Characterizing the performance of a DIY air filter

Air filtration serves to reduce concentrations of particles in indoor environments. Most standalone, also referred to as portable or in-room, air filtration systems use HEPA filters, and cost generally scales with the clean air delivery rate. A 'do-it-yourself' lower-cost alternative, known as the Corsi-Rosenthal Box, that uses MERV-13 filters coupled with a box fan has been recently proposed, but lacks systematic performance characterization. We have characterized the performance of a five-panel Corsi-Rosenthal air filter. Measurements of size-resolved and overall decay rates of aerosol particles larger than 0.5 microns emitted into rooms of varying size with and without the air filter allowed for determination of the apparent clean air delivery rate, both as a function of size and integrated across particle sizes. The measurements made in the different rooms produced similar results, demonstrating the robustness of the method used. The size-integrated apparent clean air delivery rate increases with fan speed, from about 600 to 850 ft3 min-1 (1019 to 1444 m3 h-1). Overall, our results demonstrate that the Corsi-Rosenthal filter efficiently reduces suspended particle concentrations in indoor environments.

Study on Self-Cleaning Time and Suspended Particle Distribution in Medical Clean Room

CFD numerical simulation of clean room in Class D medical factory was carried out and compared with the actual measurement to verify the feasibility of the simulation method. On this basis, four typical air flow organizations were simulated and compared by changing air change rate from two directions of self-cleaning time and suspended particle concentration field. According to the simulation results, in order to meet the self-cleaning time within 20 min, the best air change rate should be between 15/h and 25/h. Different air flow organizations have different self-cleaning capacity, and the value of air change rate can be relatively small in the form of single-side supply same-side down return. Different airflow organizations have different suspended particle distribution characteristics, and there are differences in the applicable scenarios, and the applicability of the top supply down return is the best.

Reaction of radiometric parameters to atmospheric pollution: Part I - Variation over time

The drive for indust rial development h... ... 100 to large scale urbanisation and result,.-. d in theinjec tion of good amount of suspended particle.. and gaseous substances into the atmosphere. The m..er-abuscof the capac ity .of the atmosphere to sustain the equilibrium is bound to disturb the heal budget of the earthatmospheresystem. Radiometric parameters of the atmosphere give an early indication of the trends in the longtermclimatic changes. Whi le the global rad iant exposure is no t likely to show perceptible changes due to theincreased scauering by the pollutants, I ~ ~ diffuse radiant el(p(ls~re and the direct so.l3! irradianc~ respond qu icklyto the changes In the atmospheric conditions. Various controlling factors like humidity. soi l moist ure and cloud"have d ifferent effects on the terres trial radiant energy and the changes in thi s energy OI..'Cur slowly and ta ke longtime to affect the climate at a place. But the general trend is indicated by the increased diffuse component in thedi rect sola r rrmdiances and in the net outgoing terrestrial radia nt energy. The responses arc clearly indicative.part icularly ,II Punc......here the industrial activiti es grew at a phenomenal rate during the past fifteen years.

A Four-Step Method for Estimating Suspended Particle Size Based on In Situ Comprehensive Observations in the Pearl River Estuary in China

The suspended particle size has great impacts on marine biology environments and biogeochemical processes, such as the settling rates of particles and sunlight transmission in marine water. However, the spatial–temporal variations in particle sizes in coastal waters are rarely reported due to the paucity of appropriate observations and the limitations of particle size retrieval methods, especially in areas with complex optical properties. This study proposed a remote sensing-based method for estimating the median particle size Dv50 (calculated with a size range of 2.05–297 μm) that correlates Dv50 with the inherent optical properties (IOPs) retrieved from in situ remote sensing reflectance above the water’s surface (Rrs(λ)) in the Pearl River estuary (PRE) in China. Rrs(λ) was resampled to simulate the Multispectral Instrument (MSI) onboard Sentinel-2A/B, and the wavebands in 490, 560, and 705 nm were utilized for the retrieval of the IOPs. The results of this method had a statistical performance of 0.86, 18.52, 21.28%, and −1.85 for the R2, RMSE, MAPE, and bias values, respectively, in validation, which indicated that Dv50 could be estimated by Rrs(λ) with the proposed four-step method. Then, the proposed method was applied to Sentinel-2 MSI imagery, and a clear difference in Dv50 distribution which was retrieved from a different time could be seen. The proposed method holds great potential for monitoring the suspended particle size of coastal waters.

Laboratory studies of suspended particle volume concentration in atmosphere using a smartphone

The article presents the results of laboratory studies of the effect of volume concentration of suspended particles in contrast to the luminous slits image obtained by smartphone cameras of SAMSUNG Galaxy A3 and Honor 8 Lite. Experimentally it was found that a pattern of change in contrast to the luminous slits image from the volumetric concentration of suspended particles appears under ambient light. The pattern of contrast change can be expressed by an exponential function. The correlation coefficient is 0.97. Cigarette smoke was used as suspended particles.

Fire and water: contaminants and clearance following uncontrolled fires

There is a growing body of evidence surrounding the implications of uncontrolled bushfires and wildfires on water. This topic has importance from an ecological perspective, and significance for human health as it has consequences for drinking water quality and supply. Against the backdrop of climate change, it is especially important to holistically understand the impact of fire on water. This review took a systematic approach to establish a comprehensive overview of the changes occurring in freshwater systems following uncontrolled wildfires and bushfires. Screening of 16,551 results obtained from Web of Science, PubMed, and MEDLINE resulted in 111 manuscripts suitable for inclusion. The impact of fire across a wide range of water quality indicators either relative to pre-fire measurements or reference sites was examined qualitatively (increase/decrease) and where possible quantitatively (% change or difference). Factors included biomass, indicator species and species diversity, metals, nutrients, salts, polycyclic aromatic hydrocarbons, particulates and turbidity, pH, conductivity, temperature, and water course morphology. Evidence focused largely on short to medium term impacts (e.g. within 2 years of the fire event), with only a subset of studies reporting on longer term changes in response to fire. We found that bushfire has acute and long-lasting effects on water in terms of physical (e.g. decreased suspended particle size), chemical (e.g. increased nutrient concentration), and biological (e.g. decreased species diversity) characteristics. There was also evidence of resilience and recovery. We urge future work to consider measures that will fulfil both environmental and human health considerations, to allow more integrated insight into the impacts of fire on water.

Sediment Transport in Shallow Waters as a Multiphysics Approach

Suspended particle and bed-load transport are usually high during flooding events. For that reason, sediment transport is an important feature to be taken into account when studying floods. Measures that aim to mitigate the negative impacts of floods depend on such studies. Sediment transport phenomena are complex due to their coupling behavior with fluid flow. Due to the erosion and sedimentation of particulate matter, the ground surface changes during the passing of a flood. The courses of unregulated rivers and wadis after floods are different than those before floods. Flowing water transports sediments, and vice versa; sediment redistribution affects the flow of water due to changes in the ground surface and other factors. Computer simulations of sediment transport must take the coupling between water flow and transport processes into account. Here, a multiphysics approach in such a coupled model is presented. Shallow water equations (SWE) representing water height and velocity are coupled with equations for suspended particulate matter and bed loads. Using COMSOL Multiphysics software, an implementation is presented that demonstrates the capability and feasibility of the proposed approach. The approach is applied to the problems of scouring and sedimentation at obstacles, which are particularly important for ensuring the stability of bridges across rivers and wadis.

Seasonal variation of suspended sediment and its relationship with turbidity in Cam - Nam Trieu estuary, Hai Phong (Vietnam)

We analyzed the seasonal variation of suspended sediment and its relationship with Turbidity in Cam - Nam Trieu estuary based on data measured during three different seasons: Early wet season (May 2015), wet season (September 2015) and dry season (January 2016). The results highlighted the seasonal variation of suspended particle matter (SPM) concentrations with river flow. The average SPM concentration was highest during the dry season, with 62.95 mg/L. They were not significantly different between the early wet and wet seasons, with 59.65 mg/L and 50.94 mg/L, respectively. This study also demonstrated a strong dependence between SPM and Turbidity in the study area. The coefficients of determination varied from 0.867 to 0.971 (linear relationship), and from 0.95 to 0.991 (proportional relationship). Therefore, turbidity can be used to estimate SPM concentration. However, this relationship changed markedly with the seasons, and hence when determining SPM concentration, seasonal factors must be considered.

Glitter Interference On Photosynthetic Rates of A Submerged Macrophyte (Egeria Densa)

This study analyzed the photosynthetic rates (by the light and dark bottle method) of the submerged macrophyte Egeria densa in the presence of three concentrations of glitter: 0.0235 g (T1/T4), 0.0117 g (T2/T5) and 0.0058 g (T3/T6), as well in its absence (control treatment, CT1 and CT2). About 800 apical fragments of E. densa were distributed in 8 subtreatments (4 under light conditions and 4 in the dark to obtain respiration), with 100 specimens in each. The CT showed the highest net photosynthesis rate (PN = gross photosynthetic (PG) rate subtracted from respiration (RD)) of E. densa, with 59.3%, 32.8%, 13.0% higher compared to T1, T2 and T3, respectively. At T3 it was observed the highest mean respiration rate (RE) o E. densa and at T1, the lowest. Comparing PN with RD, we found that the photosynthetic process was, on average 3.5, 2.47, and 2.93 times higher in CT, T1, T2, and T3, respectively. The presence of glitter may have increased the reflectance of water, as it is a suspended particle and reflected light intensely, considering that it is a metal coated particle. Glitter reflects radiation, decreasing the light absorption process, compromising the use of underwater radiation by E. densa. The microplastic interferes with the absorption of light necessary for photosynthetic processes, reducing them, enabling an imbalance in the ecosystem.