Impact of different supply air and recirculating air filtration systems on stable climate, animal health, and performance of fattening pigs in a commercial pig farm

Biosecurity is defined as the implementation of measures that reduce the risk of disease agents being introduced and/or spread. For pig production, several of these measures are routinely implemented (e.g. cleaning, disinfection, segregation). However, air as a potential vector of pathogens has long been disregarded. Filters for incoming and recirculating air were installed into an already existing ventilation plant at a fattening piggery (3,840 pigs at maximum) in Saxony, Germany. Over a period of three consecutive fattening periods, we evaluated various parameters including air quality indices, environmental and operating parameters, and pig performance. Animal data regarding respiratory diseases, presence of antibodies against influenza A viruses, PRRSV, and Actinobacillus pleuropneumoniae and lung health score at slaughter were recorded, additionally. There were no significant differences (p = 0.824) in total bacterial counts between barns with and without air filtration. Recirculating air filtration resulted in the lowest total dust concentration (0.12 mg/m³) and lung health was best in animals from the barn equipped with recirculating air filtration modules. However, there was no difference in animal performance. Antibodies against all above mentioned pathogens were detected but mostly animals were already antibody-positive at re-stocking. We demonstrated that supply air filtration as well as recirculating air filtration technique can easily be implemented in an already existing ventilation system and that recirculating air filtration resulted in enhanced lung health compared to supply air-filtered and non-filtered barns. A more prominent effect might have been obtained in a breeding facility because of the longer life span of sows and a higher biosecurity level with air filtration as an add-on measure.

Intrapulmonary percussive ventilation improves lung function in cystic fibrosis patients chronically colonized with Pseudomonas aeruginosa: a pilot cross-over study

High levels of shear stress can prevent and disrupt Pseudomonas aeruginosa biofilm formation in vitro. Intrapulmonary percussive ventilation (IPV) could be used to introduce shear stress into the lungs of cystic fibrosis (CF) patients to disrupt biofilms in vivo. We performed a first-of-its-kind pilot clinical study to evaluate short-term IPV therapy at medium (200 bursts per minute, bpm) and high frequency (400 bpm) as compared to autogenic drainage (AD) on lung function and the behavior of P. aeruginosa in the CF lung in four patients who are chronically colonized by P. aeruginosa. A significant difference between the three treatment groups was observed for both the forced expiratory volume in 1 s (FEV1) and the forced vital capacity (FVC) (p < 0.05). More specifically, IPV at high frequency significantly increased FEV1 and FVC compared to AD (p < 0.05) and IPV at medium frequency (p < 0.001). IPV at high frequency enhanced the expression levels of P. aeruginosa planktonic marker genes, which was less pronounced with IPV at medium frequency or AD. In conclusion, IPV at high frequency could potentially alter the behavior of P. aeruginosa in the CF lung and improve lung function.

TRIAL REGISTRATION

The trail was retrospectively registered at the ISRCTN registry on 6 June 2013, under trial registration number ISRCTN75391385.

Window/door opening-mediated bedroom ventilation and its impact on sleep quality of healthy, young adults

This work examined window/door opening as means of bedroom ventilation and the consequent effect upon occupants' sleep, using data from 17 healthy volunteers. Bedroom CO₂ level, temperature, and relative humidity were measured over 5 days, for two cases: open window or door (internal, bedroom door), and closed window and door. Participant filled questionnaires and sleep diary provided subjective measure of sleep quality. Actigraphy objectively monitored the participants during sleep. Additionally, a FlexSensor, placed under pillows of participants, detected movement during sleep. Average CO₂ level for the Open conditions was 717 ppm (SD = 197 ppm) and for Closed conditions was 1150 ppm (SD = 463 ppm). Absolute humidity levels were similar for both conditions, while Open conditions were slightly cooler (mean = 19.7°C, SD = 1.8°C) than Closed (mean = 20.1°C, SD = 1.5°C). Results showed significant correlations (P < .001) between actigraphy data and questionnaire responses for: sleep latency (r = .45), sleep length (r = .87), and number of awakenings (r = .28). Of all analyzed sleep parameters, questionnaire-based depth of sleep (P = .002) and actigraphy-based sleep phase (P = .003) were significantly different between Open and Closed conditions.

Effect of ventilation rate on air cleanliness and energy consumption in operation rooms at rest

The interrelationships between ventilation rate, indoor air quality, and energy consumption in operation rooms at rest are yet to be understood. We investigate the effect of ventilation rate on indoor air quality indices and energy consumption in ORs at rest. The study investigates the air temperature, relative humidity, concentrations of carbon dioxide, particulate matter (PM), and airborne bacteria at different ventilation rates in operation rooms at rest of a medical center. The energy consumption and cost analysis of the heating, ventilating, and air conditioning (HVAC) system in the operation rooms at rest were also evaluated for all ventilation rates. No air-conditioned operation rooms had very highest PM and airborne bacterial concentrations in the operation areas. The bacterial concentration in the operation areas with 6-30 air changes per hour (ACH) was below the suggested level set by the United Kingdom (UK) for an empty operation room. A 70% of reduction in annual energy cost by reducing the ventilation rate from 30 to 6 ACH was found in the operation rooms at rest. Maintenance of operation rooms at ventilation rate of 6 ACH could save considerable amounts of energy and achieve the goal of air cleanliness.

A case report of personal exposures to isoflurane during animal anesthesia procedures

The purpose of this study was to compare personal exposures to isoflurane from participants' breathing zone samples during animal anesthesia procedures by the method of anesthetic gas delivery and the waste anesthetic gas (WAG) control method utilized. WAG control methods included passive scavenging using charcoal canisters, active scavenging using a building vacuum system, and various local exhaust ventilation systems such as laboratory fume hoods and capture hoods. Methods of anesthesia delivery included induction chambers, face masks (also known as nose cones), and intubation. Personal breathing zone samples were collected using 3M 3520 Organic Vapor Diffusion Monitors and submitted to an International Organization for Standardization (ISO) 17025 accredited laboratory for analysis. When using face masks and induction chambers as the method of anesthesia delivery, local exhaust ventilation systems were found to be the best WAG control method to mitigate personal exposures to isoflurane. Personal exposures to isoflurane were well-controlled when animals were intubated, regardless of whether passive scavenging with an adsorptive charcoal canister or active scavenging with a building vacuum system was used. Personal exposures to isoflurane were highest when induction chambers and face masks were used for anesthesia delivery, and passive scavenging with adsorptive charcoal canisters were used as the control method. This study served to identify best practice WAG control methods for research and veterinary procedures that involve isoflurane anesthesia.

Characterization of wood dust emission from hand-held woodworking machines

This article focuses on the prevention of exposure to wood dust when operating electrical hand-held sawing and sanding machines. A laboratory methodology was developed to measure the dust concentration around machines during operating processes. The main objective was to characterize circular saws and sanders, with the aim of classifying the different power tools tested in terms of dust emission (high dust emitter vs. low dust emitter). A test set-up was developed and is described and a measurement methodology was determined for each of the two operations studied. The robustness of the experimental results is discussed and shows good tendencies. The impact of air-flow extraction rate was assessed and the pressure loss of the system for each machine established. For the circular saws, three machines over the nine tested could be classified in the low dust emitter group. Their mean concentration values measured are between 0.64 and 0.98 mg/m³ for the low dust emitter group and from 2.55 and 4.37 mg/m³ for the high dust emitter group. From concentration measurements, a machine classification is possible-one for sanding machines and one for sawing machines-and a ratio from 1-7 is obtained when comparing the results. This classification will be helpful when a choice of high performance power tools, in terms of dust emission, must be made by professionals.

Evaluation of waste isoflurane gas exposure during rodent surgery in an Australian university

Biomedical researchers use of inhalational anesthetics has increased in recent years. Use of isoflurane as an inhalational anesthetic may result in human exposure to waste anesthetic gas. Potential health effects from exposure include genotoxic and hepatotoxic effects with some evidence of teratogenic and reproductive effects. Research suggests that exposure to waste anesthetic gas within human hospital settings has improved substantially but exposures to biomedical researchers and veterinarians still requires improvement. A number of biomedical research facilities are located at The University of Queensland, Australia, where researchers and animal handlers are potentially exposed to waste isoflurane gas. There is limited published data on the exposures received by biomedical researchers performing routine procedures. This project aimed to assess isoflurane exposure received during routine rodent anesthetic protocols performed at the university. Atmospheric concentrations of isoflurane were assessed via two methods-personal active gas sampling using sorbent tubes and direct readings using infrared spectroscopy. Total procedure and isoflurane exposure times ranged from 135-268 min. Personal sorbent tube sampling detected isoflurane levels from below detectable limits (<0.01 ppm) to a Time Weighted Average for the task (TWA-Task) of 6.20 ppm (0.73 ± 9.13). Participants were not exposed to isoflurane outside of the sampling period during the remainder of the workday. TWA-8 hr adjusted levels ranged from below the limit of detection to 1.76 ppm isoflurane (0.69 ppm ± 0.61 ppm). The infrared spectroscopy readings taken in the breathing zone of participants ranged from 0.1-68 ppm. Results indicate that if adequately controlled through good room ventilation, effective active gas scavenging and well constructed anesthetic equipment, waste anesthetic exposures are minimal. However, where industry standards are not met exposures may occur, including some high peak exposures.

Influence of cigarette filter ventilation on smokers' mouth level exposure to tar and nicotine

Cigarette filter ventilation allows air to be drawn into the filter, diluting the cigarette smoke. Although machine smoking reveals that toxicant yields are reduced, it does not predict human yields. The objective of this study was to investigate the relationship between cigarette filter ventilation and mouth level exposure (MLE) to tar and nicotine in cigarette smokers. We collated and reviewed data from 11 studies across 9 countries, in studies performed between 2005 and 2013 which contained data on MLE from 156 products with filter ventilation between 0% and 87%. MLE among 7534 participants to tar and nicotine was estimated using the part-filter analysis method from spent filter tips. For each of the countries, MLE to tar and nicotine tended to decrease as filter ventilation increased. Across countries, per-cigarette MLE to tar and nicotine decreased as filter ventilation increased from 0% to 87%. Daily MLE to tar and nicotine also decreased across the range of increasing filter ventilation. These data suggest that on average smokers of highly ventilated cigarettes are exposed to lower amounts of nicotine and tar per cigarette and per day than smokers of cigarettes with lower levels of ventilation.

Integrated Management of Residential Indoor Air Quality: A Call for Stakeholders in a Changing Climate

A paradigm change in the management of environmental health issues has been observed in recent years: instead of managing specific risks individually, a holistic vision of environmental problems would assure sustainable solutions. However, concrete actions that could help translate these recommendations into interventions are lacking. This review presents the relevance of using an integrated indoor air quality management approach to ensure occupant health and comfort. At the nexus of three basic concepts (reducing contaminants at the source, improving ventilation, and, when relevant, purifying the indoor air), this approach can help maintain and improve indoor air quality and limit exposure to several contaminants. Its application is particularly relevant in a climate change context since the evolving outdoor conditions have to be taken into account during building construction and renovation. The measures presented through this approach target public health players, building managers, owners, occupants, and professionals involved in building design, construction, renovation, and maintenance. The findings of this review will help the various stakeholders initiate a strategic reflection on the importance of indoor air quality and climate change issues for existing and future buildings. Several new avenues and recommendations are presented to set the path for future research activities.

Randomized Trial of Interventions to Improve Childhood Asthma in Homes with Wood-burning Stoves

BACKGROUND

Household air pollution due to biomass combustion for residential heating adversely affects vulnerable populations. Randomized controlled trials to improve indoor air quality in homes of children with asthma are limited, and no such studies have been conducted in homes using wood for heating.

OBJECTIVES

Our aims were to test the hypothesis that household-level interventions, specifically improved-technology wood-burning appliances or air-filtration devices, would improve health measures, in particular Pediatric Asthma Quality of Life Questionnaire (PAQLQ) scores, relative to placebo, among children living with asthma in homes with wood-burning stoves.

METHODS

A three-arm placebo-controlled randomized trial was conducted in homes with wood-burning stoves among children with asthma. Multiple preintervention and postintervention data included PAQLQ (primary outcome), peak expiratory flow (PEF) monitoring, diurnal peak flow variability (dPFV, an indicator of airway hyperreactivity) and indoor particulate matter (PM) PM2.5.

RESULTS

Relative to placebo, neither the air filter nor the woodstove intervention showed improvement in quality-of-life measures. Among the secondary outcomes, dPFV showed a 4.1 percentage point decrease in variability [95% confidence interval (CI)=-7.8 to -0.4] for air-filtration use in comparison with placebo. The air-filter intervention showed a 67% (95% CI: 50% to 77%) reduction in indoor PM2.5, but no change was observed with the improved-technology woodstove intervention.

CONCLUSIONS

Among children with asthma and chronic exposure to woodsmoke, an air-filter intervention that improved indoor air quality did not affect quality-of-life measures. Intent-to-treat analysis did show an improvement in the secondary measure of dPFV.

TRIAL REGISTRATION

ClincialTrials.gov NCT00807183. https://doi.org/10.1289/EHP849.

Nano-metal oxides: Exposure and engineering control assessment

In January 2007, the National Institute for Occupational Safety and Health (NIOSH) conducted a field study to evaluate process specific emissions during the production of ENMs. This study was performed using the nanoparticle emission assessment technique (NEAT). During this study, it was determined that ENMs were released during production and cleaning of the process reactor. Airborne concentrations of silver, nickel, and iron were found both in the employee's personal breathing zone and area samples during reactor cleaning. At the completion of this initial survey, it was suggested that a flanged attachment be added to the local exhaust ventilation system.  NIOSH re-evaluated the facility in December 2011 to assess worker exposures following an increase in production rates. This study included a fully comprehensive emissions, exposure, and engineering control evaluation of the entire process. This study made use of the nanoparticle exposure assessment technique (NEAT 2.0). Data obtained from filter-based samples and direct reading instruments indicate that reactor cleanout increased the overall particle concentration in the immediate area. However, it does not appear that these concentrations affect areas outside of the production floor. As the distance between the reactor and the sample location increased, the observed particle number concentration decreased, creating a concentration gradient with respect to the reactor. The results of this study confirm that the flanged attachment on the local exhaust ventilation system served to decrease exposure potential.  Given the available toxicological data of the metals evaluated, caution is warranted. One should always keep in mind that occupational exposure levels were not developed specifically for nanoscale particles. With data suggesting that certain nanoparticles may be more toxic than the larger counterparts of the same material; employers should attempt to control emissions of these particles at the source, to limit the potential for exposure.

Dynamic interaction of a downward plane jet and a cough jet with respect to particle transmission: An analytical and experimental study

A cough jet can travel beyond the breathing zone of the source person, and thus, infectious viral- and bacterial-laden particles can be transported from the source person to others in close proximity. To reduce the interpersonal transmission of coughed particles, the objective of this study was to analytically and experimentally investigate the performance of downward plane jets with various discharge velocities. Chamber measurements were conducted to examine the interaction between a transient cough jet (discharge velocities of 12 m/sec and 16 m/sec) and a steady downward plane jet (discharge velocities from 1.0-8.5 m/sec) with respect to the transport of and human exposure to coughed particles. The results show that a relatively high-speed cough can easily penetrate a downward plane jet with a discharge velocity of less than 6 m/sec. A downward plane jet with a discharge velocity of 8.5 m/sec can bend the cough jet to a certain extent. In this study, momentum comparison of the cough jet and the downward plane jet shows that the value of personal exposure to coughed particles depends on the ratio of jet momentums. The results show that when the two momentums are equivalent or if the downward plane jet has a greater momentum, the cough jet is deflected downward and does not reach the breathing zone of the target thermal dummy. Using the ratio of the two momentums, it may be estimated whether the transmission of a cough jet can be controlled. A trajectory model was developed based on the ratio of the two momentums of a cough jet and a downward jet and was validated using the experimental data. In addition, the predicted trajectory of the cough jet agreed well with the results from smoke visualization experiments. This model can be used to guide the design of downward plane jet systems for protection of occupants from coughed particles.

Measured performance of filtration and ventilation systems for fine and ultrafine particles and ozone in an unoccupied modern California house

This study evaluated nine ventilation and filtration systems in an unoccupied 2006 house located 250 m downwind of the I-80 freeway in Sacramento, California. Systems were evaluated for reducing indoor concentrations of outdoor particles in summer and fall/winter, ozone in summer, and particles from stir-fry cooking. Air exchange rate was measured continuously. Energy use was estimated for year-round operation in California. Exhaust ventilation without enhanced filtration provided indoor PM_2.5 that was 70% lower than outdoors. Supply ventilation with MERV13 filtration provided slightly less protection, whereas supply MERV16 filtration reduced PM_2.5 by 97-98% relative to outdoors. Supply filtration systems used little energy but provided no benefits for indoor-generated particles. Systems with MERV13-16 filter in the recirculating heating and cooling unit (FAU) operating continuously or 20 min/h reduced PM_2.5 by 93-98%. Across all systems, removal percentages were higher for ultrafine particles and lower for black carbon, relative to PM_2.5 . Indoor ozone was 3-4% of outdoors for all systems except an electronic air cleaner that produced ozone. Filtration via the FAU or portable filtration units lowered PM_2.5 by 25-75% when operated over the hour following cooking. The energy for year-round operation of FAU filtration with an efficient blower motor was estimated at 600 kWh/year.

Inhalation exposure during spray application and subsequent sanding of a wood sealant containing zinc oxide nanoparticles

Nano-enabled construction products have entered into commerce. There are concerns about the safety of manufactured nanomaterials, and exposure assessments are needed for a more complete understanding of risk. This study assessed potential inhalation exposure to ZnO nanoparticles during spray application and power sanding of a commercially available wood sealant and evaluated the effectiveness of local exhaust ventilation in reducing exposure. A tradesperson performed the spraying and sanding inside an environmentally-controlled chamber. Dust control methods during sanding were compared. Filter-based sampling, electron microscopy, and real-time particle counters provided measures of exposure. Airborne nanoparticles above background levels were detected by particle counters for all exposure scenarios. Nanoparticle number concentrations and particle size distributions were similar for sanding of treated versus untreated wood. Very few unbound nanoparticles were detected in aerosol samples via electron microscopy, rather nano-sized ZnO was contained within, or on the surface of larger airborne particles. Whether the presence of nanoscale ZnO in these aerosols affects toxicity merits further investigation. Mass-based exposure measurements were below the NIOSH Recommended Exposure Limit for Zn, although there are no established exposure limits for nanoscale ZnO. Local exhaust ventilation was effective, reducing airborne nanoparticle number concentrations by up to 92% and reducing personal exposure to total dust by at least 80% in terms of mass. Given the discrepancies between the particle count data and electron microscopy observations, the chemical identity of the airborne nanoparticles detected by the particle counters remains uncertain. Prior studies attributed the main source of nanoparticle emissions during sanding to copper nanoparticles generated from electric sander motors. Potentially contrary results are presented suggesting the sander motor may not have been the primary source of nanoparticle emissions in this study. Further research is needed to understand potential risks faced by construction workers exposed to mixed aerosols containing manufactured nanomaterials. Until these risks are better understood, this study demonstrates that engineering controls can reduce exposure to manufactured nanomaterials; doing so may be prudent for protecting worker health.

Metal Exposures at three U.S. electronic scrap recycling facilities

Many metals found in electronic scrap are known to cause serious health effects, including but not limited to cancer and respiratory, neurologic, renal, and reproductive damage. The National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention performed three health hazard evaluations at electronic scrap recycling facilities in the U.S. to characterize employee exposure to metals and recommend control strategies to reduce these exposures. We performed air, surface, and biological monitoring for metals. We found one overexposure to lead and two overexposures to cadmium. We found metals on non-production surfaces, and the skin and clothing of workers before they left work in all of the facilities. We also found some elevated blood lead levels (above 10 micrograms per deciliter), however no employees at any facility had detectable mercury in their urine or exceeded 34% of the OELs for blood or urine cadmium. This article focuses on sampling results for lead, cadmium, mercury, and indium. We provided recommendations for improving local exhaust ventilation, reducing the recirculation of potentially contaminated air, using respirators until exposures are controlled, and reducing the migration of contaminants from production to non-production areas. We also recommended ways for employees to prevent taking home metal dust by using work uniforms laundered on-site, storing personal and work items in separate lockers, and using washing facilities equipped with lead-removing cleaning products.

An easy tool to assess ventilation in health facilities as part of air-borne transmission prevention: a cross-sectional survey from Uganda

BACKGROUND

No guidelines exist on assessing ventilation through air changes per hour (ACH) using a vaneometer. The objective of the study was to evaluate the position and frequency for measuring air velocity using a vaneometer to assess ventilation with ACH; and to assess influence of ambient temperature and weather on ACH.

METHODS

Cross-sectional survey in six urban health facilities in Kampala, Uganda. Measurements consisted of taking air velocity on nine separate moments in five positions in each opening of the TB clinic, laboratory, outpatient consultation and outpatient waiting room using a vaneometer. We assessed in addition the ventilation with the "20% rule", and compared this estimation with the ventilation in ACH assessed using the vaneometer.

RESULTS

A total of 189 measurements showed no influence on air velocity of the position and moment of the measurement. No significant influence existed of ambient temperature and a small but significant influence of sunny weather. Ventilation was adequate in 17/24 (71%) of all measurements. Using the "20% rule", ventilation was adequate in 50% of rooms assessed. Agreement between both methods existed in 13/23 (56%) of the rooms assessed.

CONCLUSION

Most rooms had adequate ventilation when assessed using a vaneometer for measuring air velocity. A single vaneometer measurement of air velocity is adequate to assess ventilation in this setting. These findings provide practical input for clear guidelines on assessing ventilation using a vaneometer. Assessing ventilation with a vaneometer differs substantially from applying the "20% rule".

Ventilation, indoor air quality, and health in homes undergoing weatherization

Ventilation standards, health, and indoor air quality have not been adequately examined for residential weatherization. This randomized trial showed how ASHRAE 62-1989 (n=39 houses) and ASHRAE 62.2-2010 (n=42 houses) influenced ventilation rates, moisture balance, indoor air quality, and self-reported physical and mental health outcomes. Average total airflow was nearly twice as high for ASHRAE 62.2-2010 (79 vs. 39 cfm). Volatile organic compounds, formaldehyde and carbon dioxide were all significantly reduced for the newer standard and first-floor radon was marginally lower, but for the older standard, only formaldehyde significantly decreased. Humidity in the ASHRAE 62.2-2010 group was only about half that of the ASHRAE 62-1989 group using the moisture balance metric. Radon was higher in the basement but lower on the first floor for ASHRAE 62.2-2010. Children in each group had fewer headaches, eczema, and skin allergies after weatherization and adults had improvements in psychological distress. Indoor air quality and health improve when weatherization is accompanied by an ASHRAE residential ventilation standard, and the 2010 ASHRAE standard has greater improvements in certain outcomes compared to the 1989 standard. Weatherization, home repair, and energy conservation projects should use the newer ASHRAE standard to improve indoor air quality and health.

The impact of particle filtration on indoor air quality in a classroom near a highway

A pilot study was performed to investigate whether the application of a new mechanical ventilation system with a fine F8 (MERV14) filter could improve indoor air quality in a high school near the Amsterdam ring road. PM10, PM2.5, and black carbon (BC) concentrations were measured continuously inside an occupied intervention classroom and outside the school during three sampling periods in the winter of 2013/2014. Initially, 3 weeks of baseline measurements were performed, with the existing ventilation system and normal ventilation habits. Next, an intervention study was performed. A new ventilation system was installed in the classroom, and measurements were performed during 8 school weeks, in alternating 2-week periods with and without the filter in the ventilation system under otherwise identical ventilation conditions. Indoor/outdoor ratios measured during the weeks with filter were compared with those measured without filter to evaluate the ability of the F8 filter to improve indoor air quality. During teaching hours, the filter reduced BC exposure by, on average, 36%. For PM10 and PM2.5, a reduction of 34% and 30% was found, respectively. This implies that application of a fine filter can reduce the exposure of schoolchildren to traffic exhaust at hot spot locations by about one-third.

Short-range airborne transmission of expiratory droplets between two people

The occurrence of close proximity infection for many respiratory diseases is often cited as evidence of large droplet and/or close contact transmission. We explored interpersonal exposure of exhaled droplets and droplet nuclei of two standing thermal manikins as affected by distance, humidity, ventilation, and breathing mode. Under the specific set of conditions studied, we found a substantial increase in airborne exposure to droplet nuclei exhaled by the source manikin when a susceptible manikin is within about 1.5 m of the source manikin, referred to as the proximity effect. The threshold distance of about 1.5 m distinguishes the two basic transmission processes of droplets and droplet nuclei, that is, short-range modes and the long-range airborne route. The short-range modes include both the conventional large droplet route and the newly defined short-range airborne transmission. We thus reveal that transmission occurring in close proximity to the source patient includes both droplet-borne (large droplet) and short-range airborne routes, in addition to the direct deposition of large droplets on other body surfaces. The mechanisms of the droplet-borne and short-range airborne routes are different; their effective control methods also differ. Neither the current droplet precautions nor dilution ventilation prevents short-range airborne transmission, so new control methods are needed.

Exhaust ventilation in attached garages improves residential indoor air quality

Previous research has shown that indoor benzene levels in homes with attached garages are higher than homes without attached garages. Exhaust ventilation in attached garages is one possible intervention to reduce these concentrations. To evaluate the effectiveness of this intervention, a randomized crossover study was conducted in 33 Ottawa homes in winter 2014. VOCs including benzene, toluene, ethylbenzene, and xylenes, nitrogen dioxide, carbon monoxide, and air exchange rates were measured over four 48-hour periods when a garage exhaust fan was turned on or off. A blower door test conducted in each garage was used to determine the required exhaust fan flow rate to provide a depressurization of 5 Pa in each garage relative to the home. When corrected for ambient concentrations, the fan decreased geometric mean indoor benzene concentrations from 1.04 to 0.40 μg/m³ , or by 62% (P<.05). The garage exhaust fan also significantly reduced outdoor-corrected geometric mean indoor concentrations of other pollutants, including toluene (53%), ethylbenzene (47%), m,p-xylene (45%), o-xylene (43%), and carbon monoxide (23%) (P<.05) while having no impact on the home air exchange rate. This study provides evidence that mechanical exhaust ventilation in attached garages can reduce indoor concentrations of pollutants originating from within attached garages.

Vocal Ergonomics in the Workplace: Heating, Ventilation, and Air-Conditioning Method Influences on Vocal Comfort and Function

PURPOSE

The purpose of this study was to examine the influence of the heating, ventilation, and air-conditioning method on voice function following a voicing task using ecologically valid offices, one with radiant HVAC and one with forced air.

METHOD

A total of 12 consented participants (6 women, 6 men) narrated a video in each of 4 environmental conditions in a within-between repeated-measures design. Acoustic data were collected with an ambulatory phonation monitor and perceived phonatory effort was determined following the voicing task. Data were analyzed using a within-between repeated-measures analysis of variance with significance set at α < .05.

RESULTS

Perceived phonatory effort did not differ between environments; however, a significant difference in vocal amplitude between 2 trials was identified for the male participants and physiologically significant differences in vocal amplitude were identified for male and female participants.

CONCLUSIONS

The findings suggest that perceived phonatory effort may not be a sensitive measure of vocal function differences following a voicing task in ecologically valid office spaces despite significant acoustic findings. Future research should address longer exposure to environmental differences combined with a longer voicing task within ecologically valid work spaces as well as the recruitment of participants who have particular vulnerability to environmental perturbations.

An analysis of the radioactive contamination due to radon in a granite processing plant and its decontamination by ventilation

This work focuses on studying concentration distribution of ²²²Rn radioisotope in a granite processing plant. Using Computational Fluid Dynamic Techniques (CFD), the exposure of the workers to radiation was assessed and, in order to minimise this exposure, different decontamination scenarios using ventilation were analysed. Natural ventilation showed not sufficient to maintain radon concentration below acceptable limits, so a forced ventilation was used instead. Position of the granite blocks also revealed as a determining factor in the radioactive level distribution. Thus, a correct layout of the stored material and an adequate ventilation system can guarantee free of exposure to radiation zones within the studied workshop. This leads to a drastic fall in the exposure of the workers and consequently minimises their risk of developing aggressive illness like lung cancer.

Retention efficacy and release of radioiodine in fume hoods

Procedures to determine the release of hazardous gaseous substances including radioactive iodine are covered by different norms such as the European standard EN 14175 and the German national standard DIN 25466. The detection of sulphur hexafluoride (SF₆) is required to comply with the prescribed methodology. The detection limit of this test is 4.5·10^-7 mol/m³ in exhaust air. This detection limit would represent a very high activity in the region of 0.27 TBq/m³ leading to an unacceptable risk. We therefore developed a test using a filter system, consisting of a combination of filters capable of separating various chemical forms of airborne radioiodine. Air samples were collected directly in front of the fume hood and in the laboratory beside two different fume hoods of a similar construction with a final activated carbon filter for retention of radioiodine. Particular attention was therefore paid to air samples taken after passage over the filters. Significant differences in the degree of retention of iodine were found between the two fume hoods investigated. In one test a malfunction of the fume hood was demonstrated. In this case 0.148 × 10^-3% of the total released activity per m³ air was found 1 cm in front of the hood sash. A remarkably high fraction of the activity released in the fume hood (1.3 × 10^-3%/m³ air) was measured after the activated carbon filter. In the ambient air, values of up to 8.6 × 10^-6% pro m³ laboratory air sampled were measured, despite a 6-8-fold air exchange. The selected procedure is a factor of 10¹¹ (Schomäcker et al., 2001) more sensitive than the standard recommended methods (EN 14175). The standard test prescribed by the DIN/EN failed to reveal any inadequacy in the protective function of the radionuclide hood with respect to radioiodine retention.

[Tilting at WIP windmills in the OR: laminar flow might be harmful]

The World Health Organization has published a new guideline for the prevention of surgical site infection (SSI), according to which laminar airflow systems should not be used to reduce the risk of SSI in the OR. The Dutch Health Care Inspectorate has, on the other hand, published a directive demanding laminar airflow in most operation rooms in Dutch hospitals. This directive is based on an evidence-based report from the Dutch Working Group on Infection Prevention (WIP). Since these guidelines are contradictory, the evidence presented in the WHO report as well as in the WIP report is evaluated in this article. The conclusion is that the WIP report used the available literature selectively, resulting in a favourable but false advantage for the laminar airflow system. The directive on laminar airflow should therefore be withdrawn and the WHO guideline should be implemented in Dutch hospitals.

Models for nearly every occasion: Part I - One box models

The standard "well mixed room," "one box" model cannot be used to predict occupational exposures whenever the scenario involves the use of local controls. New "constant emission" one box models are proposed that permit either local exhaust or local exhaust with filtered return, coupled with general room ventilation or the recirculation of a portion of the general room exhaust. New "two box" models are presented in Part II of this series. Both steady state and transient models were developed. The steady state equation for each model, including the standard one box steady state model, is augmented with an additional factor reflecting the fraction of time the substance was generated during each task. This addition allows the easy calculation of the average exposure for cyclic and irregular emission patterns, provided the starting and ending concentrations are zero or near zero, or the cumulative time across all tasks is long (e.g., several tasks to a full shift). The new models introduce additional variables, such as the efficiency of the local exhaust to immediately capture freshly generated contaminant and the filtration efficiency whenever filtered exhaust is returned to the workspace. Many of the model variables are knowable (e.g., room volume and ventilation rate). A structured procedure for calibrating a model to a work scenario is introduced that can be applied to both continuous and cyclic processes. The "calibration" procedure generates estimates of the generation rate and all of remaining unknown model variables.

Models for nearly every occasion: Part II - Two box models

The "well-mixed room" two box models are often used to predict near and far field concentrations for a specific task, but are limited to scenarios where local exhaust controls are not used. In Part II of this series, new two box models are presented that permit local controls that either exhaust to the outside or return filtered air to the workspace. Additional models are presented that also allow for the recirculation of a filtered portion of the general ventilation flowrate. During the concentration increase phase the emission rate is assumed to be relatively constant. Both steady state and transient equations were developed for each scenario. An additional factor, representing the fraction of time that the substance is being emitted during a task or set of tasks, was added to the standard and new steady state models. This simple modification permits the easy calculation of the average near and far field concentrations for cyclic and irregular emission patterns, provided the starting and ending concentrations are identical (e.g., zero or near zero) or the cumulative task time is long (e.g., two or more task cycles to a full shift, depending upon the number of room air changes per task). Additional variables are introduced with the new models, such as the efficiency of a local control to immediately capture freshly generated contaminant and the filtration efficiency whenever filtered exhaust is returned to the workspace. Many of the model variables are knowable (e.g., room volume and ventilation rate). Others can be approximated using manufacturer specifications or published values (e.g., filtration efficiency). A structured procedure for calibrating a model to a work scenario is presented that can be applied to both continuous and cyclic processes. The "calibration" procedure generates estimates of all of the unknown model variables, including the generation rate and the effective near field flowrate (which takes into account potentially complex near field air currents as well as any thermal plumes created by a hot process).

Evaluation and control of isoflurane during experimental dental procedures on rodents

The purpose of this study was to assess exposures to isoflurane to employees performing an experimental dental procedure on rodents. Isoflurane was used as an anesthetic for rodents during injections and placement of dental apparatus into the mouth. We collected eight full-shift samples using passive badges over a three-week period. The procedure was performed once a week for approximately 45 min each day. Results showed that employees were being exposed to isoflurane above the National Institute for Occupational Safety and Health recommended exposure level for halogenated anesthetic gases of two parts per million. The employer installed a ventilation system in the procedure room after the initial sampling and results. We collected 12 full-shift samples after the ventilation system was in place. Results showed an approximate 86% decrease in isoflurane concentration.

Relationships between indoor radon concentrations, thermal retrofit and dwelling characteristics

A monitoring campaign was conducted on a sample of more than 3400 dwellings in Brittany, France from 2011 to 2014. The measurements were collected using one passive dosimeter per dwelling over two months during the heating season, according to the NF ISO 11665-8 (2013) standard. Moreover, building characteristics such as the period of construction, construction material, type of foundation, and thermal retrofit were determined using a questionnaire. The final data set consisted of 3233 houses with the measurement results and the questionnaire answers. Multivariate linear regression models were applied to explore the relationships between the indoor radon concentrations and building characteristics, particularly the thermal retrofit. The geometric mean of the indoor radon concentration was 155 Bq m^-3 (with a geometric standard deviation of 3). The houses that had undergone a thermal retrofit had a higher average radon concentration than those that had not, which may have been due to a decrease in air permeability of the building envelope following rehabilitation work that did not systematically include proper management of the ventilation. Other building characteristics, primarily the building material and the foundation type, were associated with the indoor radon concentration. The indoor radon concentrations were higher in older houses built with granite or other stone, with a slab-on-grade foundation and without any ventilation system.

A comparison of control banding tools for nanomaterials

Control banding (CB) is a useful approach to evaluate and control the risk of exposure to nanomaterials (NM) due to uncertainty surrounding their toxicity and challenges associated with their measurement. Four CB tools specifically developed for NMs (NanoSafer, Stoffenmanager-Nano, NanoTool, and the Precautionary matrix) have been evaluated for their changes to differences in hazard and exposure input data. The hazard and exposure classification were also compared with experimental data. The tools provided different hazard and emission/exposure outputs when compared with each other and with experimental data. For some of the tools the information required to estimate the hazard is not always available in the Safety Data Sheet and it requires expert judgement. The tools have the potential to be valuable starting points to assess areas of high priority, although outputs should be interpreted with care. Further work should be done to improve their estimates, especially the inclusion of modifiers that account for the effectiveness of the ventilation and the effect of high temperatures during the process.

Effects of budesonide on the lung functions, inflammation and apoptosis in a saline-lavage model of acute lung injury

Diffuse alveolar injury, edema, and inflammation are fundamental signs of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Whereas the systemic administration of corticosteroids previously led to controversial results, this study evaluated if corticosteroids given intratracheally may improve lung functions and reduce edema formation, migration of cells into the lung and their activation in experimentally-induced ALI. In oxygen-ventilated rabbits, ALI was induced by repetitive saline lung lavage, until PaO2 decreased to < 26.7 kPa in FiO₂ 1.0. Then, one group of animals was treated with corticosteroid budesonide (Pulmicort susp inh, AstraZeneca; 0.25 mg/kg) given intratracheally by means of inpulsion regime of high-frequency jet ventilation, while another group was non-treated, and both groups were oxygen-ventilated for following 5 hours. Another group of animals served as healthy controls. After sacrifice of animals, left lung was saline-lavaged and protein content was measured and cells in the lavage fluid were determined microscopically. Right lung tissue was used for estimation of edema formation (expressed as wet/dry weight ratio), for histomorphological investigation, immunohistochemical determination of apoptosis of lung cells, and for determination of markers of inflammation and lung injury (IL-1β, IL-6, IL-8, TNF-α, IFNγ, esRAGE, caspase-3) by ELISA methods. Levels of several cytokines were estimated also in plasma. Repetitive lung lavage worsened gas exchange, induced lung injury, inflammation and lung edema and increased apoptosis of lung epithelial cells. Budesonide reduced lung edema, cell infiltration into the lung and apoptosis of epithelial cells and decreased concentrations of proinflammatory markers in the lung and blood. These changes resulted in improved ventilation. Concluding, curative intratracheal treatment with budesonide alleviated lung injury, inflammation, apoptosis of lung epithelial cells and lung edema and improved lung functions in a lavage model of ALI. These findings suggest a potential of therapy with inhaled budesonide also for patients with ARDS.

A Comparison between Temperature-Controlled Laminar Airflow Device and a Room Air-Cleaner in Reducing Exposure to Particles While Asleep

People spend approximately one third of their life sleeping. Exposure to pollutants in the sleep environment often leads to a variety of adverse health effects, such as development and exacerbation of asthma. Avoiding exposure to these pollutants by providing a sufficient air quality in the sleep environment might be a feasible method to alleviate these health symptoms. We performed full-scale laboratory measurements using a thermal manikin positioned on an experimental bed. Three ventilation settings were tested: with no filtration system operated, use of portable air cleaner and use of a temperature-controlled laminar airflow (TLA) device. The first part of the experiment investigated the air-flow characteristics in the breathing zone. In the second part, particle removal efficiency was estimated. Measured in the breathing zone, the room air cleaner demonstrated high turbulence intensity, high velocity and turbulence diffusivity level, with a particle reduction rate of 52% compared to baseline after 30 minutes. The TLA device delivered a laminar airflow to the breathing zone with a reduction rate of 99.5%. During a periodical duvet lifting mimicking a subject's movement in bed, the particle concentration was significantly lower with the TLA device compared to the room air cleaner. The TLA device provided a barrier which significantly reduced the introduction of airborne particles into the breathing zone. Further studies should be conducted for the understanding of the transport of resuspended particles between the duvet and the laying body.

Validation of Contamination Control in Rapid Transfer Port Chambers for Pharmaceutical Manufacturing Processes

There is worldwide concern with regard to the adverse effects of drug usage. However, contaminants can gain entry into a drug manufacturing process stream from several sources such as personnel, poor facility design, incoming ventilation air, machinery and other equipment for production, etc. In this validation study, we aimed to determine the impact and evaluate the contamination control in the preparation areas of the rapid transfer port (RTP) chamber during the pharmaceutical manufacturing processes. The RTP chamber is normally tested for airflow velocity, particle counts, pressure decay of leakage, and sterility. The air flow balance of the RTP chamber is affected by the airflow quantity and the height above the platform. It is relatively easy to evaluate the RTP chamber′s leakage by the pressure decay, where the system is charged with the air, closed, and the decay of pressure is measured by the time period. We conducted the determination of a vaporized H₂O₂ of a sufficient concentration to complete decontamination. The performance of the RTP chamber will improve safety and can be completely tested at an ISO Class 5 environment.

Potential impact of a ventilation intervention for influenza in the context of a dense indoor contact network in Hong Kong

Emerging diseases may spread rapidly through dense and large urban contact networks. We constructed a simple but novel dual-contact network model to account for both airborne contact and close contact of individuals in the densely populated city of Hong Kong. The model was then integrated with an existing epidemiological susceptible-exposed-infectious-recovered (SEIR) model, and we used a revised Wells-Riley model to estimate infection risks by the airborne route and an exponential dose-response model for risks by the contact and droplet routes. A potential outbreak of partially airborne influenza was examined, assuming different proportions of transmission through the airborne route. Our results show that building ventilation can have significant effects in airborne transmission-dominated conditions. Moreover, even when the airborne route only contributes 20% to the total infection risk, increasing the ventilation rate has a strong influence on transmission dynamics, and it also can achieve control effects similar to those of wearing masks for patients, isolation and vaccination.

Can changing the timing of outdoor air intake reduce indoor concentrations of traffic-related pollutants in schools?

Traffic emissions have been associated with a wide range of adverse health effects. Many schools are situated close to major roads, and as children spend much of their day in school, methods to reduce traffic-related air pollutant concentrations in the school environment are warranted. One promising method to reduce pollutant concentrations in schools is to alter the timing of the ventilation so that high ventilation time periods do not correspond to rush hour traffic. Health Canada, in collaboration with the Ottawa-Carleton District School Board, tested the effect of this action by collecting traffic-related air pollution data from four schools in Ottawa, Canada, during October and November 2013. A baseline and intervention period was assessed in each school. There were statistically significant (P < 0.05) reductions in concentrations of most of the pollutants measured at the two late-start (9 AM start) schools, after adjusting for outdoor concentrations and the absolute indoor-outdoor temperature difference. The intervention at the early-start (8 AM start) schools did not have significant reductions in pollutant concentrations. Based on these findings, changing the timing of the ventilation may be a cost-effective mechanism of reducing traffic-related pollutants in late-start schools located near major roads.

The MERMAID study: indoor and outdoor average pollutant concentrations in 10 low-energy school buildings in France

Indoor air quality was characterized in 10 recently built energy-efficient French schools during two periods of 4.5 days. Carbon dioxide time-resolved measurements during occupancy clearly highlight the key role of the ventilation rate (scheduled or occupancy indexed), especially in this type of building, which was tightly sealed and equipped with a dual-flow ventilation system to provide air refreshment. Volatile organic compounds (VOCs) and inorganic gases (ozone and NO2 ) were measured indoors and outdoors by passive techniques during the occupied and the unoccupied periods. Over 150 VOC species were identified. Among them, 27 species were selected for quantification, based on their occurrence. High concentrations were found for acetone, 2-butanone, formaldehyde, toluene, and hexaldehyde. However, these concentrations are lower than those previously observed in conventional school buildings. The indoor/outdoor and unoccupied/occupied ratios are informative regarding emission sources. Except for benzene, ozone, and NO2 , all the pollutants in these buildings have an indoor source. Occupancy is associated with increased levels of acetone, 2-butanone, pentanal, butyl acetate, and alkanes.

The effects of bedroom air quality on sleep and next-day performance

The effects of bedroom air quality on sleep and next-day performance were examined in two field-intervention experiments in single-occupancy student dormitory rooms. The occupants, half of them women, could adjust an electric heater to maintain thermal comfort but they experienced two bedroom ventilation conditions, each maintained for 1 week, in balanced order. In the initial pilot experiment (N = 14), bedroom ventilation was changed by opening a window (the resulting average CO2 level was 2585 or 660 ppm). In the second experiment (N = 16), an inaudible fan in the air intake vent was either disabled or operated whenever CO2 levels exceeded 900 ppm (the resulting average CO2 level was 2395 or 835 ppm). Bedroom air temperatures varied over a wide range but did not differ between ventilation conditions. Sleep was assessed from movement data recorded on wristwatch-type actigraphs and subjects reported their perceptions and their well-being each morning using online questionnaires. Two tests of next-day mental performance were applied. Objectively measured sleep quality and the perceived freshness of bedroom air improved significantly when the CO2 level was lower, as did next-day reported sleepiness and ability to concentrate and the subjects' performance of a test of logical thinking.

Sick Building Syndrome: What It Is and Tips for Prevention

Telltale clues include increased absenteeism, a large number of occupants complaining about vague but similar symptoms, and a common history of symptom resolution when people are not in the building.

San Francisco childcare centers' preparedness in the prevention and management of asthma among preschool-aged children

INTRODUCTION

Asthma is a common health condition for children in childcare. National recommendations for asthma in childcare exist. However, no studies have investigated the extent to which childcare centers adhere to these recommendations. We aimed to assess childcare center adherence to National Asthma Education and Prevention Program (NAEPP) recommendations for asthma care and preparedness and to identify characteristics associated with increased adherence to national asthma recommendations.

METHODS

We developed a standardized instrument. Each childcare center received a score of 0 through 7 based on number of recommendations met. We conducted t-tests, chi square tests and linear regression to identify childcare center factors associated with increased asthma preparedness.

RESULTS

36 out of 40 eligible childcare centers (90%) participated. These sites served 1570 children primarily between the ages of 2 to 5 years. On average, centers met 3.8 out of 7 (SD  =  1.3) recommendations. Staff familiarity caring for children with asthma (p < 0.001) and the center's asthma prevalence (p  =  0.01) was positively associated with the center's asthma preparedness. The 3 areas most in need of improvement related to asthma medications, asthma action plans and asthma policies. None of the managers reported being familiar with the NAEPP recommendations.

DISCUSSION

There is room for improvement in the asthma care and preparedness of childcare centers. The 3 areas in which centers performed poorly (appropriate asthma medication management, use of asthma action plans, and presence of appropriate asthma policies) suggest that closer collaboration between clinicians and childcare centers may be a key to improving asthma management for young children.

Classroom ventilation and indoor air quality-results from the FRESH intervention study

Inadequate ventilation of classrooms may lead to increased concentrations of pollutants generated indoors in schools. The FRESH study, on the effects of increased classroom ventilation on indoor air quality, was performed in 18 naturally ventilated classrooms of 17 primary schools in the Netherlands during the heating seasons of 2010-2012. In 12 classrooms, ventilation was increased to targeted CO2 concentrations of 800 or 1200 ppm, using a temporary CO2 controlled mechanical ventilation system. Six classrooms were included as controls. In each classroom, data on endotoxin, β(1,3)-glucans, and particles with diameters of <10 μm (PM10 ) and <2.5 μm (PM2.5 ) and nitrogen dioxide (NO2 ) were collected during three consecutive weeks. Associations between the intervention and these measured indoor air pollution levels were assessed using mixed models, with random classroom effects. The intervention lowered endotoxin and β(1,3)-glucan levels and PM10 concentrations significantly. PM10 for instance was reduced by 25 μg/m³ (95% confidence interval 13-38 μg/m³) from 54 μg/m³ at maximum ventilation rate. No significant differences were found between the two ventilation settings. Concentrations of PM2.5 and NO2 were not affected by the intervention. Our results provide evidence that increasing classroom ventilation is effective in decreasing the concentrations of some indoor-generated pollutants.

Chemical characterization of indoor and outdoor fine particulate matter in an occupied apartment in Rome, Italy

The daily concentration and chemical composition of PM2.5 was determined in indoor and outdoor 24-h samples simultaneously collected for a total of 5 weeks during a winter and a summer period in an apartment sited in Rome, Italy. The use of a specifically developed very quiet sampler (<35 dB) allowed the execution of the study while the family living in the apartment led its normal life. The indoor concentration of PM2.5 showed a small seasonal variation, while outdoor values were much higher during the winter study. Outdoor sources were found to contribute significantly to indoor PM concentration especially during the summer, when the apartment was naturally ventilated by opening the windows. During the winter the infiltration of outdoor PM components was lower and mostly regulated by the particle dimensions. Organics displayed In/Out ratios higher than unity during both periods; their indoor production increased significantly during the weekends, where the family stayed mostly at home. PM components were grouped into macrosources (soil, sea, secondary inorganics, traffic, organics). During the summer the main contributions to outdoor PM2.5 came from soil (30%), secondary inorganics (29%) and organics (22%). Organics dominated both indoor PM2.5 during the summer (60%) and outdoor and indoor PM2.5 during the winter (51% and 66%, respectively).

Indoor air quality in Portuguese schools: levels and sources of pollutants

Indoor air quality (IAQ) parameters in 73 primary classrooms in Porto were examined for the purpose of assessing levels of volatile organic compounds (VOCs), aldehydes, particulate matter, ventilation rates and bioaerosols within and between schools, and potential sources. Levels of VOCs, aldehydes, PM2.5 , PM10 , bacteria and fungi, carbon dioxide (CO2 ), carbon monoxide, temperature and relative humidity were measured indoors and outdoors and a walkthrough survey was performed concurrently. Ventilation rates were derived from CO2 and occupancy data. Concentrations of CO2 exceeding 1000 ppm were often encountered, indicating poor ventilation. Most VOCs had low concentrations (median of individual species <5 μg/m(3) ) and were below the respective WHO guidelines. Concentrations of particulate matter and culturable bacteria were frequently higher than guidelines/reference values. The variability of VOCs, aldehydes, bioaerosol concentrations, and CO2 levels between schools exceeded the variability within schools. These findings indicate that IAQ problems may persist in classrooms where pollutant sources exist and classrooms are poorly ventilated; source control strategies (related to building location, occupant behavior, maintenance/cleaning activities) are deemed to be the most reliable for the prevention of adverse health consequences in children in schools.

Do classroom ventilation rates in California elementary schools influence standardized test scores? Results from a prospective study

Limited evidence has associated lower ventilation rates (VRs) in schools with reduced student learning or achievement. We analyzed longitudinal data collected over two school years from 150 classrooms in 28 schools within three California school districts. We estimated daily classroom VRs from real-time indoor carbon dioxide measured by web-connected sensors. School districts provided individual-level scores on standard tests in Math and English, and classroom-level demographic data. Analyses assessing learning effects used two VR metrics: average VRs for 30 days prior to tests, and proportion of prior daily VRs above specified thresholds during the year. We estimated relationships between scores and VR metrics in multivariate models with generalized estimating equations. All school districts had median school-year VRs below the California VR standard. Most models showed some positive associations of VRs with test scores; however, estimates varied in magnitude and few 95% confidence intervals excluded the null. Combined-district models estimated statistically significant increases of 0.6 points (P = 0.01) on English tests for each 10% increase in prior 30-day VRs. Estimated increases in Math were of similar magnitude but not statistically significant. Findings suggest potential small positive associations between classroom VRs and learning.

Evaluation of thermal formation and air ventilation inside footwear during gait: The role of gait and fitting

Comfort is an important concept in footwear design. The microclimate inside footwear contributes to the perception of thermal comfort. To investigate the effect of ventilation on microclimate formation inside footwear, experiments with subjects were conducted at four gait speeds with three different footwear sizes. Skin temperature, metabolism, and body mass were measured at approximately 25 °C and 50% relative humidity, with no solar radiation and a calm wind. The footwear occupancy and ventilation rate were also estimated, with the latter determined using the tracer gas method. The experimental results revealed that foot movement, metabolism, evaporation, radiation, convection, and ventilation were the main factors influencing the energy balance for temperature formation on the surface of the foot. The cooling effect of ventilation on the arch temperature was observed during gait. The significance of the amount of air space and ventilation on the improvement in the thermal comfort of footwear was clarified.

The effect of increased classroom ventilation rate indicated by reduced CO2 concentration on the performance of schoolwork by children

The article reports on an experiment which investigated the effect of increased classroom ventilation rate on the performance of children aged 10-12 years. The experiment was executed at two different schools (two classrooms at each school) as a double-blind 2 × 2 crossover intervention where four different performance tests were used as surrogates for short-term concentration and logical thinking. Only complete pairs of test responses were included in the within-subject comparisons of performance, and data were not corrected for learning and fatigue effects. Analysis of the total sample suggested the number of correct answers was improved significantly in four of four performance test, addition (6.3%), number comparison (4.8%), grammatical reasoning (3.2%), and reading and comprehension (7.4%), when the outdoor air supply rate was increased from an average of 1.7 (1.4-2.0) to 6.6 l/s per person. The increased outdoor air supply rate did not have any significant effect on the number of errors in any of the performance tests. Results from questionnaires regarding pupil perception of the indoor environment, reported Sick Building Syndrome symptoms, and motivation suggested that the study classroom air was perceived more still and pupil were experiencing less pain in the eyes in the recirculation condition compared to the fresh air condition.

Assessment of ventilation and indoor air pollutants in nursery and elementary schools in France

The aim of this study was to characterize the relationship between Indoor Air Quality (IAQ) and ventilation in French classrooms. Various parameters were measured over one school week, including volatile organic compounds, aldehydes, particulate matter (PM2.5 mass concentration and number concentration), carbon dioxide (CO2 ), air temperature, and relative humidity in 51 classrooms at 17 schools. The ventilation was characterized by several indicators, such as the air exchange rate, ventilation rate (VR), and air stuffiness index (ICONE), that are linked to indoor CO2 concentration. The influences of the season (heating or non-heating), type of school (nursery or elementary), and ventilation on the IAQ were studied. Based on the minimum value of 4.2 l/s per person required by the French legislation for mechanically ventilated classrooms, 91% of the classrooms had insufficient ventilation. The VR was significantly higher in mechanically ventilated classrooms compared with naturally ventilated rooms. The correlations between IAQ and ventilation vary according to the location of the primary source of each pollutant (outdoor vs. indoor), and for an indoor source, whether it is associated with occupant activity or continuous emission.

Prediction of the Chemoreflex Gain by Common Clinical Variables in Heart Failure

BACKGROUND

Peripheral and central chemoreflex sensitivity, assessed by the hypoxic or hypercapnic ventilatory response (HVR and HCVR, respectively), is enhanced in heart failure (HF) patients, is involved in the pathophysiology of the disease, and is under investigation as a potential therapeutic target. Chemoreflex sensitivity assessment is however demanding and, therefore, not easily applicable in the clinical setting. We aimed at evaluating whether common clinical variables, broadly obtained by routine clinical and instrumental evaluation, could predict increased HVR and HCVR.

METHODS AND RESULTS

191 patients with systolic HF (left ventricular ejection fraction--LVEF--<50%) underwent chemoreflex assessment by rebreathing technique to assess HVR and HCVR. All patients underwent clinical and neurohormonal evaluation, comprising: echocardiogram, cardiopulmonary exercise test (CPET), daytime cardiorespiratory monitoring for breathing pattern evaluation. Regarding HVR, multivariate penalized logistic regression, Bayesian Model Averaging (BMA) logistic regression and random forest analysis identified, as predictors, the presence of periodic breathing and increased slope of the relation between ventilation and carbon dioxide production (VE/VCO2) during exercise. Again, the above-mentioned statistical tools identified as HCVR predictors plasma levels of N-terminal fragment of proBNP and VE/VCO2 slope.

CONCLUSIONS

In HF patients, the simple assessment of breathing pattern, alongside with ventilatory efficiency during exercise and natriuretic peptides levels identifies a subset of patients presenting with increased chemoreflex sensitivity to either hypoxia or hypercapnia.

Carbon Dioxide Detection and Indoor Air Quality Control

When building ventilation is reduced, energy is saved because it is not necessary to heat or cool as much outside air. Reduced ventilation can result in higher levels of carbon dioxide, which may cause building occupants to experience symptoms. Heating or cooling for ventilation air can be enhanced by a DCV system, which can save energy while providing a comfortable environment. Carbon dioxide concentrations within a building are often used to indicate whether adequate fresh air is being supplied to the building. These DCV systems use carbon dioxide sensors in each space or in the return air and adjust the ventilation based on carbon dioxide concentration; the higher the concentration, the more people occupy the space relative to the ventilation rate. With a carbon dioxide sensor DCV system, the fresh air ventilation rate varies based on the number ofpeople in the space, saving energy while maintaining a safe and comfortable environment.

Primary and secondary consequences of indoor air cleaners

Air cleaning is broadly applied to reduce contaminant concentrations in many buildings. Although diverse in underlying technology, mode of application, target contaminants, and effectiveness, there are also commonalities in the framework for understanding their primary impact (i.e. concentration reductions) and secondary impacts (e.g. energy use and by-product production). Furthermore, both primary and secondary impacts are moderated by the specific indoor context in which an air cleaner is used. This investigation explores the dynamics of removal efficiency in a variety of air cleaners and combines efficiency and flow rate to put air cleaning in the context of real indoor environments. This allows for the direct comparison to other indoor pollutant loss mechanisms (ventilation and deposition) and further suggests that effective air cleaner use is context and contaminant specific. The concentration reduction impacts of air cleaning need to be contrasted with the secondary consequences that arise from the use of air cleaners. This study emphasizes two important secondary consequences: energy use of the air cleaning process and primary and secondary emissions from air cleaners. This study also identifies current research challenges and areas for large leaps in our understanding of the role of air cleaners in improving indoor environmental quality.

Advanced air distribution: improving health and comfort while reducing energy use

Indoor environment affects the health, comfort, and performance of building occupants. The energy used for heating, cooling, ventilating, and air conditioning of buildings is substantial. Ventilation based on total volume air distribution in spaces is not always an efficient way to provide high-quality indoor environments at the same time as low-energy consumption. Advanced air distribution, designed to supply clean air where, when, and as much as needed, makes it possible to efficiently achieve thermal comfort, control exposure to contaminants, provide high-quality air for breathing and minimizing the risk of airborne cross-infection while reducing energy use. This study justifies the need for improving the present air distribution design in occupied spaces, and in general the need for a paradigm shift from the design of collective environments to the design of individually controlled environments. The focus is on advanced air distribution in spaces, its guiding principles and its advantages and disadvantages. Examples of advanced air distribution solutions in spaces for different use, such as offices, hospital rooms, vehicle compartments, are presented. The potential of advanced air distribution, and individually controlled macro-environment in general, for achieving shared values, that is, improved health, comfort, and performance, energy saving, reduction of healthcare costs and improved well-being is demonstrated. Performance criteria are defined and further research in the field is outlined.