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Physiology & Behavior Feb 2015The aims of the present work were to investigate the relationships between radiant heat load, air velocity and body temperatures with or without coincidental exercise to...
The aims of the present work were to investigate the relationships between radiant heat load, air velocity and body temperatures with or without coincidental exercise to determine the physiological mechanisms that drive thermal comfort and thermoregulatory behaviour. Seven male volunteers wearing swimming trunks in 18°C, 22°C or 26°C air were exposed to increasing air velocities up to 3 m s(-1) and self-adjusted the intensity of the direct radiant heat received on the front of the body to just maintain overall thermal comfort, at rest or when cycling (60 W, 60 rpm). During the 30 min of the experiments, skin and rectal temperatures were continuously recorded. We hypothesized that mean body temperature should be maintained stable and the intensity of the radiant heat and the mean skin temperatures would be lower when cycling. In all conditions, mean body temperature was lower when facing winds of 3 m s(-1) than during the first 5 min, without wind. When facing winds, in all but the 26°C air, the radiant heat was statistically higher at rest than when exercising. In 26°C air mean skin temperature was lower at rest than when exercising. No other significant difference was observed. In all air temperatures, high correlation coefficients were observed between the air velocity and the radiant heat load. Other factors that we did not measure may have contributed to the constant overall thermal comfort status despite dropping mean skin and body temperatures. It is suggested that the allowance to behaviourally adjust the thermal environment increases the tolerance of cold discomfort.
Topics: Air; Bicycling; Body Temperature; Exercise; Humans; Male; Perception; Physical Stimulation; Rest; Temperature; Wind; Young Adult
PubMed: 25437244
DOI: 10.1016/j.physbeh.2014.11.064 -
Indoor Air Nov 2017We report measurements of hydroxyl (OH) and hydroperoxy (HO ) radicals made by laser-induced fluorescence spectroscopy in a computer classroom (i) in the absence of...
We report measurements of hydroxyl (OH) and hydroperoxy (HO ) radicals made by laser-induced fluorescence spectroscopy in a computer classroom (i) in the absence of indoor activities (ii) during desk cleaning with a limonene-containing cleaner (iii) during operation of a commercially available "air cleaning" device. In the unmanipulated environment, the one-minute averaged OH concentration remained close to or below the limit of detection (6.5×10 molecule cm ), whilst that of HO was 1.3×10 molecule cm . These concentrations increased to ~4×10 and 4×10 molecule cm , respectively during desk cleaning. During operation of the air cleaning device, OH and HO concentrations reached ~2×10 and ~6×10 molecule cm respectively. The potential of these OH concentrations to initiate chemical processing is explored using a detailed chemical model for indoor air (the INDCM). The model can reproduce the measured OH and HO concentrations to within 50% and often within a few % and demonstrates that the resulting secondary chemistry varies with the cleaning activity. Whilst terpene reaction products dominate the product composition following surface cleaning, those from aromatics and other VOCs are much more important during the use of the air cleaning device.
Topics: Air; Air Pollution, Indoor; Disinfection; Hydroxides; Models, Chemical; Oxygen; Peroxides; Volatile Organic Compounds
PubMed: 28493625
DOI: 10.1111/ina.12394 -
Environmental Science and Pollution... Dec 2016Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were studied to determine occurrence, levels and spatial distribution in the marine atmosphere and...
Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were studied to determine occurrence, levels and spatial distribution in the marine atmosphere and surface seawater during cruises in the German Bight and the wider North Sea in spring and summer 2009-2010. In general, the concentrations found in air are similar to, or below, the levels at coastal or near-coastal sites in Europe. Hexachlorobenzene and α-hexachlorocyclohexane (α-HCH) were close to phase equilibrium, whereas net atmospheric deposition was observed for γ-HCH. The results suggest that declining trends of HCH in seawater have been continuing for γ-HCH but have somewhat levelled off for α-HCH. Dieldrin displayed a close to phase equilibrium in nearly all the sampling sites, except in the central southwestern part of the North Sea. Here atmospheric deposition dominates the air-sea exchange. This region, close to the English coast, showed remarkably increased surface seawater concentrations. This observation depended neither on riverine input nor on the elevated abundances of dieldrin in the air masses of central England. A net depositional flux of p,p'-DDE into the North Sea was indicated by both its abundance in the marine atmosphere and the changes in metabolite pattern observed in the surface water from the coast towards the open sea. The long-term trends show that the atmospheric concentrations of DDT and its metabolites are not declining. Riverine input is a major source of PCBs in the German Bight and the wider North Sea. Atmospheric deposition of the lower molecular weight PCBs (PCB28 and PCB52) was indicated as a major source for surface seawater pollution.
Topics: Air; Air Pollutants; Atmosphere; England; Environmental Monitoring; Hydrocarbons, Chlorinated; North Sea; Pesticides; Polychlorinated Biphenyls; Seawater
PubMed: 27617333
DOI: 10.1007/s11356-016-7530-3 -
Sensors (Basel, Switzerland) Mar 2021This work concerns the performance analysis of the sensors contained in a victim detection system. The system is a mobile platform with gas sensors utilized for real...
This work concerns the performance analysis of the sensors contained in a victim detection system. The system is a mobile platform with gas sensors utilized for real time victim localization in urban environments after a disaster has caused the entrapment of people in partially collapsed building structures. The operating principle of the platform is the sampling of air from potential survival spaces (voids) and the measurement of the sampled air's temperature and concentration of CO and O. Humans in a survival space are modelled as sources of CO and heat and sinks of O. The physical openings of a survival space are modelled as sources of fresh air and sinks of the internal air. These sources and sinks dynamically affect the monitored properties of the air inside a survival space. In this paper, the effects of fresh air sources and internal air sinks are first examined in relation to local weather conditions. Then, the effect of human sources of CO and sinks of O in the space are examined. A model is formulated in order to reliably estimate the concentration of CO and O as a function of time for given reasonable entrapment scenarios. The input parameters are the local weather conditions, the openings of the survival space, and the number and type of entrapped humans. Three different tests successfully verified the presented theoretical estimations. A detection system with gas sensors of specified or measured capabilities, by utilizing this model and based on the expected concentrations, may inform the operator of the minimum required presence of humans in a survival space that can be detected after "some time".
Topics: Air; Carbon Dioxide; Humans
PubMed: 33809293
DOI: 10.3390/s21062018 -
Environmental Toxicology and Chemistry Sep 2017Superfund sites may be a source of polycyclic aromatic hydrocarbons (PAHs) to the surrounding environment. These sites can also act as PAH sinks from present-day...
Superfund sites may be a source of polycyclic aromatic hydrocarbons (PAHs) to the surrounding environment. These sites can also act as PAH sinks from present-day anthropogenic activities, especially in urban locations. Understanding PAH transport across environmental compartments helps to define the relative contributions of these sources and is therefore important for informing remedial and management decisions. In the present study, paired passive samplers were co-deployed at sediment-water and water-air interfaces within the Portland Harbor Superfund Site and the McCormick and Baxter Superfund Site. These sites, located along the Willamette River (Portland, OR, USA), have PAH contamination from both legacy and modern sources. Diffusive flux calculations indicate that the Willamette River acts predominantly as a sink for low molecular weight PAHs from both the sediment and the air. The sediment was also predominantly a source of 4- and 5-ring PAHs to the river, and the river was a source of these same PAHs to the air, indicating that legacy pollution may be contributing to PAH exposure for residents of the Portland urban center. At the remediated McCormick and Baxter Superfund Site, flux measurements highlight locations within the sand and rock sediment cap where contaminant breakthrough is occurring. Environ Toxicol Chem 2017;36:2281-2289. © 2017 SETAC.
Topics: Air; Cities; Geologic Sediments; Hazardous Waste Sites; Oregon; Polycyclic Aromatic Hydrocarbons; Rivers; Water; Water Pollutants, Chemical
PubMed: 28262984
DOI: 10.1002/etc.3785 -
Scientific Reports Sep 2022The interest around analysis of volatile organic compounds (VOCs) within breath has increased in the last two decades. Uncertainty remains around standardisation of...
The interest around analysis of volatile organic compounds (VOCs) within breath has increased in the last two decades. Uncertainty remains around standardisation of sampling and whether VOCs within room air can influence breath VOC profiles. To assess the abundance of VOCs within room air in common breath sampling locations within a hospital setting and whether this influences the composition of breath. A secondary objective is to investigate diurnal variation in room air VOCs. Room air was collected using a sampling pump and thermal desorption (TD) tubes in the morning and afternoon from five locations. Breath samples were collected in the morning only. TD tubes were analysed using gas chromatography coupled with time-of-flight mass spectrometry (GC-TOF-MS). A total of 113 VOCs were identified from the collected samples. Multivariate analysis demonstrated clear separation between breath and room air. Room air composition changed throughout the day and different locations were characterized by specific VOCs, which were not influencing breath profiles. Breath did not demonstrate separation based on location, suggesting that sampling can be performed across different locations without affecting results.
Topics: Air; Air Pollutants; Body Fluids; Breath Tests; Gas Chromatography-Mass Spectrometry; Volatile Organic Compounds
PubMed: 36151300
DOI: 10.1038/s41598-022-20365-7 -
The New Phytologist Aug 2014Elevated atmospheric CO2 concentration (eCO2) has the potential to increase vegetation carbon storage if increased net primary production causes increased long-lived... (Comparative Study)
Comparative Study
Elevated atmospheric CO2 concentration (eCO2) has the potential to increase vegetation carbon storage if increased net primary production causes increased long-lived biomass. Model predictions of eCO2 effects on vegetation carbon storage depend on how allocation and turnover processes are represented. We used data from two temperate forest free-air CO2 enrichment (FACE) experiments to evaluate representations of allocation and turnover in 11 ecosystem models. Observed eCO2 effects on allocation were dynamic. Allocation schemes based on functional relationships among biomass fractions that vary with resource availability were best able to capture the general features of the observations. Allocation schemes based on constant fractions or resource limitations performed less well, with some models having unintended outcomes. Few models represent turnover processes mechanistically and there was wide variation in predictions of tissue lifespan. Consequently, models did not perform well at predicting eCO2 effects on vegetation carbon storage. Our recommendations to reduce uncertainty include: use of allocation schemes constrained by biomass fractions; careful testing of allocation schemes; and synthesis of allocation and turnover data in terms of model parameters. Data from intensively studied ecosystem manipulation experiments are invaluable for constraining models and we recommend that such experiments should attempt to fully quantify carbon, water and nutrient budgets.
Topics: Air; Biomass; Carbon; Carbon Dioxide; Computer Simulation; Ecosystem; Forests; Models, Theoretical; Trees; Wood
PubMed: 24844873
DOI: 10.1111/nph.12847 -
Lab on a Chip Dec 2015A new approach to trap air bubbles before they enter microfluidic systems is presented. The bubble trap is based on the combined interaction of surface tension and...
A new approach to trap air bubbles before they enter microfluidic systems is presented. The bubble trap is based on the combined interaction of surface tension and hydrodynamic forces. The design is simple, easy to fabricate and straightforward to use. The trap is made of tubes of different sizes and can easily be integrated into any microfluidic setup. We describe the general working principle and derive a simple theoretical model to explain the trapping. Furthermore, the natural oscillations of trapped air bubbles created in this system are explained and quantified in terms of bubble displacement over time and oscillation frequency. These oscillations may be exploited as a basis for fluidic oscillators in future microfluidic systems.
Topics: Air; Equipment Design; Microfluidics; Time Factors
PubMed: 26500046
DOI: 10.1039/c5lc00592b -
PloS One 2019High amounts of aerial pollutants like dust and microorganisms can pose serious health hazards to animals and humans. The aim of the current study therefore was, to...
High amounts of aerial pollutants like dust and microorganisms can pose serious health hazards to animals and humans. The aim of the current study therefore was, to assess the efficiency of UVC irradiation combined to air filtration in reducing airborne microorganisms at laboratory scale. In a second part, a UVC-combined recirculating air filtration module (UVC module) was implemented in a small animal facility in order to assess its improvement of air quality with regard to airborne bacteria and dust. Tests at laboratory scale were performed using aerosols of Staphylococcus (S.) aureus, Actinobacillus pleuropneumoniae, porcine parvovirus (PPV) and porcine reproductive and respiratory syndrome virus. We varied relative humidity (RH) to evaluate its effect on UVC irradiation efficiency. In addition, viability of pathogens inside the filter material was determined over up to six months. UVC-combined air filtration resulted in a more than 99% reduction of viral and bacterial particles. RH had no influence on UVC efficiency. Viability in the filter matter varied depending on the pathogen used and RH with S. aureus and PPV being most resistant. In our small pig facility consisting of two separated barns, weekly air measurements were conducted over a period of 13 weeks (10 piglets) and 16 weeks (11 piglets), respectively. Airborne bacterial numbers were significantly lower in the barn equipped with the UVC module compared to the reference barn. On average a reduction to 37% of reference values could be achieved for bacteria, whereas the amount of total dust was reduced to a much lesser extent (i.e. to 78% of reference values). Measures taken in front of and behind the UVC module revealed a reduction of 99.4% for airborne bacteria and 95.0% for total dust. To conclude, recirculating air filtration combined to UVC provided efficient reduction of pathogens at laboratory and experimental scale. The implementation of such devices might improve the overall environmental quality in animal facilities.
Topics: Air; Air Microbiology; Air Pollution; Ammonia; Animals; Carbon Dioxide; Dust; Filtration; Housing, Animal; Humidity; Microbial Viability; Swine; Temperature; Ultraviolet Rays
PubMed: 31697778
DOI: 10.1371/journal.pone.0225047 -
Journal of Healthcare Engineering 2019Surgical lights in the operating rooms are typically installed in a single axis in the center of the room or in two axes on both sides of the operating table. In the...
PURPOSE
Surgical lights in the operating rooms are typically installed in a single axis in the center of the room or in two axes on both sides of the operating table. In the single-axis installation, the air-conditioning outlet cannot be placed in the center of the ceiling, which may affect the air current. Therefore, we measured the air current and cleanliness in two equivalent operating rooms using a vertical laminar airflow system equipped with either single-axis or double-axis surgical lights.
METHODS
Air current was measured using a three-dimensional ultrasonic anemometer. Cleanliness was evaluated by measuring the amount of dust before and after air-conditioner activation. To visualize the air current, smoke was illuminated on a sheet of laser light while the air-conditioning was stopped, and changes after air-conditioning activation were observed.
RESULTS
In the single-axis room, an oblique fast air current flowing from the surrounding air outlet toward the center was observed, and the flow velocity fluctuated greatly. In the double-axis room, uniform downward laminar airflow was observed. The amount of dust at the center decreased significantly faster in the double-axis room; thus, the cleanliness at the center was higher in the double-axis room. Persistent stagnation of smoke was observed below the single-axis lighting, whereas smoke below the double-axis lighting was immediately dispersed and the air cleared even when surgical lights were in the position for surgery.
CONCLUSION
Uniform vertical laminar airflow was formed and high cleanliness was achieved in the center of the room when the surgical lights were arranged in two axes.
Topics: Air; Environment, Controlled; Environmental Monitoring; Lighting; Operating Rooms
PubMed: 31049187
DOI: 10.1155/2019/4861273