Impact of Noise Reduction Management on Occupational Protection and Auditory Fatigue in Hospital Central Sterile Supply Department Staff

Abstract

Objective:

This study aimed to evaluate the impact of noise reduction management on occupational protection, auditory fatigue and physical and mental well-being in central sterile supply department (CSSD) staff.

Methods:

A retrospective analysis was performed on the clinical data of the same cohort of 40 staff members from the CSSD of Nanjing Chest Hospital, Affiliated Nanjing Brain Hospital, Nanjing Medical University, between May 2023 and June 2025. All subjects received conventional management for 12 months from May 2023 to May 2024, and the combined conventional and noise reduction management for 12 months from June 2024 to June 2025. Statistical analysis was performed using SPSS 23.0 software. The following parameters before and after noise reduction management were compared using paired t-tests: occupational protection status, auditory fatigue, quality of life (Generic Quality of Life Inventory-74 [GQOLI-74], sleep quality (Pittsburgh Sleep Quality Index [PSQI] and noise intensity levels.

Results:

After the implementation of noise reduction management, the average and maximum noise exposure levels were significantly lower than those before management (P < 0.05). In addition, significant improvements were observed across the following five evaluated dimensions: noise protection awareness, implementation of noise protection measures, environmental noise optimisation, distribution and utilisation of noise protection equipment and noise supervision (all P < 0.05). Additionally, post-implementation PSQI scores were significantly lower and pure-tone hearing threshold recovery time was notably shorter than pre-implementation levels (P < 0.05). Furthermore, scores in all domains of the GQOLI-74, namely, physical function, social function, psychological function and material life, significantly increased after noise reduction management (P < 0.05).

Conclusion:

The implementation of systematic noise reduction management in the hospital CSSD was associated with reduced environmental noise levels and improved occupational protection among staff members. These measures may contribute to the alleviation of auditory fatigue and improvement in sleep quality and overall quality of life.

Ning Wei and Xia Yuan are co-first authors. These authors contributed equally to this work.

KEY MESSAGES

• (1)Noise reduction management can effectively reduce environmental noise levels in a central sterile supply department (CSSD).
• (2)Noise reduction management can be instrumental in enhancing occupational noise protection awareness and safety behaviour in CSSD staff.
• (3)Noise reduction management contributes to the alleviation of auditory fatigue and improvement in sleep quality in CSSD staff.

Introduction

The Central Sterile Supply Department (CSSD) serves as a core unit responsible for the collection, cleaning, disinfection, sterilisation, storage and distribution of reusable medical devices, instruments and items. It plays a critical role in the prevention and control of healthcare-associated infections, and its operational quality directly impacts medical safety and patient outcomes.[1] The department is functionally organised into zones for collection and cleaning, packaging, sterilisation, storage and distribution. It is equipped with specialised devices, including water purification systems, washer disinfectors, water and air jet guns, drying cabinets, sealing machines, autoclaves, steam generators, hydrogen peroxide sterilisers, ethylene oxide sterilisers, air compressors and air disinfection units. Although these devices improve operational efficiency, they contribute to notable noise pollution. Noise intensity levels in the working environment of CSSDs often exceed the limits recommended by the World Health Organization for daytime workplaces.[2]

Noise pollution in CSSDs primarily originates from mechanical equipment, operational activities and staff-generated sounds. Chronic exposure to such noise environments exerts multifaceted adverse effects on workers’ health. Acoustically, noise can directly damage the auditory system, leading to temporary or permanent hearing loss, auditory fatigue and tinnitus. Furthermore, through mediation by the central nervous and endocrine systems, noise induces a range of non-auditory health issues, including disrupted sleep architecture, reduced sleep quality, anxiety, irritability and even cardiovascular and immune dysfunction, thereby considerably diminishing overall quality of life.[3,4] Despite these risks, occupational health protection for CSSD staff, particularly regarding noise exposure control, has been inadequately addressed. Therefore, implementing scientific and rational noise reduction management for creating a quiet working environment is crucial for safeguarding the staff’s physical and mental well-being.

Noise reduction management has been implemented in clinical settings, such as intensive care units and operating rooms, demonstrating efficacy in reducing ambient noise levels.[5] However, evidence regarding its implementation in CSSDs remains limited. To address this gap, we hypothesise that systematic noise reduction management in CSSDs can considerably reduce environmental noise intensity, alleviate auditory fatigue and improve the staff’s sleep and quality of life. We conducted a self-controlled pre-post study involving 40 CSSD staff members between May 2023 and June 2025, systematically evaluating the impact of noise reduction management on these outcomes.

MATERIALS AND METHODS

General Data

This study initially included 44 CSSD staff members in Nanjing Chest Hospital, The Affiliated Brain Hospital of Nanjing Medical University, but two were excluded because of non-standard operational practices and two because of expired certifications. A self-controlled study was conducted through retrospective analysis of clinical data from this same cohort between May 2023 and June 2025.

(1) Inclusion criteria included the following: ① formal employees of the CSSD; ② complete clinical documentation; ③ possess comprehensive professional knowledge of CSSD operational principles, standard procedures and safety protocols; ④ specialised training in medical device cleaning, disinfection and sterilisation techniques; ⑤ absence of major noise-related policy changes and equipment upgrades or personnel transfers during the study period; ⑥ fulfilment of qualification requirements, such as nursing staff must have passed the national or local central sterile supply qualification examination and hospital competency assessments and technical workers must have completed departmental training and evaluation.

(2) Exclusion criteria included the following: ① impaired cardiac, hepatic or renal function [NYHA classes III–IV, Child–Pugh grade C or laboratory-confirmed renal insufficiency]; ② women planning pregnancy, currently pregnant or lactating; ③ pre-existing ear pathologies (e.g., otitis media and tympanic membrane perforation); ④ exposure to other occupational hazards (e.g., prolonged vibration, dust and toxic gases/disinfectants); ⑤ inability to complete questionnaire assessments; ⑥ hearing impairment due to non-occupational causes (e.g., ototoxic drugs and congenital disorders) with pure-tone thresholds of >40 dB HL; ⑦ history of ear diseases or contraindications to noise exposure; ⑧ non-standard operations occurred during work; ⑨ expiration of qualification.

The study protocol complied with the Declaration of Helsinki[6] and was approved by Nanjing Chest Hospital, the Affiliated Brain Hospital of Nanjing Medical University’s medical ethics committee (No.202507017). All staff members involved in the study signed a written informed consent form.

Data Sources

Retrospective data were extracted and analysed from the following archived records of the 40 staff members: ① Hospital occupational health surveillance electronic archives: annual pure-tone audiometry reports from both management periods were obtained and used in calculating the ‘initial hearing level’ and confirming exclusion criteria. ② Hospital logistics and support department environmental monitoring records: quarterly environmental noise equivalent sound level (Leq) monitoring reports from fixed measurement points, which were prepared by a professional company during the conventional management period (May 2023–May 2024) and the noise reduction management period (June 2024–June 2025), were used in calculating the average noise intensity for each period. ③ Self-administered questionnaire: a self-designed questionnaire was used in assessing occupational protection status. ④ Standardised scales: The Pittsburgh Sleep Quality Index (PSQI) and Generic Quality of Life Inventory-74 (GQOLI-74) were administered for the evaluation sleep quality and quality of life, respectively. ⑤ Laboratory testing: Pure-tone hearing threshold recovery time was measured in a standard soundproof booth.

METHODS

Implementation of Conventional Management (May 2023 to May 2024)

(1) Personnel Management

All the CSSD staff members received training in healthcare-associated infection prevention and control. Personnel entering the CSSD were required to wear appropriate personal protective equipment (PPE) according to the specific requirements of each functional zone. Staff in the contaminated item collection area wore bouffant caps, masks and gloves; those in the instrument classification and cleaning area wore bouffant caps, masks, double gloves, fluid-resistant isolation gowns, waterproof boots and goggles or face shields; personnel in the packaging and sterilisation area wore bouffant caps, masks, gloves and dedicated shoes; staff in the sterile item unloading and distribution area wore bouffant caps, dedicated shoes and functional heat-resistant gloves. Strict hand hygiene protocols and handwashing procedures were implemented across all zones.

(2) Environmental Management

Environmental cleanliness was maintained in the CSSD. Each functional zone was disinfected using air disinfection machines four times daily, and rooms without such equipment were disinfected with ultraviolet light twice daily. Air cultures were performed quarterly in all zones. The interior was strictly divided into work areas (decontamination zone, inspection/packaging/sterilisation zone and sterile storage zone) and support areas (changing rooms, offices, on-duty rest rooms and washrooms). Physical barriers and buffer zones separated these areas, and the unidirectional flow of personnel (from clean to contaminated areas) and materials (from contaminated to clean areas) was enforced to prevent retrograde movement.

(3) Workflow Management

The processing of instruments, devices and items strictly followed the sequence: collection, classification, cleaning, disinfection, drying, inspection, packaging, sterilisation, storage and distribution (first-in, first-out principle was applied in accordance with sterilisation order). Instruments, devices and items contaminated by pathogens of unknown infectious diseases were disinfected on the basis of the pathogens’ characteristics before the conventional processing.

(4) Supervision and Monitoring

Unified management was organised under the supervision of the head nurse. Quality control team leaders from each zone conducted irregular spot checks of various operational links. The ‘Three Checks and Four Verifications’ system was strictly implemented as follows: checking upon receipt, during packaging, during storage and during issuance; and verifying the item name, sterilisation effectiveness, date and destination department. Identified deficiencies in daily management were promptly addressed and corrected.

(5) Basic Hearing Protection

Staff members were provided with rubber earplugs (3M 1270 Christmas tree type, 3M Corporation, with an average noise reduction of 20–30 dB). The standardised wearing procedure was as follows: the earplug was first rolled into a thin cylinder; the opposite hand was then passed over the head to gently pull the auricle upward and backward, fully opening the external auditory canal; the compressed earplug was promptly inserted into the ear canal, and pressure was applied to its tip for 20–60 seconds until complete expansion ensured optimal sealing. Finally, a seal check was performed to confirm the considerable attenuation of ambient noise. Usage duration: staff members were instructed to properly insert the earplugs before entering any work areas of the CSSD, maintain continuous wear throughout their shifts and remove them only after exiting the noisy environment.

Implementation of Combined Conventional and Noise Reduction Management (June 2024 to June 2025)

During this period, conventional management protocols and comprehensive noise reduction measures were implemented. The primary equipment utilised in daily operations included water purification systems, washer disinfectors, water/air jet guns, drying cabinets, sealing machines, autoclaves, steam generators, hydrogen peroxide sterilisers, ethylene oxide sterilisers, air compressors and air disinfection units. According to preliminary monitoring data from our centre, these devices generated varying noise levels during operation. High-noise equipment (such as high-pressure air guns, air compressors, washers and certain sterilisers) produced noise levels reaching 85–115 dB(A) at close range, with peak instantaneous noise (e.g., from air gun exhaust and instrument collisions) exceeding 120 dB(A).

Based on this noise profile, the following noise control measures were implemented:

(1) Awareness Campaign

Noise reduction posters (e.g., ‘Reduce Noise, Start with Me’; ‘Handle Gently, Move Quietly’) were displayed at key locations, including entrances, elevators, locker rooms and offices.

(2) Equipment Noise Control

① Maintenance: High-noise equipment in the CSSD (including washer disinfectors, water/air jet guns, air compressors, drainage pumps, water purification systems, drying cabinets, autoclaves, low-temperature plasma sterilisers and air disinfection units) was maintained quarterly through regular cleaning, lubrication and servicing. Malfunctioning or ageing equipment was promptly repaired or replaced to ensure optimal operational efficiency.

② Modification: Mufflers, acoustic enclosures (≥25 dB isolation), noise-reducing bearings and vibration-damping pads were installed on high-pressure air guns and washers. Traditional compressors were replaced with low-noise models.

(3) Standardisation of Work Behaviours

① Noise reduction training: Organise a training lecture on noise pollution and <BOXEDTEXT>protection knowledge every 6 months, highlight the key points of noise reduction management and improve the awareness of staff on noise pollution protection and management participation. Machine operators received appropriate training to understand basic operational principles and procedures, thereby reducing misuse and unnecessary noise.

② Noise management capacity building: Staff members were instructed to handle items gently, place double-layer drapes on work surfaces, avoid directly pouring instruments from baskets onto tables (instead removing them in batches) and equip carts with shock-absorbing, silent wheels to minimise collision and rolling noises. Equipment was required to be powered down after use for reduced noise propagation. Communication during operations was conducted via intercoms, and loud conversations were prohibited.

③ Scheduling of disinfection procedures: Disinfection times and cycles were rationally scheduled for reduced frequency of steriliser operation and machine-generated noise.

(4) Environmental Noise Mitigation

① Acoustic flooring, sound-absorbing ceilings and wall panels (sound absorption coefficient ≥0.8) were installed.

② Layouts were optimised to separate high- and low-noise zones. High-noise zones were equipped with soundproof doors or windows, acoustic curtains and felt wall coverings. Portable sound-absorbing barriers were deployed around noisy equipment.

(5) PPE

In addition to basic rubber earplugs, a variety of hearing protection devices, including earplugs, earmuffs and protective helmets with different models and noise reduction rating values, were supplied. The staff members were allowed to select personalised equipment based on individual ear canal anatomy, comfort and noise levels in their specific work zones. Designated personnel were assigned to provide guidance on proper selection and fitting. Based on detailed noise mapping results, hierarchical hearing protection guidelines for the CSSD were developed and implemented. Staff were required to wear noise-reducing earplugs in areas with 85–100 dB, earmuffs in areas with 100–110 dB and a combination of earplugs and earmuffs (or noise-protective helmets at extreme noise points) in areas with noise levels lower than 110 dB or during specific high-noise tasks. Hearing protection was mandatory before entering high-noise zones and was not removed during work. The correct use of hearing protection was incorporated into routine quality control inspections. A system for the cleaning, maintenance and regular replacement of protective equipment was established to ensure ongoing effectiveness. Hearing tests were conducted every 3 months. Staff showing hearing loss or contraindications to noise exposure were promptly reassigned and provided with appropriate interventions.

(6) Institutional Measures

① Noise monitoring points were established (especially in high-noise zones) for real-time surveillance. Areas exceeding limits underwent prioritised remediation.

② Clear supervisory responsibilities were defined. A coordinated noise prevention mechanism was established to ensure cross-departmental implementation.

Observation Indicators

All indicators were measured or assessed before the initiation of noise reduction management (at the end of May 2024 as baseline values) and upon its completion (at the end of June 2025).

(1) Baseline Characteristics

Data included gender, age, work experience, initial hearing level, staff composition, body mass index, marital status, educational level and workload of the CSSD.

(2) Noise Intensity

A nationally certified sound level meter (B&K Type 2245, Denmark; measurement range: 20–130 dB) was deployed using a grid-based method aligned with the CSSD layout and equipment distribution. Fixed measurement points were established using a grid-based method, in accordance with the layout of the CSSD, the distribution of equipment and the primary activity paths of the staff. Eight representative locations were selected, including beside the instrument washer in the decontamination area, at the high-pressure water gun station, next to the sealer in the inspection/packaging/sterilization area, at the double-check packaging table, in the central aisle of the sterile storage shelving area, at the sorting table in the decontamination zone, at the workstation in the inspection/packaging area and at the item distribution window. All measurement points were fixed at ear height (approximately 1.5 m). Equivalent continuous A-weighted sound pressure levels (Leq) were recorded during typical 8-hour daytime shifts. All sensors were fixed at ear height (≈1.5 m) to measure equivalent continuous A-weighted sound pressure levels (Leq). The meter was set to integrating mode with 1-second sampling intervals during typical daytime shifts (09:00–17:00), covering frequencies of 20–20 kHz and a range of 30–130 dB (A). Average and maximum noise levels were recorded over the 8-hour period. Pre- and post-management measurements strictly adhered to identical sensor placement, height, timing and instrument settings to ensure comparability.

(3) Occupational Protection Status

Occupational protection was evaluated using a self-designed questionnaire. Its development strictly followed standardised scale development procedures: a preliminary item pool covering domains, such as noise protection knowledge, attitudes, behaviours and environmental management, was made through literature review and consultation with three occupational health experts, two infection control specialists and two CSSD managers; item importance, representativeness and clarity were then rated using a two-round Delphi process, and items were revised, merged or deleted in accordance with expert feedback for the preparation of the draft questionnaire; a pilot survey was subsequently conducted in December 2023, involving 20 CSSD staff members from another hospital campus, and data analysis showed an overall Cronbach’s α of 0.895 and subscale Cronbach’s α values ranging from 0.82 to 0.88, which indicated clear structure and alignment with the theoretical framework. The final questionnaire comprises 20 items across the following five dimensions: noise protection awareness (four items), implementation of protection measures (four items), environmental noise optimisation (four items), distribution and use of protective equipment (four items) and noise supervision (4 items). Each item was rated with a five-point Likert scale, yielding a total score of 0–20 per dimension. High scores reflected good occupational protection.

(4) Sleep Quality

Sleep quality was assessed using the PSQI (Cronbach’s α = 0.895).[7] The scale comprises seven components: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances (e.g., nighttime awakenings and nocturia), use of sleep medication and daytime dysfunction. Each item is scored 0–3, yielding a total score of 0–21. Sleep quality increases with decreasing score.

(5) Auditory Fatigue

The pure-tone hearing threshold recovery time was measured for the assessment of auditory fatigue.[8] Subjects were required to avoid significant noise exposure for at least 12 hours prior to testing. The baseline hearing threshold at 4 kHz was established at 5 dB HL in a standard soundproof booth (background noise <30 dB A). Subsequently, subjects were exposed to a 10-minute octave-band noise centred at 2 kHz with an intensity of 100 dB SPL. Immediately after exposure, hearing threshold at the same frequency was retested at 5, 10, 15, 30 and 60 minutes after exposure. Testing was discontinued when the threshold consistently returned to 5 dB HL on two consecutive measurements. The time interval between the onset of noise exposure and the final measurement confirming threshold recovery was defined as the recovery time, and long recovery times indicate severe auditory fatigue.

(6) Quality of Life

The GQOLI-74 (Cronbach’s α = 0.898) was used.[9] It includes four domains, each scored 0–100: physical function, social function, psychological function and material life. The total score was calculated as a weighted sum (0–100): Total Score = (Physical Function × 0.4) + (Psychological Function × 0.3) + (Social Function × 0.2) + (Material Life × 0.1). The weighting system is based on the application research of the original scale developer in the China population.[10] High scores indicate good quality of life.

All indicators were assessed before (May 2024, as baseline) and after (June 2025) the implementation of noise reduction management.

Statistical Methods

Data analysis was performed using SPSS Statistics (Version 23.0; IBM Corp., USA). The normality of all continuous variables was assessed with the Shapiro–Wilk test. Normally distributed data were presented as mean ± standard deviation (x̄±s) and analysed using t-tests. Categorical data were expressed as frequencies (percentages). A two-tailed P-value of <0.05 was considered statistically significant.

RESULTS

Baseline Characteristics

The final analysis included 40 staff members with complete baseline data. Demographic analysis revealed a predominantly female cohort (90.00%) with a mean age of 42.25 ± 3.54 years and mean CSSD work experience of 7.56 ± 3.54 years. The mean body mass index was 24.15 ± 1.52 kg/m², and the initial hearing level averaged 31.35 ± 2.50 dB. Most participants were married (75.00%) and had attained at least high school education (75.00%). Regarding professional composition, charge nurses constituted the largest group (45.00%), followed equally by associate chief nurses and staff nurses (20.00% each). Technical workers accounted for 15.00%. The daily workload involved processing 605.00 ± 52.00 surgical instrument sets and 211.00 ± 18.00 endoscopic or precision instrument sets. Moreover, 8.00 ± 2.00 low-temperature sterilisation cycles and 3.00 ± 1.00 high-temperature sterilisation cycles were completed per working day. Detailed characteristics are presented in Table 1.

Table 1.

Baseline characteristics of the 40 study participants

Baseline characteristic		[X̄±s/n(%)]
Gender	Male	4 (10.00)
	Female	36 (90.00)
Age (years)		42.25 ± 3.54
Work experience in CSSD (years)		7.56 ± 3.54
Initial hearing level (pure-tone threshold, dB)		31.35 ± 2.50
Staff composition	Associate chief nurse	8 (20.00)
	Charge nurse	18 (45.00)
	Staff nurse	8 (20.00)
	Technical worker	6 (15.00)
Body mass index (kg/m2)		24.15 ± 1.52
Marital status	Married	30 (75.00)
	Unmarried	9 (22.50)
	Divorced	1 (2.50)
	Widowed	0 (0.00)
Education level	High school or above	30 (75.00)
	Below high school	10 (25.00)
CSSD Workload	Daily surgical instrument sets (sets)	605.48 ± 52.52
	Daily endoscopic/precision instrument sets (pieces)	211.54 ± 18.65
	Daily low-temperature Sterilisation cycles (cycles)	8.25 ± 2.12
	Daily high-temperature Sterilisation cycles (cycles)	3.50 ± 1.36

Note: CSSD, central sterile supply department.

Noise Intensity

Following noise reduction management, both the average and maximum noise exposure levels among staff were significantly lower than those before management (both P < 0.05; Table 2). This result demonstrates the efficacy of the noise reduction management in effectively mitigating environmental noise exposure.

Table 2.

Comparison of noise intensity before and after noise reduction management (dB)

Time point	n	Average noise intensity	Maximum noise intensity
Before management	40	83.35 ± 10.53	115.45 ± 12.70
After management	40	70.65 ± 8.35	98.37 ± 10.65
t		5.977	6.518
P		<0.001	<0.001

Occupational Protection Status

After the implementation of noise reduction management, scores across all five dimensions were significantly higher than those before the management (all P < 0.05; Table 3). These findings indicate that the noise reduction management strategy effectively enhanced occupational protection capacity among the staff.

Table 3.

Comparison of occupational protection before and after noise reduction management (scores)

Time point	n	Noise protection awareness	Implementation of protection measures	Environmental noise optimisation	Distribution and use of equipment	Noise supervision
Before management	40	10.01 ± 2.59	10.08 ± 2.55	10.02 ± 2.43	9.24 ± 2.56	9.24 ± 2.24
After management	40	14.99 ± 3.60	14.72 ± 3.57	14.00 ± 3.30	14.69 ± 3.21	14.87 ± 3.25
t		7.102	6.689	6.142	8.395	9.021
P		<0.001	<0.001	<0.001	<0.001	<0.001

Sleep Improvement

After implementing noise reduction management, the PSQI scores of the staff were significantly lower than those before management (P < 0.05; Table 4). This finding indicates that the noise control measures contributed to a marked improvement in subjective sleep quality.

Table 4.

Comparison of sleep improvement before and after noise reduction management (scores)

Time point	n	PSQI
Before management	40	10.56 ± 1.98
After management	40	7.07 ± 1.06
t		9.828
P		<0.001

Note: PSQI, Pittsburgh Sleep Quality Index.

Auditory Fatigue

After the implementation of noise reduction management, the pure-tone hearing threshold recovery time was significantly shorter than pre-intervention levels (P < 0.05; Table 5), indicating the effective alleviation of auditory fatigue in the staff.

Table 5.

Comparison of auditory fatigue before and after noise reduction management (min)

Time point	n	Pure-tone hearing threshold recovery time
Before management	40	43.56 ± 6.14
After management	40	35.21 ± 5.21
t		6.558
P		<0.001

Quality of Life

Following noise reduction management, scores in all domains of the GQOLI-74, including physical function, social function, psychological function and material life status, were significantly higher than those before management (all P < 0.05; Table 6). These results demonstrate that the noise reduction measures substantially improved the overall quality of life of the staff.

Table 6.

Comparison of GQOLI-74 domain scores before and after noise reduction management (scores)

Time point	n	Physical function	Social function	Psychological function	Material life	Total points
Before management	40	63.58 ± 5.28	60.50 ± 5.76	61.48 ± 5.12	62.29 ± 5.10	62.20 ± 5.69
After management	40	73.65 ± 6.32	74.36 ± 6.72	75.60 ± 6.18	72.61 ± 6.18	74.27 ± 6.54
t		7.734	9.904	11.128	8.068	8.806
P		<0.001	<0.001	<0.001	<0.001	<0.001

DISCUSSION

Inadequate performance by CSSD staff not only can trigger nosocomial iatrogenic infections but also can disrupt normal hospital operations, delaying staff treatment and reducing overall administrative efficiency.[11] Therefore, ensuring the quality and effectiveness of CSSD operations is of great importance. Currently, CSSDs pose not only considerable occupational exposure and infection risks but also serious noise hazards. Prolonged exposure to high-noise environments adversely affects the physical and mental health of staff and substantially reduces the work quality and efficiency.[12,13] Consequently, implementing targeted noise reduction management in CSSDs is essential.

Although noise-induced hearing loss is generally considered irreversible, Jiang et al.[14] demonstrated that integrated noise control measures combining engineering controls and PPE can effectively reduce noise exposure levels and thereby preserve auditory function. Similarly, Pieper et al.[15] reported that the proper use of hearing protection devices alleviates post-exposure auditory fatigue, and this effect is manifested as accelerated recovery from temporary threshold shifts. In the present study, the implementation of noise reduction management in the CSSD reduced the average noise exposure from 83.35 ± 10.53 to 70.65 ± 8.35 dB (a decrease of 12.70 dB) and shortened pure-tone hearing threshold recovery time from 43.56 ± 6.14 to 35.21 ± 5.21 minutes (a reduction of 8.35 minutes). Although no established minimal clinically important difference exists for noise intensity and hearing threshold recovery time specifically in CSSD populations, these findings indicate that effective noise reduction management in this unique high-noise healthcare environment can substantially lower noise exposure and mitigate auditory fatigue among staff. These results align consistently with previous research conclusions. The reasons are as follows: the noise in CSSDs is primarily derived from three sources, namely, mechanical equipment (e.g., aged or malfunctioning machines generating abnormal operational vibrations), operational activities (e.g., collisions between instruments during handling) and staff-generated noise (e.g., raised voices necessary for communication in a noisy environment). The noise reduction strategies applied in this study included awareness campaigns, equipment noise control, behavioural standardisation, environmental noise mitigation, provision of PPE and institutional noise management protocols. First, awareness initiatives enhanced staff awareness of noise pollution and promoted active participation in mitigation efforts, facilitating the smooth implementation of subsequent measures. Regular equipment maintenance and modifications, such as upgrading outdated machinery and installing vibration dampers, reduced noise emission at the source. Furthermore, standardising operational behaviours minimised unnecessary impact and conversational noise, collectively contributing to a reduction in average and peak noise levels. Second, environmental interventions, including rational spatial planning, installation of sound-absorbing materials and acoustic barriers, effectively interrupted noise propagation pathways. Furthermore, the provision of personal hearing protection equipment, including earplugs, earmuffs, combined earplug and earmuff sets and noise-protective helmets, effectively reduced the actual noise exposure among staff. This intervention mitigated the acute acoustic trauma load on the auditory system, alleviated auditory fatigue and reduced the risk of permanent hearing loss.

Studies have indicated that chronic exposure to noisy environments can activate the sympathetic nervous system, leading to increased secretion of stress hormones, such as adrenaline, which disrupts emotional regulation and elevates psychological and physiological stress.[16,17] Furthermore, stress activates the hypothalamic–pituitary–adrenal axis, resulting in elevated cortisol levels that inhibit melatonin production and directly delay sleep onset. Persistent stress maintains sympathetic hyperactivity and increases the secretion of adrenaline and noradrenaline, thereby accelerating heart rate and elevating blood pressure. These effects further impede the ability to fall asleep. Additionally, excessive stress heightens amygdala activity and thus causes tachycardia and muscle tension that prevent the body from entering a relaxed state, further delaying sleep initiation.[18,19,20] Sleep disturbances in turn activate the stress response system, creating a vicious cycle that continuously diminishes quality of life.[21] The results of this study demonstrated a reduction in PSQI scores from 10.56 ± 1.98 to 7.07 ± 1.06 after noise reduction management, representing a decrease of 3.49 points. Notably, a PSQI reduction of ≥3 points is generally considered clinically significant,[22] and a noise intensity reduction of ≥3 dB has been recognised in multiple studies as a perceptible improvement threshold.[23] These findings suggest that implementing noise reduction management in CSSDs effectively improves the sleep quality of the staff. Furthermore, the post-intervention elevation in occupational protection scores and GQOLI-74 scores indicate enhanced occupational noise protection practices and improved quality of life. This improvement was attributed to the quarterly training sessions on noise pollution and protection implemented within the management framework, which emphasised key aspects of noise control and effectively raised staff awareness and engagement in noise reduction initiatives. The comprehensive noise control system, encompassing real-time noise monitoring, clearly defined supervisory responsibilities and a coordinated mechanism for noise pollution prevention, ensured practical implementation of mitigation measures. These efforts collectively strengthened occupational protection capabilities, reduced harm caused by noise exposure and fostered a safer and healthier working environment. Consequently, psychological and physical stress in the staff was alleviated, and sleep outcomes improved.

This study has several limitations. First, the sample size was limited, which may have affected the reliability of the conclusions, increased error margins, reduced statistical power, limited generalisability and led to model overfitting. Future studies should expand the sample size to improve statistical robustness. Second, sleep quality was assessed solely using the self-reported PSQI, without incorporating objective measures, such as actigraphy. This approach may be subject to reporting bias. Future research should include objective indicators to quantitatively evaluate sleep parameters. Third, the single-centre pre-post study design lacked a parallel control group, and thus the potential confounding effects of temporal trends or other unmeasured external factors may not have been completely excluded. Although objective metrics were employed and environmental conditions were controlled, more rigorous designs, such as cluster randomised controlled trials or stepped-wedge designs, are needed to estimate the net effect of noise reduction management and reduce bias in the estimation. Fourth, the self-administered questionnaire for assessing the occupational protection status has not undergone extensive validation. This limitation may have affected the reliability of the data and the generalisability of the findings. Fifth, the observed improvements, though statistically significant, were not accompanied by a formal power analysis based on effect sizes. Future investigations should expand sample sizes and adopt multicentre collaborations to enhance the generalisability of the findings.

CONCLUSION

The implementation of systematic noise reduction management in the hospital CSSD was associated with reduced environmental noise levels and improved occupational protection for the staff. These measures may contribute to alleviating auditory fatigue and improving sleep quality and overall quality of life.

Availability of Data and Materials

The original contributions presented in the study are included in the article. Further inquiries can be directed to the corresponding authors.

Author Contributions

Ning Wei and Xia Yuan: Responsible for the formulation and implementation of research design, as well as data collection and processing.

LiLi Sun: Participated in research and design, mainly responsible for data analysis, and provided valuable advice for the writing of preliminary papers.

Wen Bei: Responsible for the overall conception and framework construction of the paper, and completed the final revision and proofreading of the paper.

Ethics Approval and Consent to Participate

This study has been approved by the Medical Ethics Committee of Nanjing Chest Hospital, the Affiliated Brain Hospital of Nanjing Medical University (No.202507017). All staff members involved in the study signed a written informed consent form.

Conflicts of Interest

The authors declare that there are no conflicts of interest.

Funding Statement

No.