Outdoor Air Environment Research Articles

Simulation Study of the Capture and Purification Performance of Exhaust Fume Systems in Chinese Commercial Kitchens—Case Study in Tianjin

A Chinese commercial kitchen fume exhaust (CCKEF) system mainly consists of a wall-mounted canopy hood, air duct and terminal electrostatic purifiers, the capture and purification performance of which should be guaranteed to obtain satisfactory indoor and outdoor air environment in engineering applications. However, few studies have focused on the operation performance of CCKEF systems. This study was aimed at providing a simulation method to investigate the operation performance of such systems. The simulation model of a representative CCKEF system was established using CFD software and validated with measured temperature, air velocity and purification efficiency with a deviation within 10%. The validated model was used to predict the indoor air environment and purification efficiency of the CCKEF system under different working conditions. The results showed that the temperature of transfer air from adjacent rooms had a greater impact on the thermal environment of the cooking area than the surface temperature of stoves. The exhaust air volume had a significant influence on both the indoor air environment and purification efficiency. CCKEF system was suggested to be operated at the optimum airflow according to the simultaneous coefficient of stoves as the energy consumption of the system can be saved by 3.75%.

Comparative assessment of indoor and outdoor air environment of poultry farms in Edo State, Nigeria

Intensive poultry farming creates the ideal environment for pathogen concentration and transmission. The presence of thousands of birds in an enclosed, warm, and dusty atmosphere is ideal for the transmission of infectious diseases from birds to humans. This study was conducted to assess the indoor and outdoor air quality of different poultry types in Edo State, Nigeria. The physicochemical conditions of the air around the poultry environments differed with location and poultry types. The concentrations of carbon dioxide (CO2,), nitrous oxide (N2O), hydrogen sulphide (H2S) as well as particulate matter (PM10) were all within recommended limits established by the World Health Organization. However, significant elevations in Ammonia (NH3) and sulphur dioxide (SO2) levels were observed in substandard poultry farms across the locations. Total bacterial counts ranged from 1.38CFU/m5 – 90.35 x105CFU/m3 irrespective of location and poultry type. Within the poultry types, bacteria count inside the poultry environment (3.11 x105CFU/m3) significantly differed from concentrations outside the poultry environment (22.58 x105CFU/m3, p<0.05). The Lowest microbial counts were obtained in the standard poultry farms. Molecular identifications revealed the presence of Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, Bacillus subtilis as the bacterial isolates whereas Fusarium oxysporum, Aspergillus niger, Rhizopus stolonifer, Trichoderma polysporum, Aspergillus fumigatus were the fungal isolates. Staphylococcusaureus was the most predominant bacterial species (25%) while Aspergillus niger was the most predominant fungal species (30%).

Design characteristics on the indoor and outdoor air environments of the COVID-19 emergency hospital

According to the discussion of the design method and operational effect for Wuhan Huoshenshan Hospital, this paper summarized the design control points of indoor and outdoor environment of COVID-19 emergency hospital. Based on the design of Wuhan Huoshenshan Hospital, this paper analyzed and discussed the site design, building layout, three-zones and two-passages, the design scheme of the ventilation and air conditioning system for negative pressure ward and negative pressure isolation ward, air distribution, as well as some other key designs for COVID-19 emergency hospital. The design points were summarized and refined. The design methods and technology requirements of the COVID-19 emergency hospital were provided in this study, such as ventilation and air conditioning system setting, ventilation quantity of wards, pressure gradient control measures among different areas, upper and lower air distribution, filter setting mode and distance of air inlet and outlet, which could benefit to provide references for the design of similar projects in the future.

MoS2 Nanoflowers Decorated with Au Nanoparticles for Visible-Light-Enhanced Gas Sensing

Highly sensitive and selective detection of trace nitrogen dioxide (NO2) in a complex outdoor air environment is an urgent need to guarantee human health and a beautiful environment. The effective combination of heterostructure and light irradiation is an important strategy to achieve high-performances gas sensors. However, the effect of light irradiation on gas-sensitive properties of heterostructure materials is not yet clear, and it is urgent to clarify the relationship between light irradiation and heterostructure for gas-sensing materials. Herein, a 530 nm-light-assisted Au–MoS2 gas sensor with a low detection limit as well as robust antihumidity interference ability is developed through introducing the localized surface plasmon resonance (LSPR) effect of Au nanoparticles (NPs). Under 530 nm light illumination, a Au–MoS2 gas sensor can achieve limit detection of NO2 as low as 10 ppb without operating temperature along with robust antihumidity ability. The optical simulation and experimental results show that the modification of MoS2 by Au NPs (diameter: 30 nm) combined with the matching light-assisted (530 nm) gas detection mode can make MoS2 fully absorb visible light and effectively improve the extinction cross section by taking full advantage of the LSPR effect, which is the primary reason for the enhanced performances of a MoS2-based gas sensor. This work provides theoretical and experimental guidance for gas sensors to effectively enhance the ability of gas detection by means of the light-assisted mode at room temperature, which opens up a unique approach to design high-performance gas sensors for trace-level gas detection.

Fingerprinting ambient air to understand bioaerosol profiles in three different environments in the south east of England

Molecular and chemical fingerprints from 10 contrasting outdoor air environments, including three agricultural farms, three urban parks and four industrial sites were investigated to advance our understanding of bioaerosol distribution and emissions. Both phospholipid fatty acids (PLFA) and microbial volatile organic compounds (MVOC) profiles showed a different distribution in summer compared to winter. Further to this, a strong positive correlation was found between the total concentration of MVOCs and PLFAs (r = 0.670, p = 0.004 in winter and r = 0.767, p = 0.001 in summer) demonstrating that either chemical or molecular fingerprints of outdoor environments can provide good insights into the sources and distribution of bioaerosols. Environment specific variables and most representative MVOCs were identified and linked to microbial species emissions via a MVOC database and PLFAs taxonomical classification. While similar MVOCs and PLFAs were identified across all the environments suggesting common microbial communities, specific MVOCs were identified for each contrasting environment. Specifically, 3,4-dimethylpent-1-yn-3-ol, ethoxyethane and propanal were identified as key MVOCs for the industrial areas (and were correlated to fungi, Staphylococcus aureus (Gram positive bacteria) and Gram negative bacteria, R = 0.863, R = 0.618 and R = 0.676, respectively) while phthalic acid, propene and isobutane were key for urban environments (correlated to Gram negative bacteria, fungi and bacteria, R = 0.874, R = 0.962 and R = 0.969 respectively); and ethanol, 2-methyl-2-propanol, 2-methyl-1-pentene, butane, isoprene and methyl acetate were key for farms (correlated to fungi, Gram positive bacteria and bacteria, R = 0.690 and 0.783, R = 0.706 and R = 0.790, 0.761 and 0.768). The combination of MVOCs and PLFAs markers can assist in rapid microbial fingerprinting of distinct environmental influences on ambient air quality.

The Analysis and Design of Small Air Purifier

This design is positioned in the outdoor air environment is increasingly deteriorated premise through the improvement or redesign, to improve people’s workplace environment for desk type air purifier; and stylish innovation to meet the fast-paced city life crowd physiological and psychological needs to improve the quality of life and work purposes. Innovation of a product, in addition to hoping to facilitate people’s lives, but also hope to gradually change the way people live and work to improve people’s spiritual pursuit, promoting the formation of the concept of healthy living, create a harmonious and warm office environment.

The difference of nasal mucosal cytology features in gas station workers compared to non-gas station workers

The pollutants contained in an outdoor air environment for example gasoline vapors can cause epithelial inflammation, metaplasia, and dysplasia. This study aimed to determine the difference in cytological nasal mucosa between gas station workers and non-gas station workers. This research used a cross-sectional design. There were 80 samples with inclusion criteria: aged 20-50 years, worked more than 3 months, consisting of 40 gas station workers (exposed group) and 40 non-gas station workers (unexposed group) who did not use nasal drops in the last ten days. The exclusion criteria of both groups were: 1) patients with acute rhinitis, 2) had nasal trauma, 3) had nasal surgery, 4) consume alcohol, 5) history of allergic rhinitis, and 6) refused to participate in the study. All samples performed brushing at 1/3 anterior nose inferior turbinate and cytology examination. The statistical analyses used X2 tests. From the exposed group we found 18 (45%) with inflammation, 17 samples (42.5%) with metaplasia, and 9 samples (22.5%) with dysplasia, while in the unexposed group there were 10 (20.5%) with inflammation, 4 (10.0%) with metaplasia and 2 (5.0%) dysplasia. There were statistically significant differences in nasal mucosal cytology, particularly metaplasia (p: 0.001; RP: 6.65; 95% CI: 1.78-27.01) and dysplasia (p: 0.023; RP: 5.52; 95% CI: 1.22-32.10) between both group samples. It can be concluded that there are statistically significant differences involving metaplasia and dysplasia in nasal mucosa cytology features of gas station workers compared to non-gas station workers.

Comfort IAQ – a new tool to simulate the indoor particulate matter pollution in relation to the chosen supply air filter quality

Many factors are rather well known for their ability to create a good indoor air climate, but when it comes to airborne particles, there is no great deal of documentation to consult and set requirements. Nor are there much of other specific guidelines. The new, product-neutral and free online calculation tool Comfort IAQ helps to understand the mechanisms behind IAQ and gives a good indication on what would be the impact on indoor air quality (IAQ) due to air exchange, outdoor air environment, air filter selection and building envelope characteristics. Comfort IAQ allows to simulate the concentrations of Particulate Matter (PM1, PM2.5, PM10) in a specific ventilated room, depending on the chosen supply air filter quality. To model the room and the supply air conditions in a realistic way, Comfort IAQ allows to define besides outdoor air conditions (ODA) also the room dimensions, the air changes, the recirculation air rate as well as the supply air filter quality (based on ISO 16890, EN779 or ASHRAE 52.2). Based on these values, the Comfort IAQ tool provides an estimation of the indoor particle concentration and gives engineers and planers a good tool to optimize the Indoor Air Quality, by choosing the best combinations of supply air filter qualities and ventilation rates for a specific application. The algorithms in the online tool Comfort IAQ have been developed by Lars Ekberg, (Docent-installallationsteknik, Chalmers Tekniska Högskola) and the accuracy of the calculations was verified by comparing them with measurements in a full-scale test chamber.

Experimental study on cascade heat pump dryer with a solar collector under low temperature outdoor air environment

A heat pump dryer can save more energy than other dryers since its drying efficiency is 2-3 times higher than that of other types of dryers. However, the lower bound of evaporating temperature for an R134a heat pump cycle ranges from 5 to 10?C, when the outdoor air temperature closely approaches the evaporating temperature, it experiences reduced efficiency and ultimately becomes inoperable. To address this issue, a cascade heat pump dryer equipped with a solar collector was considered in order to examine the operability and efficiency of the heat pump cycle, depending on changes in the outdoor air temperature in wintertime. The changes in cascade cycles, depending on the temperature in a drying chamber, were also observed. The results showed that the average coefficient of performance (COP) of the cascade heat pump dryer was approximately 2.6 under the temperature range of ?10 to 20 ?C. An electrical heater whose COP is less than one should be used in that temperature range. It was also found that COP of the dryer increased by approximately 35% when using a solar collector under a low outdoor air temperature environment.

Prevalence of bio-aerosols in the outdoor air environment in Uyo Urban, Akwa Ibom state, Nigeria

Outdoor bio-aerosols quality in Uyo urban was evaluated for their prevalence using settle plate (culturebased) method. Five (5) locations were established for wet and dry season sampling which included Urban Center, Housing Estate, Local Residence, Open Market and Secretariat complex. Mean viable plate counts of heterotrophic bacteria ranged between 1.386 × 103 (wet season) and 2.018 × 103 (dry season) in Urban Center; 4.82 × 102 (wet season) and 9.64 × 102 (dry season) in Housing Estate; 4.22 × 102 (wet) and 1.476 × 103 (dry) in Local Residence; 1.386 × 103 (wet) and 2.470 × 103 (dry) in Open Market, and 7.23 × 102 (wet) and 1.024 × 103 (dry) in Secretariat Complex while the mean viable plate counts of heterotrophic fungi ranged between 9.94 × 102 (wet) and 1.777 × 103 (dry) in Urban Center; 1.054 × 103 (wet) and 1.265 × 103 (dry) in Housing Estate; 7.23 × 102 (wet) and 1.536 × 103 (dry) in Local Residence; 1.325 × 103 (wet) and 2.048 × 103 in Open Market, and 6.93 × 102 (wet) and 1.084 × 103 in Secretariat Complex. Bacteria isolated were Micrococcus nishinomiyaensi, Staphylococcus aureus, Escherischia coli, Bacillus subtilis, Serratia marcescens, Staphylococcus saprophyticus, Shigella dysenteriae, Proteus vulgaris, Salmonella indica, Pediococcus acidilactici, Staphylococcus albus, Pseudomonas aeruginosa, Micrococcus roseus. The fungi isolated included Aspergillus glaucus, Geotricum sp., Verticillium sp., Pichia sp., Candida tropicalis, Phoma sorghina, Fusarium sp., Aspergillus niger, Absidia sp., Cladosporium carrionil, Candida albicans, Rhizopus oligosporus, Alterneria alternate, Botrytis cinerea, Aspergillus flavus, Epicoccum nigrum, Diplodia seriata, Aspergillus fumigates, Eurotium sp., Penicillium expansum, Sacchromyces cerevisiae, Monilia sp., Humicola sp., Cephalosporium sp., Aspergillus clavatus, Scopulariopsis sp., Penicillium italicum, Penicillium nalgiovense, Trichoderma viride and Moniliella acetoabutens. Bacillus subtilis showed 80% prevalence in both wet and dry seasons. The only fungal isolate that showed 100% prevalence during wet season was Aspergillus glaucus. Escherichia coli were encountered in the open market and urban center stations revealing the unsanitary status of the environment. Many of the microorganisms isolated have been implicated in various human ailments and their effects may be curtailed by adopting improved wastes management approaches in Uyo City Bio-aerosol concentration was found to be high in dry season than wet season. This is because of increase in suspended particulate matter in atmospheric air. The present study has provided evidence of microbial load in outdoor ambient air at different locations.

Concentration of environmental fungal and bacterial bioaerosols during the monsoon season

Rain has been known to remove aerosol particles in air environments. The aerosol particles were captured and removed from the air by rain and the concentration of aerosol particles significantly decreased after rain events. Therefore, rain is regarded as having a good effect on air environments in terms of the respiratory health of the general public. However, humid environments produced by long-term rain events such a monsoon may be a sufficient condition for the growth of microorganisms and vibrations because of the splashing of droplets may facilitate the aerosolization of ground microorganisms. We therefore hypothesize that the rain may increase concentrations of bioaerosols in outdoor air environments, thereby possibly influencing respiratory diseases.To verify this hypothesis, at the initial stepwise approach, we measured the concentration of airborne biological particles before, after, and during rain in a monsoon season. The measurement data of the concentration of fungal particles and bacterial particles show quantitatively that the bioaerosol concentrations during the rain event are several times higher than the concentration of the bioaerosols in the condition of no rain.

Study on the suspended particulate matter (SPM) and polycyclic aromatic hydrocarbons (PAHs) in indoor and outdoor air environment along the main road

Study on the suspended particulate matter (SPM) and polycyclic aromatic hydrocarbons (PAHs) in indoor and outdoor air environment along the main road

Chlorophenols, chlorocatechols and chloroguaiacols induce DNA base oxidation in human lymphocytes ( in vitro)

Phenolic compounds are strong environmental toxicants, which are found in food, drinking water as well as in the indoor and outdoor air environment. In this work we investigated the effect of low concentrations of 0.2, 1 and 5 μg/ml of 2,4,5-trichlorophenol (2,4,5-TCP), pentachlorophenol (PCP), 4,6-dichloroguaiacol (4,6-DCG), tetrachloroguaiacol (TeCG), 4,5-dichlorocatechol (4,5-DCC) and tetrachlorocatechol (TeCC) on DNA bases oxidation in human peripheral blood lymphocytes. The analysis was performed using alkaline single cell gel electrophoresis (the comet assay). To detect oxidized pyrimidynes and purines we used the repair enzymes such as endonuclease III and formamidopyrimidine-DNA glycosylase. DNA oxidation was expressed as a percentage of comet tail, which was formed after the xenobiotics treatment. The obtained results showed that all the compounds examined were able to oxidize DNA bases in human lymphocytes. It was also observed that pyrimidine bases were more strongly oxidized in comparison to purine ones. Finally, it was found that chlorinated catechols and TeCC in particular, revealed a higher oxidative potential in comparison to chlorophenols and chloroguaiacols, and a rise in the number of chlorine atoms in the compound from each group examined led to an increase in DNA bases damage.

Study On Respirable Suspended Particulates and Polycyclic Aromatic Hydrocarbons in Indoor and Outdoor Air

To study the concentration change of respirable suspended particulate (RSP) in indoor and outdoor air environment, a new portable sampler (AND-sampler) was made. The sampler could collect particles above 10 microns, 2 to 10 microns, and below 2 microns in aerodynamic diameter separately. The relationship between the airborne particulate concentration in indoor and outdoor air environment varied with the aerodynamic diameter of the particles. The concentration of RSP in indoor air environment increased in proportion to that in outdoor environment. Polycyclic aromatic hydrocarbons (PAH) concentration in airborne particulate also varies with the aerodynamic diameter of the particles. Fine particles below 2 microns in aerodynamic diameter contains high concentration of PAH. The PAH concentration in indoor air environment increases in proportion to that in outdoor air.

Study on the suspended particulate matter(SPM) around a crossroad, outdoor and indoor air environment. Report on measurements using portable SPM samplers.

The concentration change of suspended particulate matter (SPM) in indoor and outdoor air environments was studied. Since the respiratory absorption of particles is markedly different according to their size, a new personal sampler (SPMP-sampler) was made. The sampler could collect particles above 10μm, 2 to 10μm, and below 2μm in aerodynamic diameter separately. SPM concentration using the SPMP-sampler was almost linear to the results of using a Marple Personal Cascade Impactor. The linear equation wasy=0.976x+3.88(μg/m3)(r=0.95)where x and y are the SPM concentration measured using the SPMP-sampler and the Marple Personal Cascade Impactor, respectively.The SPM concentration in a main crossroad air environment changed rapidly. The SPM concentration in the outdoor air environment of the residential areas near the crossroad was greatly reduced compared with the crossroad, but still much higher than in rural areas. The relationship between the particle concentration in indoor and outdoor air environments varied with the diameter of the particles. The SPM concentration in the indoor air environment linearly increased according to the increase of that in the outdoor environment.The polycyclic aromatic hydrocarbons (PAH) concentration in particles also changed sharply depending on their diameter. Fine particles below 2μm in diameter had a high PAH concentration.