Morphological, Mineralogical, and Biochemical Characteristics of Particulate Matter in Three Size Fractions (PM10, PM2.5, and PM1) in the Urban Environment

Our plain-English summary of Morphological, Mineralogical, and Biochemical Characteristics of Particulate Matter in Three Size Fractions (PM10, PM2.5, and PM1) in the Urban Environment, by S. Ahmad, B. Zeb, A. Ditta, et al (ACS Omega, 2023).

The study

• Authors: S. Ahmad, B. Zeb, A. Ditta, K. Alam, U. Shahid, A.U. Shah, I. Ahmad, A. Alasmari, M. Sakran, M. Alqurashi
• Journal: ACS Omega
• Published: 2023;8(35):31661-31674
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Air pollution in megacities is increasing due to the dense population index, increasing vehicles, industries, and burning activities that negatively impact human health and climate. There is limited study of air pollution in many megacities of the world including Pakistan. Lahore is a megacity in Pakistan in which the continuous investigation of particulate matter is very important. Therefore, this study investigates particulate matter in three size fractions (PM1, PM2.5, and PM10) in Lahore, a polluted city in south Asia. The particulate matter was collected daily during the winter season of 2019. The average values of PM1, PM2.5, and PM10 were found to be 102.00 ± 64.03, 188.31 ± 49.21, and 279.73 ± 75.04 μg m-3, respectively. Various characterization techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX) were used. FT-IR and XRD techniques identified the minerals and compounds like quartz, peroxides, calcites and vaterite, feldspar group, kaolinite clay minerals, chrysotile, vaterite, illite, hematite, dolomite, calcite, magnesium phosphate, ammonium sulfate, calcium iron oxide, gypsum, vermiculite, CuSO4, and FeSO4. Morphology and elemental composition indicated quartz, iron, biological particles, carbonate, and carbonaceous particles. In addition, various elements like C, O, B, Mg, Si, Ca, Cl, Al, Na, K, Zn, and S were identified. Based on the elemental composition and morphology, different particles along with their percentage were found like carbonaceous- (38%), biogenic- (14%), boron-rich particle- (14%), feldspar- (10%), quartz- (9%), calcium-rich particle- (5%), chlorine-rich particle- (5%), and iron-rich particle (5%)-based. The main sources of the particulate matter included vehicular exertion, biomass consumption, resuspended dust, biological emissions, activities from construction sites, and industrial emissions near the sampling area.

© 2023 The Authors. Published by American Chemical Society.

In plain English

This study measured and characterized airborne particulate matter in Lahore, Pakistan. The authors collected air on quartz fiber filters on a university rooftop every day from December 1, 2018, to February 28, 2019. They gathered 90 samples in each of three particle size fractions (PM1, PM2.5 and PM10). Average concentrations were 102.00 (plus or minus 64.03) micrograms per cubic meter for PM1, 188.31 (plus or minus 49.21) for PM2.5, and 279.73 (plus or minus 75.04) for PM10. Samples were examined by X-ray diffraction, infrared spectroscopy and electron microscopy. X-ray diffraction peaks were matched to many minerals, including quartz, illite, hematite, calcite and chrysotile. The article does not report how much chrysotile was present or give any fiber counts. Electron microscopy found particles that the authors grouped as geogenic (soil and crustal), anthropogenic (mainly carbon-containing) and biogenic, with carbon the main element detected. The authors attributed the particles to sources including vehicles, biomass burning, resuspended dust, construction and industry. They noted that other techniques should also be used to study the particles' composition.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Air-sampling and laboratory characterization study of ambient particulate matter (no human subjects)
• Who was studied: Ambient air sampled daily on the rooftop of the Center of Excellence in Solid-State Physics, Punjab University, Lahore, Pakistan, from December 1, 2018, to February 28, 2019; 90 samples per size fraction
• Exposure: Urban ambient particulate matter in three size fractions (PM10, PM2.5, PM1); minerals identified included chrysotile among many others
• Main results:
  • PM1 ranged from 20.45 to 275.00 micrograms per cubic meter, with a mean of 102.00 plus or minus 64.03
  • PM2.5 ranged from 70.87 to 277.23 micrograms per cubic meter, with an average of 188.31 plus or minus 49.21
  • PM10 ranged from 141.90 to 485.90 micrograms per cubic meter, with an average of 279.73 plus or minus 75.04
  • X-ray diffraction identified chrysotile by a peak at 12.1 degrees (no quantity reported)
  • X-ray diffraction also identified quartz, vaterite, illite and other minerals
  • The samples showed poor crystallinity, with a crystallinity index of about 20%
  • In the PM1 sample, particle sizes ranged from 0.2 to 1.6 micrometers, with an average of 0.75 micrometers
  • SEM-EDX analysis sorted the particles into geogenic, anthropogenic and biogenic groups
  • Carbon was the major element by weight in all samples
• The authors' conclusion: The authors concluded that the main sources of the particulate matter were vehicles, biomass burning, resuspended dust, biological emissions, construction activities and nearby industrial emissions
• Limitations the authors state:
  • Minerals detected by infrared spectroscopy may not show up in X-ray diffraction because of differences in crystal structure
  • Particle sizes up to 18 micrometers in the PM10 sample may reflect particles accumulating on the filter
  • Other techniques should be used to evaluate the chemical composition of the particles and the influence of weather on them

Topics

Medical terms in this study, explained in our Lexicon: X-Ray Diffraction (XRD), Infrared Spectroscopy (IR), Scanning Electron Microscopy (SEM), Chrysotile, Hematite, Dolomite, vermiculite.

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