RESUMEN

The PM2.5 and PM10 particles were characterized in terms of morphology (size and shape) and surface elemental composition at two different (traffic and industrial) locations in urban region of India and further linked to different morphological defining parameters. The overall PM2.5 and PM10 showed significant daily variability indicating higher PM10 as compared to PM2.5. PM2.5/PM10 ratio was found to be 0.58 ± 0.10 indicating the abundance of PM2.5. Soot aggregates, aluminosilicates, and brochosomes particles were classified based on morphology, aspect ratio (AR), and surface elemental composition of single particles. The linear regression analysis indicates the significant correlation between area equivalent (Daeq) and feret diameter (Dfd) (R2 0.86-0.98). Higher aspect ratio (1.48 ± 0.87-1.43 ± 0.50) was noted at traffic site as compared to industrial site (1.33 ± 0.58-1.29 ± 0.30), while circularity showed the opposite trend. Fractal dimension (Df) of soot aggregates estimated by the soot parameters method (SPM) were found to be 1.70, 1.72, and 1.88, mainly attributed to vehicular emissions, biomass, and industrial emission/coal burning, respectively. This further inferred that freshly emitted soot particles exhibited lacey in nature with spherical shape (Df 1.70) at traffic site, while at industrial location, they were different with compact shapes (Df 1.88) due to particle aging processes. This study inferred the synoptic changes in mass, chemical characteristics, and morphology of aerosol particles which provide the new insights into individual atmospheric particle and their dynamic nature.

Asunto(s)

RESUMEN

Historically, the atmospheric particles constitute the most primitive and recent class of air pollutants. The science of atmospheric particles erupted more than a century ago covering more than four decades of size, with past few years experiencing major advancements on both theoretic and data-based observational grounds. More recently, the plausible recognition between particulate matter (PM) and the diffusion of the COVID-19 pandemic has led to the accretion of interest in particle science. With motivation from diverse particle research interests, this paper is an 'old engineer's survey' beginning with the evolution of atmospheric particles and identifies along the way many of the global instances signaling the 'size concept' of PM. A theme that runs through the narrative is a 'previously known' generational evolution of particle science to the 'newly procured' portfolio of knowledge, with important gains on the application of unmet concepts and future approaches to PM exposure and epidemiological research.

Asunto(s)

RESUMEN

The present study deals with an evaluation of the air purifier's effectiveness in reducing the concentration of different sized particulate matter (PM) and ions in the real-world indoor environment. Two types of air purifiers (API and APII) mainly equipped with High-Efficiency Particulate Air (HEPA) filters that differed in other specifications were employed in general indoor air and the presence of an external source (candles and incense). The gravimetric sampling of PM was carried out by SKC Cascade Impactor and further samples were analyzed for determining ions' concentration while real-time monitoring of different sized PM was done through Grimm Aerosol Spectrometer (1.109). The result showed that API reduced PM levels of different sizes ranged from 12-52% and 29-53% in general indoor air and presence of external source respectively. Concerning the APII, a higher decrease percent in PM level was explored in presence of an external source (52-68%) as compared to scenarios of general indoor air (37-64%). The concentrations of the ions were noticed to be decreased in all three size fractions but surprisingly some ions' (not specific) concentrations increased on the operation of both types of air purifiers. Overall, the study recommends the use of air purifiers with mechanical filters (HEPA) instead of those which release ions for air purification.

RESUMEN

Presented here are size-resolved aerosol measurements conducted using cascade impactor set at breathing zone in indoor-outdoor residential microenvironments. PM2.5 contributed about 64-80% of PM10 in which over 29% of mass was shared by PM0.25. Total PM concentration varied from 261 ± 22 µg/m3 (indoors) to 256 ± 64 µg/m3 (outdoors) annually; whilst summer and monsoon demonstrated 1.2- and 1.9- times lower concentration than winters. The measured metals ranged between 9% (in PM2.5-10) to 18% (in PM1-2.5) of aerosol concentration; whereby crustal elements dominated coarse fractions with relatively higher proportion of toxic elements (Ba, Cd, Co, Cr, Cu, Ni) in ultrafine range. Considering lognormal particle size distribution (PSD), accumulation mode represented the main surface area during entire monitoring period (Mass Median Aerodynamic Diameter (MMAD) < 1). PSD of metal species reflected their different emission sources with respect to season integrated samples. High air exchange conditions permitted the shift of indoor PSD pattern closer to that of outdoor air while low ventilation in winters reflected modal shift of metals (Pb, Mg. K) towards larger size particles. Relative surge towards smaller diameter size of soluble metal fraction relative to the total concentration of toxic elements was noted on an annual basis with high infiltration capacity of smaller size particulates (Finf =1.36 for ultrafine particles in summers) identified through indoor-outdoor regression analysis. Principal Component Analysis identified sources such as vehicular traffic, combustion, crustal emission with activities viz. smoking and those involving use of electric appliances.

Asunto(s)

RESUMEN

Attempts have been made to comprehend size distribution pattern of Particulate Matter (PM) and associated elemental concentration within coarse (2.5-10µm), quasi-accumulation (q-Acc) (0.25-2.5µm) and quasi-ultrafine (q-UF) (<0.25µm) ranges at indoors and outdoors of residential homes of Agra. Overall, the average mass concentrations of PM10 and PM2.5 in indoors were found to be 263.24±59.24 and 212.01±38.06µgm-3 while in outdoors the concentrations accounted to 194.28±15.25 and 152.88±16.31µgm-3 respectively; exceeding WHO standards. In view of geographical variation, significantly higher (t=2.461; P=0.044) PM mass was found in outdoor samples of roadside location when compared to homes located far away from busy traffic; whereas indoor concentration exhibited non-significant relationship (t=1.887; P=0.095) between the two categorized homes. Findings of size partitioning trend through deployment of Sioutas Cascade Impactor evidenced presence of high proportion of PM and elemental concentrations within q-Acc and q-UF modes with their distribution pattern and probable emission sources conferred upon. Absence of modal peak in coarse range indicated predominance of anthropogenic emissions with presumed wash-out of coarse particles during frequent precipitation coincidental with sampling event. Seeming modal shifts for some elements (K, Cd, Zn) from q-Acc to q-UF were perceived during infiltration process. Presence of high traffic emission in homes near busy road stemmed the shifting of particles (Cu, K, Co, Zn) towards finer size (preferably q-UF mode) thus exposing residents to adverse health effects through their penetration (Finf=0.14) into indoor environment. Flat slopes (0.11) and poor correlation (8.4%) for metals in coarser range obtained through regression model hypothesized their high deposition velocities and low penetration efficiency. Our findings suggest enhanced resident exposure to fine particles (81%) especially q-UF range (37%) through indoor and outdoor (through infiltration) sources along with complexity of size distribution of airborne particles that prerequisites surplus consideration to achieve a healthier environment within residential area.

Asunto(s)