Egg banking in anticipation of age-related fertility decline : using medical technology for better, not for worse

<p><b>Particle size distributions as measured by the SMPS for a) Cigarette smoke particles b) Petrol exhaust particles.</b> The respective number size distributions for different times were aggregated to the total size distribution.</p

Data_Sheet_1_Increasing ventilation reduces SARS-CoV-2 airborne transmission in schools: A retrospective cohort study in Italy's Marche region.docx

IntroductionWhile increasing the ventilation rate is an important measure to remove inhalable virus-laden respiratory particles and lower the risk of infection, direct validation in schools with population-based studies is far from definitive.MethodsWe investigated the strength of association between ventilation and SARS-CoV-2 transmission reported among the students of Italy's Marche region in more than 10,000 classrooms, of which 316 were equipped with mechanical ventilation. We used ordinary and logistic regression models to explore the relative risk associated with the exposure of students in classrooms.Results and discussionFor classrooms equipped with mechanical ventilation systems, the relative risk of infection of students decreased at least by 74% compared with a classroom with only natural ventilation, reaching values of at least 80% for ventilation rates >10 L s−1 student−1. From the regression analysis we obtained a relative risk reduction in the range 12?% for each additional unit of ventilation rate per person. The results also allowed to validate a recently developed predictive theoretical approach able to estimate the SARS-CoV-2 risk of infection of susceptible individuals via the airborne transmission route. We need mechanical ventilation systems to protect students in classrooms from airborne transmission; the protection is greater if ventilation rates higher than the rate needed to ensure indoor air quality (>10 L s−1 student−1) are adopted. The excellent agreement between the results from the retrospective cohort study and the outcome of the predictive theoretical approach makes it possible to assess the risk of airborne transmission for any indoor environment.</p

Effect of Cabin Ventilation Rate on Ultrafine Particle Exposure Inside Automobiles

We alternately measured on-road and in-vehicle ultrafine (2 = 0.81). UFP concentrations recorded in-cabin during tunnel travel were significantly higher than those reported by comparable studies performed on open roadways. A simple mathematical model afforded the ability to predict tunnel trip average in-cabin UFP concentrations with good accuracy. Our data indicate that under certain conditions, in-cabin UFP exposures incurred during tunnel travel may contribute significantly to daily exposure. The UFP exposure of automobile occupants appears strongly related to their choice of ventilation setting and vehicle

Diesel Bus Emissions Measured in a Tunnel Study

The emission factors of a bus fleet consisting of approximately 300 diesel-powered buses were measured in a tunnel study under well-controlled conditions during a 2-d monitoring campaign in Brisbane. Particle number and mass concentration levels of submicrometer particles and PM2.5 were monitored by SMPS and DustTrak instruments at the tunnel's entrance and exit, respectively. Correlation between DustTrak and TEOM response to diesel emissions was assessed, and the DustTrak results were recalculated into TEOM equivalent data. The mean value of the number and mass emission factors was (3.11±2.41) × 1014 particles km-1 for submicrometer particles and 583±451 mg km-1 for PM2.5 (DustTrak), respectively. TEOM PM2.5 equivalent emission factor was 267 ± 207 mg km-1. The results are in good agreement with the emission factors determined from steady-state dynamometer testing of 12 buses from the same Brisbane City bus fleet. The results indicate that when carefully designed, both approaches, the dynamometer and on-road studies, can provide comparable results, applicable for the assessment of the effect of traffic emissions on airborne particle pollution. A brief overview of emission factors determined from other on-road and dynamometer studies reported in the literature as well as with the regulatory values used for the vehicle emission inventory assessment is presented and compared with the results obtained in this study

Application of Multicriteria Decision Making Methods to Air Quality in the Microenvironments of Residential Houses in Brisbane, Australia

This paper reports the first application of the multicriteria decision making methods, PROMETHEE and GAIA, to indoor and outdoor air quality data. Fourteen residential houses in a suburb of Brisbane, Australia were investigated for 21 air quality-influencing criteria, which included the characteristics of the houses as well as the concentrations of volatile organic compounds, fungi, bacteria, submicrometer, and supermicrometer particles in their indoor and outdoor air samples. Ranking information necessary to select one house in preference to all others and to assess the parameters influencing the differentiation of the houses was found with the aid of PROMETHEE and GAIA. There was no correlation between the rank order of each house and the health complaints of its occupants. Patterns in GAIA plots show that indoor air quality in these houses is strongly dependent on the characteristics of the houses (construction material, distance of the house from a major road, and the presence of an in-built garage). Marked similarities were observed in the patterns obtained when GAIA and factor analysis were applied to the data. This underscores the potential of PROMETHEE and GAIA to provide information that can assist source apportionment and elucidation of effective remedial measures for indoor air pollution

Quantification of Particle Number and Mass Emission Factors from Combustion of Queensland Trees

The quantification of particle emission factors under controlled laboratory conditions for burning of the following five common tree species found in South East Queensland forests has been studied:  Spotted Gum (Corymbia citriodora), Blue Gum (Eucalyptus tereticornis), Bloodwood (Eucalyptus intermedia), Iron Bark (Eucalyptus crebra), and Stringybark (Eucalyptus umbra). The results of the study show that the particle number emission factors and PM2.5 mass emission factors depend on the type of tree and the burning rate. For fast burning conditions, the average particle number emission factors are in the range of 3.3−5.7 × 1015 particles/kg for woods and 0.5−6.9 × 1015 particles/kg for leaves and branches, and the PM2.5 emission factors are in the range of 140−210 mg/kg for woods and 450−4700 mg/kg for leaves and branches. For slow burning conditions, the average particle number emission factors are in the range of 2.8−44.8 × 1013 particles/kg for woods and 0.5−9.3 × 1013 particles/kg for leaves and branches, and the PM2.5 emissions factors are in the range of 120−480 mg/kg for woods and 3300−4900 mg/kg for leaves and branches

Vacuum Cleaner Emissions as a Source of Indoor Exposure to Airborne Particles and Bacteria

Vacuuming can be a source of indoor exposure to biological and nonbiological aerosols, although there are few data that describe the magnitude of emissions from the vacuum cleaner itself. We therefore sought to quantify emission rates of particles and bacteria from a large group of vacuum cleaners and investigate their potential determinants, including temperature, dust bags, exhaust filters, price, and age. Emissions of particles between 0.009 and 20 μm and bacteria were measured from 21 vacuums. Ultrafine (6 to 1.1 × 1011 particles min–1. Emission of 0.54–20 μm particles ranged from 4.0 × 104 to 1.2 × 109 particles min–1. PM2.5 emissions were between 2.4 × 10–1 and 5.4 × 103 μg min–1. Bacteria emissions ranged from 0 to 7.4 × 105 bacteria min–1 and were poorly correlated with dust bag bacteria content and particle emissions. Large variability in emission of all parameters was observed across the 21 vacuums, which was largely not attributable to the range of determinant factors we assessed. Vacuum cleaner emissions contribute to indoor exposure to nonbiological and biological aerosols when vacuuming, and this may vary markedly depending on the vacuum used

Dynamics and Viability of Airborne Respiratory Syncytial Virus under Various Indoor Air Conditions

The factors governing the viability of airborne viruses embedded within respiratory particles are not well understood. This study aimed to investigate the relative humidity (RH)-dependent viability of airborne respiratory syncytial virus (RSV) in simulated respiratory particles suspended in various indoor air conditions. We tested airborne RSV viability in three static indoor air conditions, including sub-hysteresis (RH < 39%), hysteresis (39% < RH < 65%), and super-hysteresis (RH > 65%) air as well as in three dynamic indoor air conditions, including the transitions between the static conditions. The dynamic conditions were hysteresis → super-hysteresis → hysteresis, sub-hysteresis → hysteresis, and super-hysteresis → hysteresis. We found that after 45 min of particle aging in static conditions, the viability of RSV in sub-hysteresis, hysteresis, and super-hysteresis air was 0.72% ± 0.06%, 0.03% ± 0.006%, and 0.27% ± 0.008%, respectively. After 45 min of aging in dynamic conditions, the RSV viability decreased for particles that remained in a liquid (deliquesced) state during aging when compared with particles in a solid (effloresced) state. The decreased viability of airborne RSV for deliquesced particles is consistent with prolonged exposure to elevated aqueous solutes. These results represent the first measurements of the survival of airborne RSV over particle aging time, with equal viability in low, intermediate, and high RHs at 5 and 15 min and a V-shaped curve after 45 min

Composition and Morphology of Particle Emissions from in-use Aircraft during Takeoff and Landing

In order to provide realistic data for air pollution inventories and source apportionment at airports, the morphology and composition of ultrafine particles (UFP) in aircraft engine exhaust were measured and characterized. For this purpose, two independent measurement techniques were employed to collect emissions during normal takeoff and landing operations at Brisbane Airport, Australia. PM₁ emissions in the airfield were collected on filters and analyzed using the particle-induced X-ray emission (PIXE) technique. Morphological and compositional analyses of individual ultrafine particles in aircraft plumes were performed on silicon nitride membrane grids using transmission electron microscopy (TEM) combined with energy-dispersive X-ray microanalysis (EDX). TEM results showed that the deposited particles were in the range of 5–100 nm in diameter, had semisolid spherical shapes and were dominant in the nucleation mode (18–20 nm). The EDX analysis showed the main elements in the nucleation particles were C, O, S, and Cl. The PIXE analysis of the airfield samples was generally in agreement with the EDX in detecting S, Cl, K, Fe, and Si in the particles. The results of this study provide important scientific information on the toxicity of aircraft exhaust and their impact on local air quality

Quantification of Particle Number and Mass Emission Factors from Combustion of Queensland Trees

The quantification of particle emission factors under controlled laboratory conditions for burning of the following five common tree species found in South East Queensland forests has been studied:  Spotted Gum (Corymbia citriodora), Blue Gum (Eucalyptus tereticornis), Bloodwood (Eucalyptus intermedia), Iron Bark (Eucalyptus crebra), and Stringybark (Eucalyptus umbra). The results of the study show that the particle number emission factors and PM2.5 mass emission factors depend on the type of tree and the burning rate. For fast burning conditions, the average particle number emission factors are in the range of 3.3−5.7 × 1015 particles/kg for woods and 0.5−6.9 × 1015 particles/kg for leaves and branches, and the PM2.5 emission factors are in the range of 140−210 mg/kg for woods and 450−4700 mg/kg for leaves and branches. For slow burning conditions, the average particle number emission factors are in the range of 2.8−44.8 × 1013 particles/kg for woods and 0.5−9.3 × 1013 particles/kg for leaves and branches, and the PM2.5 emissions factors are in the range of 120−480 mg/kg for woods and 3300−4900 mg/kg for leaves and branches