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Indoor Air

Bonnie N Young, Maggie L Clark, Sarah Rajkumar, Megan L Benka-Coker, Annette Bachand, Robert D Brook, Tracy L Nelson, John Volckens, Steve Reynolds, Christian L'Orange, Nicholas Good, Kirsten Koehler, Sebastian Africano, Anibal B Osorto Pinel, Jennifer L Peel
Growing evidence links household air pollution exposure from biomass cookstoves with elevated blood pressure. We assessed cross-sectional associations of 24-hour mean concentrations of personal and kitchen fine particulate matter (PM2.5 ), black carbon (BC), and stove type with blood pressure, adjusting for confounders, among 147 women using traditional or cleaner-burning Justa stoves in Honduras. We investigated effect modification by age and body mass index. Traditional stove users had mean (standard deviation) personal and kitchen 24-hour PM2...
September 8, 2018: Indoor Air
Jennifer Therkorn, David Drewry, Thomas Pilholski, Kathryn Shaw-Saliba, Gregory Bova, Lisa L Maragakis, Brian Garibaldi, Lauren Sauer
Biocontainment units (BCUs) are facilities used to care for patients with highly infectious diseases. However, there is limited guidance on BCU protocols and design. This study presents the first investigation of how HVAC (heating, ventilation, air conditioning) operating conditions influence the dissemination of fluorescent tracer particles released in a BCU. Test conditions included normal HVAC operation and exhaust failure resulting in loss of negative pressure. A suspension of optical brightener powder and water was nebulized to produce fluorescent particles simulating droplet nuclei (0...
September 7, 2018: Indoor Air
Nan Zhang, Yuguo Li, Hong Huang
Fomites transmit infection. A key question is how surface contamination in a building is spread by human touch. Using video cameras, we collected more than 120,000 touch actions from 60 hours of high-resolution data on surface touch across five typical weekdays in a graduate student office. The students touched surfaces with one or both hands during 94.6% of the observed period. On average, each student made five touches per minute, with an average duration of 22 seconds per touch. High-touch and high-risk surfaces and people were identified...
September 4, 2018: Indoor Air
Yi Yang, Huihui Zhang, Sunday Segbenu Nunayon, Vincent Chan, Alvin C K Lai
A full-scale ventilation duct ultraviolet germicidal irradiation (in-duct UVGI) system was designed to investigate its disinfection efficacy on five airborne pathogens: Serratia marcescens, Pseudomonas alcaligenes, Escherichia coli, Salmonella enterica, and Staphylococcus epidermidis, with airflow Reynolds numbers from 4 × 104 to 8 × 104 . By varying the UV intensity, the susceptibility constants (Z-values) of the bacteria were experimentally determined to be 1.2, 1.0, 0.60, 0.39, and 0.37 m2 /J for S. marcescens, P...
September 1, 2018: Indoor Air
Yangyang Xie, Bin Zhao
Changes in the chemical constitution and sources of ambient PM2.5 following the infiltration of air into indoor environments were investigated. We collected PM2.5 samples from air inside and outside 31 rooms in Beijing residences during hazy episodes. We calculated the indoor-to-outdoor ratios and the correction (ki ) of each infiltration factor for each chemical component of PM2.5 to determine the effects of infiltrative behavior. The outdoor and indoor mass concentrations of PM2.5 during the sampling period were 70-460 and 10-315 μg/m3 , respectively...
August 28, 2018: Indoor Air
Jennie Cox, Kelechi Isiugo, Patrick Ryan, Sergey A Grinshpun, Michael Yermakov, Colleen Desmond, Roman Jandarov, Stephen Vesper, James Ross, Steven Chillrud, Karen Dannemiller, Tiina Reponen
Outdoor traffic-related airborne particles can infiltrate a building and adversely affect the indoor air quality. Limited information is available on the effectiveness of high-efficiency particulate air (HEPA) filtration of traffic-related particles. Here we investigated the effectiveness of portable HEPA air cleaners in reducing indoor concentrations of traffic-related and other aerosols, including black carbon (BC), PM2.5 , ultraviolet absorbing particulate matter (UVPM) (a marker of tobacco smoke), and fungal spores...
August 22, 2018: Indoor Air
Jose Ali Porras-Salazar, David P Wyon, Beatriz Piderit-Moreno, Sergio Contreras-Espinoza, Pawel Wargocki
A two-week-long intervention study was performed in two classrooms in an elementary school in Costa Rica. Split-cooling air-conditioning (AC) units were installed in both classrooms. During the first week, the air temperature was reduced in one classroom while in the other (placebo) classroom the fans were operated but no cooling was provided. During the second week, the conditions were exchanged to create a 2 × 2 crossover design in which each pupil was their own control. A total of 37 children performed tasks similar to school work and completed questionnaires reporting their thermal sensation and perceptions...
August 17, 2018: Indoor Air
Marije Te Kulve, Luc Schlangen, Wouter van Marken Lichtenbelt
Expanding the acceptable range of indoor temperatures allows to reduce building energy consumption and may be beneficial for health. Therefore, we explored whether light conditions can be used to influence thermal perception under various ambient temperatures. In two laboratory experiments, we tested the effect of the correlated color temperature of light (2700 K and 5800 K) and its intensity (5 and 1200 lux) on thermal perception. The light exposures were provided during cool, neutral, and warm thermal conditions...
August 16, 2018: Indoor Air
Aleksandr B Stefaniak, Lauren N Bowers, Alycia K Knepp, M Abbas Virji, Eileen M Birch, Jason E Ham, J R Wells, Chaolong Qi, Diane Schwegler-Berry, Sherri Friend, Alyson R Johnson, Stephen B Martin, Yong Qian, Ryan F LeBouf, Quinn Birch, Duane Hammond
Fused deposition modeling (FDM™) 3-dimensional printing uses polymer filament to build objects. Some polymer filaments are formulated with additives, though it is unknown if they are released during printing. Three commercially available filaments that contained carbon nanotubes (CNTs) were printed with a desktop FDM™ 3-D printer in a chamber while monitoring total particle number concentration and size distribution. Airborne particles were collected on filters and analyzed using electron microscopy. Carbonyl compounds were identified by mass spectrometry...
August 13, 2018: Indoor Air
Kelsey R Bilsback, Sarah R Eilenberg, Nicholas Good, Lauren Heck, Michael Johnson, John K Kodros, Eric M Lipsky, Christian L'Orange, Jeffrey R Pierce, Allen L Robinson, R Subramanian, Jessica Tryner, Ander Wilson, John Volckens
Emissions from solid-fuel cookstoves have been linked to indoor and outdoor air pollution, climate forcing, and human disease. Although task-based laboratory protocols, such as the Water Boiling Test (WBT), overestimate the ability of improved stoves to lower emissions, WBT emissions data are commonly used to benchmark cookstove performance, estimate indoor and outdoor air pollution concentrations, estimate impacts of stove intervention projects, and select stoves for large-scale control trials. Multiple-firepower testing has been proposed as an alternative to the WBT and is the basis for a new standardized protocol (ISO 19867-1:2018); however, data are needed to assess the value of this approach...
August 11, 2018: Indoor Air
Marianne F Touchie, Jeffrey A Siegel
In North America, the majority of homes use forced-air systems for heating and cooling. The proportion of time these systems operate, or runtime, has a significant impact on many building performance parameters. The recent adoption of smart thermostats in many North American homes presents a potential data source for runtime. Smart thermostat data collected from over 7000 homes were compared with nine other investigations and a runtime estimation method based on exterior temperature. The smart thermostat runtimes have a median of 18% across all homes, but show considerable variation between homes, even at constant exterior temperature conditions suggesting that factors besides climate (eg, system sizing, user operation) have a significant impact on runtime...
August 11, 2018: Indoor Air
Małgorzata Gołofit-Szymczak, Rafał L Górny
Proper hygienic conditions in office buildings are of a high importance for both health and well-being of the employees. The aim of this study was the direct comparison of different ventilation systems on microbiological environments in 15 office buildings. The results showed that both bacterial and fungal concentrations in the naturally ventilated office buildings were between 70 and 1600 cfu/m3 , while in the offices equipped with air-conditioning and mechanical ventilation systems, concentrations were lower, that is, between 10 and 530 cfu/m3 and 20 and 410 cfu/m3 , respectively...
July 30, 2018: Indoor Air
Malak Rizk, Fangfang Guo, Marie Verriele, Michael Ward, Sebastien Dusanter, Nadège Blond, Nadine Locoge, Coralie Schoemaecker
The assessment of VOC emission rates and sorption coefficients was performed for ten surfaces present within a classroom, using field and laboratory emission cells (FLEC) coupled to online and off-line VOC quantification techniques. A total of 21 identified VOCs were emitted by the different surfaces. VOC emission rates measured using PTR-ToF-MS were compared to gas chromatographic measurements. The results showed that the two methods are complementary to one another. Sorption parameters were also successfully measured for a mixture of 14 VOCs within a few hours (<17 hours per surface)...
July 19, 2018: Indoor Air
Twan van Hooff, Peter V Nielsen, Yuguo Li
The use of computational fluid dynamics (CFD) to solve indoor airflow problems has increased tremendously in the last decades. However, the accuracy of CFD simulations depends greatly on user experience, the available validation data, and the effort made to verify solutions. This study presents the results of a conference workshop, which assessed user influence on the CFD results obtained for a generic non-isothermal flow problem; ie, a backward-facing step flow problem with a heated wall below the supply. Fifty-five simulation sets were submitted by 32 teams...
July 12, 2018: Indoor Air
Janine Wolf, Knut Berlin, Ludwig Fembacher, Dieter Heitmann, Wolfgang Matzen, Lutz Nitschke, Marina Sysoltseva, Hermann Fromme
Indoor go-kart driving and viewing is enjoyed by people of all ages. However, it may pose health hazards, especially for children, pregnant women, cardiovascular patients, and elderly individuals. Depending on the race length, for example, high concentrations of various contaminants may result in severe health problems. Therefore, this project investigated the Indoor Air Quality of eight indoor go-kart facilities. In general, karts that used regular fuel produced the highest concentrations of CO, benzene, TVOC, and BaP, with maximum levels up to 150 mg/m3 , 170 μg/m3 , 2690 μg/m3 , and 8...
July 10, 2018: Indoor Air
Young J Son, Chungyoon Chun
Thermal pleasure is currently measured along psychological and physiological variables. However, in transient environments where temperatures change, it is hard to correlate psychological and physiological measures, because there is a delay in physiological changes. This study tests a method for correlating both measures using electroencephalogram (EEG), which can capture physiological feedback with a rapid response rate. In this experimental study, thermal pleasure was induced in a temperature step-change environment, one of non-uniform and transient environments...
July 10, 2018: Indoor Air
Qing Cao, Chun Chen, Sumei Liu, Chao-Hsin Lin, Daniel Wei, Qingyan Chen
Enhanced soiling on the surfaces around air supply nozzles due to particle deposition is frequently observed in commercial airliners. The problem is worsened by severe outdoor air pollution and flight delays in China. The particles in an aircraft cabin originate from both outdoor and in-cabin sources. This study conducted measurements on multiple commercial flights to obtain particle emission rates from in-cabin sources. Additional experiments on a retired MD-82 airplane provided justification of the in-flight measurements...
July 6, 2018: Indoor Air
David P Wyon, Jonathan E Ridenour
A field-intervention study was carried out in 106 households in Sweden. Without informing the householders, a retrofitted heat pump controller was twice disabled for 1 week at a time over a 4-week period during the heating season, using a single-blind cross-over design with two pseudorandomly selected groups of householders, each experiencing different conditions at any given time. Thermal comfort was assessed by observing the total number of times that householders made adjustments to their set point temperature under each condition...
July 6, 2018: Indoor Air
Xian Li, Tengfei Zhang, Shugang Wang
Detachment of fungal spores from moldy surfaces and the subsequent aerosolization can lead to adverse health effects. Spore aerosolization occurs when the forces for aerosolization exceed the binding forces of spores with their colonies. The threshold force to detach a spore from a growing colony remains unknown. This investigation measured the detachment of spores of Aspergillus niger from a colony using an atomic force microscope (AFM). The spores were first affixed to the cantilever of the AFM with ultraviolet curing glue, and then, the colony was moved downward until the spores detached...
June 26, 2018: Indoor Air
Chun-Chieh Tseng, Pei-Ying Yu, Je-Wen Liou, Kai-Chih Chang
The accurate quantification of antibiotic-resistant bacteria in indoor air has recently attracted increasing attention. Here, we investigated whether the susceptibility of a nosocomial infection-related microbe, Acinetobacter baumannii, to strong sampling stress caused by Nuclepore filter changes as it develops resistance to a drug called colistin. Both colistin-sensitive A. baumannii (CSAB) and colistin-resistant A. baumannii (CRAB) are generally desiccation-resistant strains that can be collected by filter sampling...
June 26, 2018: Indoor Air
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