Calculating TWA For Acetone And Toluene Exposure Levels

Calculating TWA for Acetone and Toluene Exposure Levels

Calculating TWA for Acetone and Toluene Exposure Levels

Cleaning the provided assignment, the core task is to calculate the Time-Weighted Average (TWA) exposure for workers based on personal sampling data for acetone and toluene. After calculating TWA, the assessment involves informing plant management about whether these exposure levels comply with OSHA permissible exposure limits (PELs). Specifically, the assignment requests two separate calculations: one for acetone using known sampling data, and another for toluene using specified sampling data and a provided formula. The purpose is to evaluate worker exposure levels concerning OSHA standards and provide relevant safety recommendations.

Paper For Above instruction

Occupational Safety and Health Administration (OSHA) regulates exposure limits for various chemicals to protect workers' health. The Permissible Exposure Limit (PEL) for acetone is established at 1000 ppm. In this scenario, a hygienist has sampled three different exposure periods, with varying concentrations, and needs to calculate the overall TWA to assess compliance and safety. Similarly, a second case involves calculating TWA for toluene exposure based on specific measured concentrations and durations, utilizing a weighted formula. These calculations guide the hygienist in advising plant management regarding occupational safety and regulatory adherence.

Acetone Exposure Calculation:

Given data for acetone:

- 700 ppm for 3 hours

- 1300 ppm for 2 hours

- 900 ppm for 3 hours

The TWA calculation involves summing the products of each concentration with its respective exposure duration, then dividing by the total duration:

TWA = (Ca × Ta + Cb × Tb + Cc × Tc) / (Ta + Tb + Tc)

Substituting known values:

= (700 ppm × 3 hr + 1300 ppm × 2 hr + 900 ppm × 3 hr) / (3 hr + 2 hr + 3 hr)

= (2100 + 2600 + 2700) / 8

= 7400 / 8 = 925 ppm

Interpretation: The calculated TWA for acetone is 925 ppm, which is below the OSHA PEL of 1000 ppm. This indicates compliance; however, it remains close to the limit, suggesting monitoring and control measures should continue to ensure ongoing safety.

Toluene Exposure Calculation:

The formula provided for TWA is:

TWA = CaTa + CbTb + ... + CnTn / (Ta + Tb + ... + Tn)

Using the specified data:

- 500 ppm for 1 hour

- 100 ppm for 4 hours

- 225 ppm for 3 hours

Calculations:

TWA = (500 ppm × 1 hr + 100 ppm × 4 hr + 225 ppm × 3 hr) / (1 hr + 4 hr + 3 hr)

= (500 + 400 + 675) / 8

= 1575 / 8 = 196.875 ppm

Interpretation: The TWA for toluene is approximately 197 ppm, which is below the OSHA PEL of 200 ppm, indicating acceptable exposure levels. Nevertheless, management should ensure proper ventilation and personal protective equipment to keep exposure below the permissible limit and safeguard worker health.

Conclusion:

In both cases, the calculated TWAs suggest that current exposure levels are within OSHA limits, although acetone levels are approaching the threshold. Continuous monitoring, effective ventilation, and proper PPE use are essential to maintain occupational safety and regulatory compliance. Regular assessments should be conducted to identify any emerging risks and ensure adherence to occupational health standards.

References

  • Occupational Safety and Health Administration (OSHA). (2020). Permissible Exposure Limits (PELs). Retrieved from https://www.osha.gov/
  • Nelson, R. (2019). Industrial Hygiene: A Manual of Practice. John Wiley & Sons.
  • Laflamme, N. (2021). Occupational Exposure Limits for Chemical Substances. Journal of Safety Research, 72, 107-115.
  • ASHRAE. (2018). Ventilation and Indoor Air Quality Standards. ASHRAE Journal, 60(9), 56-63.
  • Jacobsen, M. (2017). Principles of Industrial Hygiene. American Industrial Hygiene Association.
  • McKinnon, R. & Sutton, A. (2019). Chemical Exposure Assessment. Environmental Monitoring & Assessment, 191, 193.
  • EPA. (2022). Toluene - Toxicological Review and Safety Data Sheet. Environmental Protection Agency.
  • NIOSH. (2023). Pocket Guide to Chemical Hazards. National Institute for Occupational Safety and Health.
  • Hodgson, M. (2018). Risk Assessment for Industrial Chemicals. Occupational Medicine, 68(2), 107-113.
  • Sargent, M. (2020). Best Practices in Industrial Hygiene Monitoring. Safety Science, 124, 104587.

Related Assignments