Advisor(s)

Jonghwa Oh

Committee Member(s)

Claudiu Lungu
Jo Anne Balanay

Document Type

Thesis

Date of Award

6-18-2026

Degree Name

Master of Science in Public Health (MSPH)

School

School of Public Health

Department

Environmental Health Sciences

Abstract

Noise exposure is one of the most common occupational hazards. Transportation and mate-rial moving occupations reported exposure to noise levels that ranged from moderate (81.4%), loud (15.9%), to very loud (< 0.5%). This study aimed to assess the working noise environment of freight truck operators while completing post-trip inspection. Area noise sampling was performed while freight truck engines were in idle states. A type 2 sound level meter (SLM) was utilized to record noise levels, positioned at rear of the truck cab with the microphone towards the source at a height of 5 feet. The SLM was set up for three noise metrics: Occupational Safety and Health Administration’s (OSHA) permissible exposure limit (PEL) and Hearing Conservation (HC) action level in addition to the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV). 4 trucks were sampled and for each truck, recording duration lasted approximately 15 minutes, reflecting the time spent conducting post inspections. Data collection included the average sound level (Lavg), A-weighted equivalent continuous sound level (LAeq), and maximum A-weighted sound level (LASmax). The measurements were repeated 3 times for each truck and the data were averaged. Lavg was compared to the three respective occupa-tional exposure limits (OELs), assuming a worst-case scenario. Lavg values of each sampling round among four trucks obtained using the OSHA PEL values ranged from 45.1 to 51.4 dB(A), OSHA HC criteria ranged from 37.8 to 51.9 dB(A), and ACGIH TLV values ranged from 55.5 to 67.9 dB(A). The average LAeq of three sampling rounds of the four trucks ranged from 75.4 to 76.9 dB(A) with Truck 3 having the highest average level. The average LASmax of three sampling rounds ranged from 79.3 to 92.0 dB(A), with Truck 3 having the highest average level. Though none of Lavg averages exceeded the respective OELs, Truck 3 under the ACGIH TLV criterion had the highest Lavg at 51.6.9 dB(A), LAeq at 76.9 dB(A), as well as the highest LASmax at 92.0 dB(A). The elevated sound level may be attributed to engine turnover from automated shutoff in prolonged idle states. Further studies need be conducted to investigate other potential factors such as air-brake systems, engine/cab model and age.

Keywords

commercial freight operators;engine noise;occupational noise exposure

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