Ambient Indoor Air Research Articles

Implementation of a botanical bioscrubber for the treatment of indoor ambient air

This study explores the effectiveness of a botanical bioscrubber system using Golden Pothos (Epipremnum aureum) in hydroponic setups to mitigate common indoor atmospheric pollutants. Over a 100-day operation, levels of SO2, NO2, O3, TVOC, CO, CO2, PM10, and PM2.5 were monitored, with a significant reduction in carbon-based compounds and particulate matter-. Notably, CO2 and PM2.5 removal efficiencies were significantly correlated with the foliar area, suggesting that the interaction between pollutants and plant leaves plays a crucial role in the phytoremediation process. In contrast, CO, PM10, and TVOC exhibited varied removal efficiencies, hinting the involvement of mechanisms beyond leaf interaction, such as adsorption in irrigation water or root system capture. The absence of significant correlations for PM10 emphasized the need for further investigation into alternative removal processes, potentially mediated by the root system. Overall, our findings suggest that botanical bioscrubbers, particularly those utilizing Golden Pothos, hold promise for indoor air purification through plant-based systems.

COVID-19 Mitigation in a K-12 School Setting: A Case Study of Avenues: The World School in New York City.

In this case study, we describe a well-resourced private school in New York City that implemented COVID-19 mitigation measures based on public health expert guidance and the lessons learned from this process. Avenues opened in New York City in 2012 and has since expanded, becoming Avenues: The World School, with campuses in São Paulo, Brazil; Shenzhen, China; the Silicon Valley, California; and online. It offers education at 16 grade levels: 2 early learning years, followed by a prekindergarten through grade 12. We describe the mitigation measures that Avenues implemented on its New York campus. We compare COVID-19 case prevalence at the school with COVID-19 case positivity in New York City, as reported by the New York State Department of Health. We also compare the school's indoor air quality to ambient indoor air quality measures reported in the literature. The school's mitigation measures successfully reduced the prevalence of COVID-19 among its students, staff, and faculty. The school also established a consistently high level of indoor air quality safety through various ventilation mechanisms, designed to reduce common indoor air pollutants. The school received positive parent and community feedback on the policies and procedures it established, with many parents commenting on the high level of trust and quality of communication established by the school. The successful reopening provides useful data for school closure and reopening standards to prepare for future pandemic and epidemic events.

Shape optimization of the energy efficiency of building retrofitted facade

The current state of research indicates a necessity of further examination in both numerical and experimental studies related to optimizing shapes of building enclosures for the enhancement of their energy efficiency. The demand for research primarily arises due to the numerical complexities associated with optimizing shapes for this specific purpose. Consequently, the primary objective of this article is to address and bridge these gaps in the field. To achieve this, a two-dimensional steady-state heat diffusion model is assumed to represent the physical processes occurring within building facades of varying shapes. A third type boundary condition is applied to the exterior boundary, encompassing convective and incident short-wave solar radiation effects. The calculation of short-wave radiation accounts for factors such as sunlight exposure and shading, influenced by the surrounding urban environment. The internal boundary interfaces with the indoor ambient air, and thus, a Robin boundary condition is adopted. To tackle the computational demands while ensuring accuracy, the boundary element method (BEM) is employed by discretizing the domain boundary into discrete elements. Then, two heat transfer design objectives are define according to the period of investigations: ones related to enhancing heat transfer and ones focused on thermal insulation problem. Last, a real-world case study is conducted, considering a house wall under varying climate conditions throughout the year. Optimal shapes for the external wall boundary are determined with the constraint that the optimized facade utilizes the same amount of material as the reference flat one. The results demonstrate a substantial increase in energy efficiency compared to the reference flat wall case.

Exploring microbial diversity during the artisanal Salchichón production: Food safety in the consumer spotlight

A study was conducted to evaluate the microbiological quality, safety, and variability along the production chain of two artisanal salchichón factories in Andalusia. Aerobic mesophilic bacteria (AMB), total coliforms, coagulase-positive Staphylococcus spp. (CPS), lactic-acid bacteria, moulds and yeasts and the presence of bacterial pathogens were investigated in 3 batches of raw materials, finished products, food-contact surfaces (FCS) and indoor ambient air by using classical microbiological and PCR/PFGE techniques. Of the 171 samples analysed, high inter-batch variability in microbial loads was observed. The prevalence of Listeria monocytogenes and Staphylococcus aureus in samples was 7.01% and 4.67%, respectively. Raw meat and FCS were identified as the potential sources of contamination of the finished products, with 16.67% testing positive for L. monocytogenes and 10% for S. aureus. Diverse sources of L. monocytogenes and a wide range of high pulsotypes were identified in the smaller producer. Although the largest producer showed better hygiene control, L. monocytogenes was detected in salchichón samples with growth-supporting physicochemical values. Therefore, the implementation of food safety management systems, hygiene measures for raw materials and monitoring of hazards are encouraged. Finally, the findings of this study offer valuable and current empirical data that can be used in risk assessments.

Diacetyl - A Critical Safety Review of the Science Defining the Environmental Inhalation Hazards Association with Chronic Lung Disease

In the last two decades scrutiny of several retrospective occupational studies on performed by NIOSH in the early 2000’s on ambient indoor air exposures to the flavoring chemical diacetyl and more complex butter flavoring formulations has led to a reported association between diacetyl and severe irreversible lung disease, primarily bronchiolitis obliterans. A group of laboratory rodent studies, performed primarily by associated researchers, followed in the next two decades with the intent to determine a plausible physiological mechanism for bronchiole scarring applicable to the human respiratory tract. Recently, a renewed interest in diacetyl as a flavoring constituent of vaping liquids and marijuana and inhalation exposures has emerged. This paper reviews the universe of published literature to date in relation to whether diacetyl or butter flavors containing diacetyl causes occupational or environmental lung disease, more specifically BO (i.e., general causation) and whether specific levels of inhaled diacetyl or butter flavors containing diacetyl are associated with chronic lung disease.
 The review included numerous journal articles, government reports, etc. Based upon the evidence, while the literature reflects a statistical association between both diacetyl and butter flavoring diacetyl mixtures and lung disease, there is sufficient evidence to conclude that general causation between exposure to diacetyl concentrations measured in the ambient air environments studied to date and chronic lung disease does not exist.

Physicochemical Assessment of Ambient Indoor Air Quality of a Tertiary Health Care Institution in South-Eastern Nigeria

Physicochemical Assessment of Ambient Indoor Air Quality of a Tertiary Health Care Institution in South-Eastern Nigeria

Effect of air filtration on house dust mite, cat and dog allergens and particulate matter in homes.

BackgroundIndoor allergens (i.e. from mite, cat and dog) are carried by airborne particulate matter. Thus, removal of particles would reduce allergen exposure. This work aims to assess the performance of air filtration on particulate matter and thus allergen removal in 22 bedrooms.MethodsIndoor air was sampled (with and without air filtration) with a cascade impactor and allergens were measured using enzyme‐linked immunosorbent assay (ELISA). Particulate matter (including ultrafine particles) was also monitored.ResultsThe median of allergen reduction was 75.2% for Der f 1 (p < 0.001, n = 20), 65.5% for Der p 1 (p = 0.066, n = 4), 76.6% for Fel d 1 (p < 0.01, n = 21) and 89.3% for Can f 1 (p < 0.01, n = 10). For size fractions, reductions were statistically significant for Der f 1 (all p < 0.001), Can f 1 (PM>10 and PM2.5–10, p < 0.01) and Fel d 1 (PM2.5–10, p < 0.01), but not for Der p 1 (all p > 0.05). PM was reduced in all fractions (p < 0.001). The allergens were found in all particle size fractions, higher mite allergens in the PM>10 and for pet allergens in the PM2.5–10.ConclusionsAir filtration was effective in removing mites, cat and dog allergens and also particulate matter from ambient indoor air, offering a fast and simple solution to mitigate allergen exposome.

Inhalation of VOCs from facial moisturizers and the influence of dose proximity.

Volatile organic compound (VOC) emissions from personal care products (PCPs) contribute to poor indoor air quality. Exposure to indoor VOCs is typically determined through ambient concentration measurements; however, for some PCPs the proximity of use to the nose and mouth may lead to disproportionately large inhaled doses. In this paper, we quantify emission factors for six common PCP ingredient VOCs (ethanol, 2-propanol, benzyl alcohol, 1,3-butanediol, t-butyl alcohol, and the grouping of monoterpenes as limonene) from 16 facial day-moisturizers using headspace analysis and selected ion flow-tube mass spectrometry. A wide range of emissions rates were observed across the range of products tested (e.g., ethanol 3.3-6.9×102 µg s-1 g[product]-1 , limonene 1.3×10-1 -4.1×10-1 µgs-1 g[product]-1 ). We use a mannequin head with reconstructed nose and mouth airways to sample VOCs from facial application at typical respiration volumes. A single facial application of moisturizer can lead to a much larger inhaled VOC dose than would be inhaled from typical indoor ambient air over 24h (e.g., limonene up to ~×16greater via facial application, ethanol up to ~×300). Emissions from facially applied PCPs typically decayed to background concentrations over periods ranging from 5 to 150min.

Assessment of Indoor Air Quality in Otorhinolaryngology Clinics

Background and Objectives Otorhinolaryngology clinics are frequently exposed to various air pollutants. This can have a potentially harmful effect on the health of the healthcare personnel. However, there is still a lack of studies on the assessment of indoor air quality in otorhinolaryngology clinics. Therefore, this study aimed to measure indoor air quality in otorhinolaryngology clinics.Subjects and Method In this study, we prospectively measured indoor air quality indices [particulate matter (PM), carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;), total volatile organic compounds (VOCs), PM2.5, Nitrogen dioxide (NO&lt;sub&gt;2&lt;/sub&gt;), carbon monoxide (CO), and ozone] using portable passive air quality monitoring sensors in otorhinolaryngology clinics.Results The mean concentrations of PM, CO&lt;sub&gt;2&lt;/sub&gt;, VOCs, and NO&lt;sub&gt;2&lt;/sub&gt; were significantly higher during office hours than after; however, there was no significant differences in CO and ozone concentration between the two time periods. The proportions of tolerable to poor-quality (exceeding acceptable level) levels of CO&lt;sub&gt;2&lt;/sub&gt;, total VOCs, NO&lt;sub&gt;2&lt;/sub&gt; was 25%, 25%, 12.5% during office hours, respectively. On the other hand, there was no proportion of tolerable to poor-quality level of PM, CO, ozone during office hours.Conclusion We found that otorhinolaryngology clinics are easily exposed to ambient indoor air pollution. Therefore, we suggest implement health-related protective strategies for ambient indoor air pollution in otorhinolaryngology clinics may be needed for healthcare personnel.

Co-Heating method for thermal performance evaluation of closed refrigerated display cabinets

In this study, an application of the adapted Co-Heating methodology for thermal performance evaluation of closed refrigerated display cabinets (RDCs) has been presented. A novel test series comprising three experiments has been developed and demonstrated on a commercial RDC with four doors to evaluate the envelope heat transfer coefficient, thermal inertia, infiltration at idle state and dynamic infiltration caused by door operations. The latter two experiments were conducted in parallel with the condensate collection method for validation of the results for infiltration. It was concluded with good (<10%) conformance between the methods that the infiltration at idle state for the tested RDC is approximately 0.022 kg/s and that one 15 s door opening causes approximately 0.94 kg of ambient indoor air to infiltrate. Additionally, the time, equipment and associated costs for running the tests were compared, and it was concluded that the adapted Co-Heating methodology could substitute the condensate collection method for the evaluation of infiltration while providing additional results on the thermal performance.

Ambient indoor air pollution and its consecutive effect on environment materials and health

The economic cost of urban air pollution is measured by considering household health production function model which consists of health production function, demand function for mitigating activities and demand function for averting activities. To supplement the analysis of cost of illness approach, on the contingent valuation survey is also employed. The ordered logistic regression model is used to analyze the factors affecting willingness to pay for reducing urban air pollution.The total suspended particulate matter (TSPM or PM10) and the respirable suspended particulate matter (RSPM or PM2.5) are considered as criteria pollutants. It is found that PM10and PM2.5 concentration has exceeded the National Ambient Air Quality Standards Suggested by in all the monitoring stations of study area. It is two to three times higher than the average annual standard. The results have shown that cough, dust allergy and asthma are more prevalent in the study area.

Experimental study on the effects of direct sun radiation on the dynamic thermal behavior of a floor-heating system

Radiant floor heating systems (FHSs) are considered reliable heating systems since they maintain the indoor air temperature at the desired value and reduce its fluctuations more efficiently than conventional heating systems do. However, FHSs require an optimal control strategy especially when they are exposed to perturbations such as direct solar radiation or unscheduled crowding. The present study investigates the dynamic thermal response of a FHS exposed to a simulated direct solar radiation that is localized on its upper surface to quantify the potential effects of this exposure and identify the subsequent control issues of the FHS. Three experimental test scenarios were examined by varying the location of the sun patch and its duration. The experimental results show that the tested FHS, primarily regulated by controlling the indoor ambient air temperature, experiences a deficient regulation of the indoor temperature, which leads to an overheating period depending on the sun patch intensity and duration. An overheating of 4 °C compared with the recommended maximum desired value was recorded for duration of approximately 11.5 h after the sun patch was turned-off. The experimental results may be used in further numerical studies to predict the thermal behavior of FHSs exposed to sudden solar patches on their upper surfaces. The FHS design elements (material, thickness, etc.), as well as the control procedures, must be reconsidered to address the issue of overheating under such conditions.

Radioactive and non-radioactive aerosol permeability through two types of analytical filters

AFA analytical filter is the most used one of Petryanov filters in health protection and radiometric and analytical measurements. Therefore, the properties of this filter like efficiency and the permeability of the non-radioactive and radioactive aerosol particles are more important for accurate estimation and protection. AFA Petryanov filters (RSP-20 and RMP-20) are the most popular filters in Russia. In this work, an experimental setup has been constructed to estimate the permeability of the non-radioactive and radioactive aerosol particles through these two type of analytical filters. A standard radon chamber (2 m3), at Ural federal university is used to create radioactive aerosol. Non-radioactive aerosol or ambient aerosol is considered from ambient indoor air. Aerosol diffusion spectrometer (ADS) is used to measure aerosols concentration and number size distribution with range from 1 nm to 10 μm. The activity size distribution is determined with screen diffusion battery and the AIP-2 cascade impactor with range (0.5-20μm). The measurements are repeated before and after filters to study the PFs filters dispersion and permeability for non-radioactive and radioactive aerosols. ADS filter is used to measure the aerosol concentration and number size distribution before and after filters in ambient air with spatial construction. The effect of size modes of the non-radioactive and radioactive aerosols penetrating the filters is studied. At low aerosol concentration, the filters catch all free unattached radon decay products (RDPs) (1-5 nm) and the most collected activity with active median thermodynamic diameter, AMTD, ∼ 20 nm. In the radon chamber at high aerosol concentration, the activity of RDPs free unattached fraction nearly removed. The collected activity with AMTD ∼ 20-40 nm is more significant.

Impact of ventilation method on residential indoor PM dispersion during dust storm events in Saudi Arabia

ABSTRACTDust storms are a major environmental hazard in arid regions such as the Middle East and other parts of Asia including China and Mongolia. The prevalence of dust storms has been widely linked with high atmospheric Particulate Matter (PM) concentrations. The atmospheric PM concentration is considered as being positively correlated with the PM concentration of the indoor environment. High indoor concentrations of PM compromise the Indoor Air Quality (IAQ) leading to adverse impacts on building occupants’ health with increased occurrences of asthma attacks, spread of disease-causing fungus, skin allergies and other ailments. There is, therefore, an increased risk of compromised IAQ in places that experience dust storms. This risk may be exacerbated by the incorporation of mechanical ventilation systems in attempts to condition the indoor ambient air. Instead of minimizing the problem of PM contamination, these systems may potentially nurture it. Using Computational Fluid Dynamics analyzes in ANSYS Fluent, this study seeks to investigate the impact of ventilation method on outdoor-originating indoor PM dispersion within the occupied indoor environment during dust storm events in Saudi Arabia. Four ventilation methods are studied and the one that yields the least amount of particle trajectories terminating within the breathing zone is recommended for use.

Assessment of hygrothermal behavior of newly straw-rape concrete material in various conditions

This article focuses on study of hygrothermal behavior of building made of new bio-concrete based on straw-rape. The assessment was conducted using a numerical study, performed using a coupled heat and mass transfer model which takes into account the temperature dependence of the moisture retention curve. The model consists on coupling of envelope model with mono-zone building ambient air model which takes into account ventilation, occupants production and internal inertia in term of thermal and moisture buffering. The model of building envelope was validated by comparison against experimental data carried out on real scale wall. The results reveal that considering moisture retention curve as a temperature-dependent property leads to better prediction of the relative humidity variation in the material, whereas it has weak influence on temperature variations. However, the overall isothermal model may be enough to predict the temperature and relative humidity variations of the indoor ambient air of building. Results have showed good contribution of the internal thermal inertia to reduce temperature variation of the ambient air of building. In addition, simulations highlighted strong capacity, of the straw-rape concrete, to damp the high variations of outdoor relative humidity for all considered climates, especially in desert climate. This effect conduces to avoid accumulation of moisture in the material thus it may rise the life service of the wall.

Volta Potential Evolution\xa0of Intermetallics in Aluminum Alloy Microstructure\xa0Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

In this work, first-principle density functional theory (DFT) was used to calculate the work function and Volta potential differences between aluminum alloy matrix and two intermetallic phases (Mg2Si and Al2Cu) with varying surface terminations as a function of adhering monolayers (ML) of water. The calculated data were compared with experimental local Volta potential data obtained by the scanning Kelvin probe force microscopy (SKPFM) on a commercial aluminum alloy AA6063-T5 in atmospheric environments with varying relative humidity (RH). The calculations suggest that the surface termination has a major effect on the magnitude and polarity of the Volta potential of both intermetallic phases (IMP’s). The Volta potential difference between the IMP’s and the aluminum matrix decreases when the surface is gradually covered by water molecules, and may further change as a function of adhering ML’s of water. This can lead to nobility inversions of the IMP’s relative to the aluminum matrix. The measured Volta potential difference between both IMP’s and their neighboring matrix is dependent on RH. Natural oxidation in ambient indoor air for 2 months led to a nobility inversion of the IMP’s with respect to the aluminum matrix, with the intermetallics showing anodic nature already in dry condition. The anodic nature of Al2Cu remained with the introduction of RH, whereas Mg2Si became cathodic at high RH, presumably due to de-alloying of Mg and oxide dissolution. The DFT calculations predicted an anodic character of both IMP’s in reference to the oxidized aluminum matrix, being in good agreement with the SKPFM data. The DFT and SKPFM data were discussed in light of understanding localized corrosion of aluminum alloys under conditions akin to atmospheric exposure.

Experimental and numerical investigations of an adsorption water-zeolite heat storage for refrigeration applications

A zeolite 13XBF - water adsorption heat storage for refrigeration purposes is presented in this paper. The system comprises a reactor, in which the adsorption process takes place, and a condenser/evaporator unit. The aim is to be able to recover waste heat, excess solar heat or off-peak electricity (electricity-to-heat), to store it with minor losses and to use the available energy when it is needed, either for cooling and/or for heating.A prototype of the system has been developed and tested. The studied configuration is designed to recover heat from air flows (at up to 300 °C) and to produce cooling of the indoor ambient air (range 12-20°C). The reactor includes only one bed and the entire system is designed to store energy (3 kWh) to provide the desired cooling effect for several hours.Moreover, the heat and mass transfer has been numerically simulated with a CFD software. A 2D model of the sorption storage and a 0D model for the condenser/evaporator unit have been coupled.The experimental results showed that the concept is suitable for the application, but some challenges still exists: heat transfer inside the adsorber (i) and vacuum tightness of the system (ii). The results of the simulation are consistent with the ones from the experiments, demonstrating the suitability of the theoretical model.

Carbon monoxide measurements in homes

Carbon monoxide is one of the indoor air contaminants in homes that causes the most concern among energy efficiency programs. Programs that perform energy upgrades to homes spend substantial effort evaluating carbon monoxide hazards. Furnaces, boilers, water heaters, and ovens/ranges are common sources of carbon monoxide in the indoor environment. The current article presents results of carbon monoxide measurements from two studies that looked at homes that underwent energy efficiency upgrades as part of the U.S. Department of Energy's low-income Weatherization Assistance Program. In the first study, carbon monoxide was measured in the flues of furnaces, boilers, and water heaters, in the exhaust of ovens/ranges, and in the indoor ambient air. Measurements of the appliance combustion gases were done once while at the site, and indoor air measurements were done using dataloggers recording for about a month before and after weatherization. In the second study the focus was only on measured indoor ambient air, also with measurements using dataloggers for about 1 week. The results show that most appliances have carbon monoxide levels within allowable standards, though some are elevated. Regarding indoor ambient air, less than 5% of homes have persistent levels (i.e., for more than 10% of the time) of carbon monoxide of 5 ppm or higher. However, elevated peak levels above 9 ppm are much more common, with about 20%–30% of units in both studies reached 9–10 ppm at least once within a week-long test period. These results show that elevated indoor ambient carbon monoxide is a highly episodic phenomenon, and, therefore, not well addressed by whole-home ventilation. Further, the data suggest that it is the cooking appliances that are most subject to producing short-term elevations of carbon monoxide. The current article also includes a comparison of carbon monoxide before and after retrofits.

Review of Thermal Performance: A Terrace House in Melaka, Malaysia

A field study of residents’ thermal comfort in a naturally ventilated intermediate single storey terrace house was carried out at Merlimau, Melaka. An intermediate single storey terrace house was chosen as a case study and indoor thermal condition measurements were recorded for three days. The indoor ambient temperature, relative humidity and air speed were measured using on-site monitoring equipment to evaluate the thermal performance of this house. A questionnaire survey was also conducted involving all occupants to determine their thermal comfort perception of the same case study house. The aim of this study is to analyse the indoor thermal condition of an intermediate single storey terrace house in order to propose architectural features to climatically adapt to the local climate. In naturally ventilated condition, results showed that this house is thermally uncomfortable and the indoor thermal condition was between 2.7°C to 5.9°C higher than suggested temperatures stipulated in ASHRAE Standard 55. Consistently, five out of eight occupants or less than 80% of occupants voted the house as thermally acceptable according to ASHRAE Standard 55.

A Survey of the quantity and type of biological aerosols in selected wards of a teaching hospital in Ghazvin.

IntroductionBioaerosols are agents that can cause infection, allergy or induce other toxic effects in the human body. If the person exposed to such particles is not capable of their destruction or elimination from the body, the established chemical and physiological disorders can result in disease or death. The aim of this study was to assess the concentrations of bioaerosols in several wards of a teaching hospital.MethodsGiven that gas air-conditioners (split and window types) were used for ventilation in the eye operating room, internal intensive care unit, and the respiratory isolation room, these wards were selected for passive sampling. Sterile plates containing culture medium were exposed for two hours to the wards’ indoor ambient air. After this time, they were transferred to a lab to undergo incubation, colony count, and identification of the microorganisms. The data were analyzed using SPSS software, version 18, and the significance level of less than 0.05 was used.ResultsBased on our findings, the highest colony-forming bacterial unit was observed 22 cfu/plate/h in the eye operating room and, the highest colony-forming fungal unit was observed 4 cfu/plate/h in the internal intensive care unit. Based on the results of the differential tests, the most prevalent bacteria identified were Staphylococcus epidermidis (75%) in the air of eye operating room and Staphylococcus saprophyticus (52%) in the internal intensive care unit and isolation room. The most prevalent identified fungi in the air of selected wards were related to Alternaria alternata (43%), Aspergillus flavus (24%), Penicillium (36%) and Curvularia (21%) types. Based on Spearman’s correlation test, no significant relationship was observed between the factor of temperature and the number of fungal and bacterial colonies (r = 0.201, p = 0.42; r = −0.197, p = 0.41). Moreover, a meaningful relationship was observed only between the number of individuals and the bacterial colonies present in the air (r = 0.749, p = 0.0001).ConclusionComparing the number of diagnosed colonies by 25 cfu/plate/h value showed that the numbers of colonies in all samples were lower than the mentioned values. So, the air-conditioning systems’ performance in reducing the number of bioaerosols in the studied wards was satisfactory. However, since the remaining bacterial and fungal contamination can cause serious infections in patients, it is highly necessary that the cleaning intervals and replacement time points of such filters be programmed based on the number of individuals present in the wards and their active surgical hours.