Morphological study on particulate matter of Kathmandu valley

Rauniyaar, Jyoti; Aryal, Girja Mani; Neupane, Bhanu

doi:10.3126/bibechana.v16i0.19190

Cited by 5 publications

(7 citation statements)

References 10 publications

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“…As shown in Fig. 3B, a total of 98% particles were smaller than 10 μm, which is in consistent with a recent study reported by our group (Rauniyaar, Aryal & Neupane, 2019). Thus, the filtering efficiency of the face mask reported in Fig.…”

Section: Discussionsupporting

confidence: 93%

“…Bright filed microscopy is frequently used in the determination of number density of micro-meter sized objects (Ricardo & Phelan, 2008; Drey, Graber & Bieschke, 2013; Rauniyaar, Aryal & Neupane, 2019). The accuracy in such measurement is high if: (1) light scattering efficiency of an object to be imaged is high so they can be contrasted from the background, and (2) individual dispersion in the field of view can be achieved.…”

Section: Discussionmentioning

confidence: 99%

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Optical microscopic study of surface morphology and filtering efficiency of face masks

Neupane

Mainali

Sharma

et al. 2019

PeerJ

Self Cite

114

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BackgroundLow-cost face masks made from different cloth materials are very common in developing countries. The cloth masks (CM) are usually double layered with stretchable ear loops. It is common practice to use such masks for months after multiple washing and drying cycles. If a CM is used for long time, the ear loops become stretched. The loop needs to be knotted to make the mask loop fit better on the face. It is not clear how washing and drying and stretching practices change the quality of a CM. The particulate matter (PM) filtering efficiency of a mask depends on multiple parameters, such as pore size, shape, clearance, and pore number density. It is important to understand the effect of these parameters on the filtering efficiency.MethodsWe characterized the surface of twenty different types of CMs using optical image analysis method. The filtering efficiency of selected cloth face masks was measured using the particle counting method. We also studied the effects of washing and drying and stretching on the quality of a mask.ResultsThe pore size of masks ranged from 80 to 500 μm, which was much bigger than particular matter having diameter of 2.5 μm or less (PM2.5) and 10 μm or less (PM10) size. The PM10filtering efficiency of four of the selected masks ranged from 63% to 84%. The poor filtering efficiency may have arisen from larger and open pores present in the masks. Interestingly, we found that efficiency dropped by 20% after the 4th washing and drying cycle. We observed a change in pore size and shape and a decrease in microfibers within the pores after washing. Stretching of CM surface also altered the pore size and potentially decreased the filtering efficiency. As compared to CMs, the less frequently used surgical/paper masks had complicated networks of fibers and much smaller pores in multiple layers in comparison to CMs, and therefore had better filtering efficiency. This study showed that the filtering efficiency of cloth face masks were relatively lower, and washing and drying practices deteriorated the efficiency. We believe that the findings of this study will be very helpful for increasing public awareness and help governmental agencies to make proper guidelines and policies for use of face mask.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Optical microscopic study of surface morphology and filtering efficiency of face masks

Neupane

Mainali

Sharma

et al. 2019

PeerJ

Self Cite

114

View full text Add to dashboard Cite

show abstract

“…As shown in Fig. 3B, 98% particles were smaller than 10μm which is in consistent with a recent study reported by our group (Rauniyaar, Aryal & Neupane, 2019). Thus, the filtering efficiency of face mask reported in Fig.…”

Section: Filtering Efficiencysupporting

confidence: 92%

“…3B. Around 98% particles in ambient air was smaller than 10μm which is consistent with a recent study reported by our group (Rauniyaar, Aryal & Neupane, 2019).…”

Section: Filtering Efficiencysupporting

confidence: 92%

Peer Review #1 of "Optical microscopic study of surface morphology and filtering efficiency of face masks (v0.2)"

2019

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Background. Low cost face masks made from different cloth materials are very common in developing countries. The cloth masks are usually double layered with stretchable ear loops. It is common practice to use such masks for months after multiple washing and drying cycles. If a cloth mask is used for long time, ear loops get stretched. The loop requires to be knotted to make the mask loop fit better on the face. It is not clear how washing and drying and stretching practices change the quality of a cloth mask. Particulate matter filtering efficiency of a mask depends on multiple parameters, such as pore size, shape, clearance, and pore number density. It is important to understand the effect of these parameters on the filtering efficiency. Methods. We characterized the surface of twenty different types of cloth masks using optical image analysis method. The filtering efficiency of selected cloth face masks was measured using particle counting method. We also studied the effect of washing and drying and stretching on quality of a mask. Results. The pore size of masks ranged from 80-500 micrometer which was much bigger than particular matter having diameter of 2.5 µm or less (PM 2.5) and 10 µm or less (PM 10) size. The PM 10 filtering efficiency of four of the selected masks ranged from 63-84%. The poor filtering efficiency may have arisen from larger and open pores present in the masks. Interestingly, we found that after 4 th washing and drying cycle efficiency dropped by 20%. We observed change in pore size and shape and decrease in microfibers within the pores after washing. Stretching of cloth mask surface also altered the pore size and potentially decreased the filtering efficiency. As compared to cloth masks, the less frequently used surgical/paper masks had complicated networks of fibers and much smaller pores in multiple layers in comparison to cloth masks, therefore had better filtering efficiency. This study showed that filtering efficiency of cloth face mask was relatively lower and washing and drying practices deteriorated the efficiency. We believe that the findings of this study will be very helpful to increase public awareness and help governmental agencies to make proper guidelines and policies for use of face mask.

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“…Several studies have suggested that mineral distribution and composition of airborne particulate matter is important to understand the health impact of a region [13,29,30,31,32,33,34,35]. Recently, we reported an optical microscopic study on the air dust samples collected from different core areas of Kathmandu Valley in April 2018 [36]. It was found that significant number particles in the samples to be asymmetric.…”

Section: Introductionmentioning

confidence: 96%

Characterization of airborne dust samples collected from core areas of Kathmandu Valley

Neupane

Sharma

Giri

et al. 2020

Heliyon

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Although there are several reports on spatial and temporal variation of air quality of Kathmandu Valley, the morphological and mineralogical characteristics of particulate matter are very limited or none. In this study, we report on the mineralogical and morphological analysis of airborne particulate matter collected from densely populated core areas of Kathmandu Valley using spectroscopic and microscopic techniques. The Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD) data showed the presence of clay minerals, crystalline silicate mineral, carbonate minerals, and asbestiform mineral in the dust samples. The field emission scanning electron microscopic analysis confirmed the existence of particles having diverse morphology with some of the particles having aspect ratio as high as twenty; indicating the existence of asbestiform type minerals. Based on SEM-EDX data, we found that the relative distribution of elements to be different in different samples and C, O, Mg, Ca, and Si were the major elements in the dust samples. Interestingly, the XRD data analysis showed that in all the samples quartz mineral having high degree of crystallinity was present. The XRD measurement was also carried out in three different brands of cement samples. Few minerals present in dust samples were also identified in the cement samples. This observation could indicate that cement is one of the sources of minerals in the airborne particulate matter in the Kathmandu Valley.

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Morphological study on particulate matter of Kathmandu valley

Cited by 5 publications

References 10 publications

Optical microscopic study of surface morphology and filtering efficiency of face masks

Optical microscopic study of surface morphology and filtering efficiency of face masks

Peer Review #1 of "Optical microscopic study of surface morphology and filtering efficiency of face masks (v0.2)"

Characterization of airborne dust samples collected from core areas of Kathmandu Valley

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