Noise & Silica Dust Exposure Control

Table of Contents

1. Purpose & Scope
2. Legal Requirements
3. Noise Exposure Limits
4. Hearing Conservation Program
5. Audiometric Testing
6. Silica Exposure Limits
7. High-Risk Activities
8. Engineering Controls
9. PPE Selection for Noise & Silica
10. Air Monitoring
11. Health Surveillance
12. HCMI Dust Control Procedures

1. Purpose & Scope

Noise-induced hearing loss (NIHL) and silicosis are two of the most significant occupational health hazards in construction. Both are entirely preventable. This guide establishes HCMI's program for controlling noise and respirable crystalline silica (RCS) exposure on all church construction projects.

Noise exposure is cumulative and irreversible. Once hearing is damaged, it cannot be restored. Silicosis is a progressive, incurable lung disease caused by inhaling respirable crystalline silica dust. Church construction and renovation projects routinely involve concrete cutting, block sawing, grinding, tuck-pointing, and demolition — all of which generate dangerous levels of silica dust.

2. Legal Requirements

• O. Reg. 213/91 s.29.1 — requires measures and procedures to protect workers from silica dust exposure on construction projects.
• O. Reg. 381/15 (Noise) — establishes the occupational exposure limit for noise at 85 dBA (8-hour time-weighted average) and requires hearing protection when exposure exceeds this limit.
• O. Reg. 490/09 (Designated Substances) — silica is a designated substance in Ontario. Employers must assess exposure, implement controls, and provide health surveillance for workers exposed above the occupational exposure limit.
• OHSA s.25(2)(h) — employers must take every precaution reasonable in the circumstances for the protection of a worker.
• O. Reg. 833 (Control of Exposure to Biological or Chemical Agents) — establishes occupational exposure limits for chemical agents including respirable crystalline silica.

3. Noise Exposure Limits

Under O. Reg. 381/15, the Ontario noise exposure limits are:

• 85 dBA TWA (8-hour time-weighted average) — the action level. Above this, hearing protection is mandatory and a hearing conservation program must be implemented.
• 3 dB exchange rate — for every 3 dB increase above 85 dBA, the permissible exposure time is halved (e.g., 88 dBA = 4 hours, 91 dBA = 2 hours, 94 dBA = 1 hour).
• 115 dBA — maximum instantaneous continuous noise level, regardless of duration.
• 140 dBC peak — maximum impact/impulse noise level (e.g., nail guns, hammering).

Common construction noise levels for reference:

• Normal conversation: 60-65 dBA
• Circular saw: 100-110 dBA
• Concrete saw: 100-115 dBA
• Impact wrench: 95-105 dBA
• Pneumatic nail gun: 100-115 dBA (impulse)
• Concrete breaker/jackhammer: 100-115 dBA
• Angle grinder: 95-110 dBA
• Backhoe/excavator: 85-95 dBA

4. Hearing Conservation Program

HCMI's hearing conservation program includes the following elements:

1. Noise assessment: Identify tasks and areas where noise exceeds 85 dBA using sound level meters or noise dosimeters.
2. Engineering controls: Where feasible, reduce noise at the source (quieter tools, vibration dampening, equipment maintenance, barriers).
3. Administrative controls: Limit exposure time, rotate workers between noisy and quiet tasks, schedule high-noise activities when fewer workers are present.
4. Hearing protection: Provide appropriate hearing protection devices (HPDs) at no cost and ensure workers are trained in proper use.
5. Audiometric testing: Baseline and annual audiograms for workers regularly exposed above 85 dBA.
6. Training: Annual training on noise hazards, the effects of noise on hearing, the proper use and care of HPDs, and the purpose of audiometric testing.
7. Signage: Post "Hearing Protection Required" signs at the perimeter of high-noise areas.

5. Audiometric Testing

HCMI provides audiometric testing for all workers who are regularly exposed to noise levels above 85 dBA TWA:

• Baseline audiogram: Conducted within 6 months of starting work in a high-noise environment. The worker must have at least 14 hours of quiet (no noise exposure above 80 dBA) before the baseline test for accurate results.
• Annual audiogram: Compared to the baseline to detect any standard threshold shift (STS), defined as a change of 10 dB or more in the average hearing threshold at 2000, 3000, and 4000 Hz in either ear.
• Follow-up: If an STS is detected, the worker is notified within 21 days, referred for medical evaluation, refitted with hearing protection, and retested within 30 days.
• Records: Audiometric records are maintained for the duration of employment plus 20 years. Results are confidential medical records.

6. Silica Exposure Limits

Respirable crystalline silica (RCS) is found in concrete, morite, brick, block, stone, and sand — materials used on every church construction project. The Ontario OEL is:

• 0.025 mg/m³ — 8-hour TWA for respirable crystalline silica (quartz). This is approximately 25 micrograms per cubic metre of air.
• 0.05 mg/m³ — OEL for cristobalite (a polymorph of silica found in some brick and refractory materials, more toxic than quartz).

To put this in perspective, the OEL represents an amount of dust invisible to the naked eye. Visible dust clouds from concrete cutting or grinding indicate exposures many times above the OEL. If you can see a dust cloud, you need respiratory protection immediately.

7. High-Risk Activities

The following construction tasks generate significant silica dust exposure and require mandatory controls on all HCMI projects:

• Concrete cutting and sawing — slab cutting, wall sawing, core drilling. Exposures can reach 10-50 times the OEL without controls.
• Concrete grinding and scarifying — floor preparation, surface finishing. Extremely high exposures without local exhaust ventilation (LEV).
• Tuck-pointing and mortar removal — common in church renovation projects. Among the highest silica exposures in construction, up to 100 times the OEL without controls.
• Block and brick cutting — masonry saws, angle grinders with masonry wheels.
• Demolition — breaking concrete, removing masonry walls, jackhammering.
• Sweeping and clean-up — dry sweeping of concrete dust generates significant airborne silica. Use wet methods or HEPA-filtered vacuums only.
• Sandblasting (abrasive blasting) — prohibited on HCMI sites when using crystalline silica as the abrasive. Alternative media (steel shot, garnet, walnut shell) must be used.

8. Engineering Controls

The hierarchy of controls requires engineering controls before relying on PPE. HCMI mandates the following engineering controls for silica-generating tasks:

Wet Methods

• All concrete saws, masonry saws, and core drills must use integrated water suppression systems.
• Water flow must be sufficient to control visible dust at the point of cutting.
• Slurry must be contained and cleaned up. Do not allow silica-laden slurry to dry and become airborne.
• In freezing conditions where water cannot be used, LEV must be substituted.

Local Exhaust Ventilation (LEV)

• Grinders, tuck-pointing tools, and handheld saws must be equipped with dust shrouds connected to HEPA-filtered vacuum systems.
• The vacuum must provide sufficient airflow per the tool manufacturer's specifications.
• HEPA filters must be rated at 99.97% efficiency at 0.3 microns.
• Vacuum filters must be changed before airflow is visibly reduced. Filter changes must be performed with respiratory protection.

Enclosure and Isolation

• Where feasible, enclose dust-generating operations with temporary barriers and negative air pressure systems.
• Isolate silica-generating work from other trades using physical barriers and scheduling.
• Post warning signage and restrict access to silica-generating work areas.

9. PPE Selection for Noise & Silica

Hearing Protection Selection

• Select hearing protection with a Noise Reduction Rating (NRR) appropriate to the noise level. Apply the NIOSH de-rating: (NRR - 7) / 2 for earplugs to estimate real-world attenuation.
• For noise levels 85-95 dBA: foam earplugs (NRR 29+) or earmuffs (NRR 25+).
• For noise levels 95-105 dBA: well-fitted foam earplugs (NRR 30+) or high-performance earmuffs.
• For noise levels above 105 dBA: dual protection (plugs AND muffs) is mandatory.

Respiratory Protection Selection for Silica

• Half-face elastomeric respirator with P100 filters: minimum protection for silica-generating tasks when engineering controls are in place and exposure is less than 10 times the OEL (Assigned Protection Factor = 10).
• Full-face elastomeric respirator with P100 filters: when exposure may exceed 10 times the OEL, or when eye protection from dust is also needed (APF = 50).
• Powered Air-Purifying Respirator (PAPR) with HEPA filters: for extended silica exposure tasks, workers who cannot achieve a fit test with tight-fitting respirators, or when comfort is needed to ensure compliance (APF = 25-1000 depending on type).
• N95 filtering facepiece respirators are NOT acceptable for silica exposure above the OEL on HCMI sites. They provide insufficient protection for construction silica exposures.

10. Air Monitoring

HCMI conducts air monitoring for silica exposure in the following situations:

• When a new silica-generating task is introduced and exposure levels are unknown.
• When engineering controls are changed or modified.
• At minimum annually for workers performing routine silica-generating tasks.
• When requested by the JHSC or a worker.
• When directed by a Ministry of Labour inspector.

Air monitoring is conducted by a qualified occupational hygienist using personal air sampling pumps worn by the worker during the task. Samples are analyzed by an accredited laboratory using NIOSH Method 7500 (X-ray diffraction). Results are shared with the worker, the JHSC, and recorded in the HCMI exposure records.

11. Health Surveillance

Under O. Reg. 490/09 (Designated Substances), workers exposed to silica above the OEL or who perform regular silica-generating tasks must participate in a health surveillance program:

• Pre-placement medical: baseline chest X-ray and pulmonary function test (spirometry) before beginning silica-exposed work.
• Periodic surveillance: chest X-ray and spirometry every 2-3 years for workers with ongoing silica exposure, annually for workers with more than 10 years of cumulative exposure.
• Medical review: a physician experienced in occupational lung disease reviews results and advises on fitness for continued silica-exposed work.
• Records: health surveillance records are maintained for 40 years after the last exposure, as silicosis can develop decades after exposure ceases.

HCMI arranges and pays for all health surveillance. Results are confidential between the worker and the examining physician. The employer receives only a fitness-for-work determination, not the clinical details.

12. HCMI Dust Control Procedures

The following procedures are mandatory on all HCMI church construction projects:

1. Pre-task planning: Before any silica-generating task, the supervisor must complete a silica exposure control plan identifying the task, expected exposure level, engineering controls to be used, PPE required, and duration.
2. Tool requirements: All concrete saws, masonry saws, and core drills must have functioning water suppression. All grinders and tuck-pointing tools must have dust shrouds with HEPA-vacuum attachment. Tools without functioning dust controls must not be used.
3. Work area isolation: When practical, isolate silica-generating work from other trades using temporary barriers. Post "Silica Hazard — Respiratory Protection Required" signage at the perimeter.
4. Housekeeping: Clean up silica dust using wet methods or HEPA-filtered vacuums only. Never dry sweep. Never use compressed air to blow off clothing or surfaces contaminated with silica dust.
5. Decontamination: Workers performing high-exposure silica tasks should change out of contaminated clothing before breaks and at the end of the shift. Contaminated clothing should not be taken home.
6. Training: All workers who may be exposed to silica must receive silica awareness training before beginning work, covering health effects, exposure limits, controls, PPE, and symptoms to report.
7. Supervision: Supervisors must verify that dust controls are in use and functioning before allowing silica-generating work to proceed. Non-compliance results in immediate work stoppage.