Evaluating the airborne asbestos dispersion in enclosed parking lots in Iran

Our plain-English summary of Evaluating the airborne asbestos dispersion in enclosed parking lots in Iran, by N. Nasirzadeh, Y. Rasoulzadeh, D. Mahmoudi, et al (Archives of Environmental & Occupational Health, 2022).

The study

• Authors: N. Nasirzadeh, Y. Rasoulzadeh, D. Mahmoudi, H. Marioryad, M.H. Abdollahi, H. Najafian, M. Khalili
• Journal: Archives of Environmental & Occupational Health
• Published: 2022;77(6):437-445
• Read it: PubMed · Publisher

Abstract

Each time a car's brakes are used, asbestos is dispersed in the air. Breathing the air in enclosed parking lots can expose people working in these places to asbestos. This study aimed to evaluate the airborne asbestos dispersion in enclosed parking lots. In this study, 35 air samples were collected from six enclosed parking lots in Tabriz City. The samples were analyzed quantitatively by phase contrast microscopy (PCM) and qualitatively by a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray analyzer. The mean of fiber concentrations was found 0.155 ± 0.069 PCM f/cc. The SEM data demonstrated that the fibers consisted of synthetic fibers (69.57%) and asbestos (30.43%). Fiber concentrations in many enclosed parking lots in the city were higher than the threshold limit value-time weighted average of the American Conference of Governmental Industrial Hygienists and Occupational Exposure Limits of Iran. However, further investigations are needed to clarify asbestos exposure in such places.

In plain English

This study measured airborne fibers in six enclosed parking lots in Tabriz, Iran, where staff worked 12-hour shifts, rarely used respirators, and ventilation was poor or absent. The authors took 35 air samples at 1.5 metres above the ground, not on workers, for 90 minutes while vehicles moved. Fibers were counted by phase contrast microscopy (PCM), which cannot tell asbestos from other fibers, and identified by scanning electron microscopy (SEM) with X-ray analysis. The overall mean PCM fiber concentration was 0.155 f/cc (standard deviation 0.069), and most PCM concentrations were above the ACGIH asbestos limit of 0.1 f/cc. By SEM, 69.57% of fibers were synthetic vitreous fibers and 30.43% were asbestos: actinolite (13.04%) and tremolite (17.39%). No chrysotile was found, and two lots had only synthetic fibers. Parking No. 3 had the highest means. The authors concluded that fiber levels were higher than ACGIH and Iranian limits. They linked higher asbestos levels to central, high-traffic lots and said more investigation was needed. They noted the small number of samples and the use of area rather than personal samples.

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 study measuring fiber concentrations with fixed area samples, not personal samples worn by workers
• Who was studied: 35 air samples, plus 13 blank samples, from six enclosed parking lots in Tabriz, Iran, under municipal supervision. Sampling dates are not given.
• Exposure: Airborne fibers (asbestos and synthetic vitreous fibers) in parking lot air, sampled at 5 L/min for 90 minutes a day while vehicles were moving, following NIOSH method 7400
• Main results:
  • Overall mean fiber concentration across all 35 samples, counted by PCM: 0.155 plus or minus 0.069 f/cc
  • Most PCM fiber concentrations were higher than the ACGIH TLV–TWA of 0.1 f/cc for asbestos
  • Parking No. 3 had the highest mean fiber concentrations: 0.261 PCM f/cc and 6.725 SEM f/cc
  • Parking No. 2 had the lowest mean fiber concentrations: 0.117 PCM f/cc and 1.418 SEM f/cc
  • By SEM with X-ray analysis, the fibers were 69.57% synthetic vitreous fibers and 30.43% asbestos
  • The asbestos fibers were actinolite (13.04%) and tremolite (17.39%)
  • No chrysotile was found in the air samples
  • In parking lots No. 1 and No. 4, only synthetic vitreous fibers were found
  • Synthetic fiber levels in lots No. 1 and 4 (0.144 and 0.149 SEM f/cc) were below the ACGIH TLV–TWA of 1 f/cc for synthetic vitreous fibers; in the other lots they were above it
  • The authors reported higher asbestos fiber concentrations on first floors (1.098 PCM f/cc, 28.28 SEM f/cc) than on ground floors (0.53 PCM f/cc, 13.73 SEM f/cc). In Table 2 these figures correspond to parking No. 3.
  • The highest mean asbestos concentration was in central, high-traffic parking lots (No. 3 and 6)
  • Each lot had at least three employees working 12-hour shifts
  • Workers rarely used respirator masks
  • Ventilation systems worked poorly or did not exist
  • Fiber concentrations in the parking lots were higher than the ACGIH TLV–TWA and Iran's occupational exposure limits
• The authors' conclusion: The authors concluded that more investigation is needed to clarify asbestos exposure in enclosed parking lots
• Limitations the authors state:
  • The number of samples was small
  • Area samples were used instead of personal samples, which the authors state are more valid for comparison with the TLV–TWA
  • PCM, used for the fiber counts, does not distinguish asbestos from non-asbestos fibers

Topics

Medical terms in this study, explained in our Lexicon: phase contrast microscopy (PCM), Threshold Limit Value (TLV), Occupational Exposure, Asbestos Exposure.

Related studies

• Evaluation of exposure to the airborne asbestos in an asbestos cement sheet manufacturing industry in Iran — D. Panahi, H. Kakooei, et al. (2011)
• Assessment of airborne asbestos exposure at an asbestos cement sheet and pipe factory in Iran — H. Marioryad, H. Kakooei, et al. (2011)
• Spatio-seasonal variation, distribution, levels, and risk assessment of airborne asbestos concentration in the most industrial city of Iran: effect of meteorological factors — M. Kermani, A. Jonidi Jafari, et al. (2021)
• Spatio-seasonal variation of airborne asbestos concentration in urban areas of Shiraz, Iran — M.K. Fathi Fathabadi, A. Abdolahnejad, et al. (2017)
• Evaluation of exposure to the airborne asbestos in an automobile brake and clutch manufacturing industry in Iran — H. Kakooei, H. Marioryad (2010)
• Monitoring of airborne asbestos fibers in an urban ambient air of Shahryar City, Iran: levels, spatial distribution, seasonal variations, and health risk assessment — F. Taghizadeh, A.J. Jafari, et al. (2019)

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