical tracers for wood smoke. Wood smoke was found to increase absolute particle mass (enough to regularly exceed air quality standards), and to concentrate mass in a single mode below 1 μm aerodynamic diameter. The acid-base equilibrium of the aerosol was altered by the wood smoke source, with free acidity hydrogen ion, non-sea salt sulfate, and ammonium concentrations being higher and the concentration of all species, including nitrate (to differing extents), focused in the fine particle size ranges. The wood smoke source also heavily influenced the aerosol scattering efficiency, adding to a strong diurnal cycle in both mass concentration and light scattering.
Volatility‐hygroscopicity tandem differential mobility analyzer measurements were used to infer the composition of sub‐100 nm diameter Southern Ocean marine aerosols at Cape Grim in November and ...December 2007. This study focuses on a short‐lived high sea spray aerosol (SSA) event on 7–8 December with two externally mixed modes in the Hygroscopic Growth Factor (HGF) distributions (90% relative humidity (RH)), one at HGF > 2 and another at HGF~1.5. The particles with HGF > 2 displayed a deliquescent transition at 73–75% RH and were nonvolatile up to 280°C, which identified them as SSA particles with a large inorganic sea‐salt fraction. SSA HGFs were 3–13% below those for pure sea‐salt particles, indicating an organic volume fraction (OVF) of up to 11–46%. Observed high inorganic fractions in sub‐100 nm SSA is contrary to similar, earlier studies. HGFs increased with decreasing particle diameter over the range 16–97 nm, suggesting a decreased OVF, again contrary to earlier studies. SSA comprised up to 69% of the sub‐100 nm particle number, corresponding to concentrations of 110–290 cm−3. Air mass back trajectories indicate that SSA particles were produced 1500 km, 20–40 h upwind of Cape Grim. Transmission electron microscopy (TEM) and X‐ray spectrometry measurements of sub‐100 nm aerosols collected from the same location, and at the same time, displayed a distinct lack of sea salt. Results herein highlight the potential for biases in TEM analysis of the chemical composition of marine aerosols.
Key Points
Characterization of high‐concentration sea spray aerosol event
Sub‐100 nm SSA organic volume fraction of up to 11–46% and size independent
Free tropospheric entrainment coincided with enhanced SSA concentrations
Millions of people can potentially be exposed to smoke from forest fires, making this an important public health problem in many countries.
In this study we aimed to measure the association between ...out-of-hospital cardiac arrest (OHCA) and forest fire smoke exposures in a large city during a severe forest fire season, and estimate the number of excess OHCAs due to the fire smoke.
We investigated the association between particulate matter (PM) and other air pollutants and OHCA using a case-crossover study of adults (≥ 35 years of age) in Melbourne, Australia. Conditional logistic regression models were used to derive estimates of the percent change in the rate of OHCA associated with an interquartile range (IQR) increase in exposure. From July 2006 through June 2007, OHCA data were collected from the Victorian Ambulance Cardiac Arrest Registry. Hourly air pollution concentrations and meteorological data were obtained from a central monitoring site.
There were 2,046 OHCAs with presumed cardiac etiology during our study period. Among men during the fire season, greater increases in OHCA were observed with IQR increases in the 48-hr lagged PM with diameter ≤ 2.5 μm (PM2.5) (8.05%; 95% CI: 2.30, 14.13%; IQR = 6.1 μg/m(3)) or ≤ 10 μm (PM10) (11.1%; 95% CI: 1.55, 21.48%; IQR = 13.7 μg/m(3)) and carbon monoxide (35.7%; 95% CI: 8.98, 68.92%; IQR = 0.3 ppm). There was no significant association between the rate of OHCA and air pollutants among women. One hundred seventy-four "fire-hours" (i.e., hours in which Melbourne's air quality was affected by forest fire smoke) were identified during 12 days of the 2006/2007 fire season, and 23.9 (95% CI: 3.1, 40.2) excess OHCAs were estimated to occur due to elevations in PM2.5 during these fire-hours.
This study found an association between exposure to forest fire smoke and an increase in the rate of OHCA. These findings have implications for public health messages to raise community awareness and for planning of emergency services during forest fire seasons.
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