Baseline Silica Air Monitoring — Establishing Exposure Conditions Before Work Begins

Respirable crystalline silica (RCS) continues to be one of the most significant occupational health risks across construction, civil works, quarrying, manufacturing and remediation activities. While much attention is placed on monitoring during active high-risk work, baseline silica air monitoring plays an equally important role in understanding exposure conditions before work begins and verifying whether controls are effective.

Baseline monitoring provides a reference point — a clear picture of typical airborne silica conditions under existing site activities. This information supports risk assessment, regulatory compliance and informed decision-making before disturbance of silica-containing materials occurs. Understanding the nature of respirable crystalline silica and its health risks is fundamental to this process and forms a core component of modern respirable crystalline silica risk management.

What is Baseline Silica Air Monitoring?

Baseline silica air monitoring involves measuring airborne respirable dust and crystalline silica concentrations under normal or representative site conditions, prior to the introduction of high-risk tasks or changes in work practices.

The purpose is not simply to detect silica, but to establish a defensible exposure benchmark. This allows comparison against future monitoring results and helps determine whether planned works, material disturbance or process changes may increase exposure risk.

Baseline monitoring is commonly undertaken:

• Prior to construction or demolition works involving silica-containing materials

• Before introducing new processes, equipment or work methods

• To verify existing exposure conditions in workplaces with known silica risk

• As part of occupational hygiene risk assessments and broader workplace exposure risk assessment

• To support workplace exposure management and compliance obligations

Why Baseline Monitoring Matters

Without a baseline, it is difficult to determine whether exposure conditions are improving, stable or deteriorating. Baseline monitoring provides:

• A reference for comparison against future monitoring

• Evidence supporting exposure risk assessments

• Data to inform control measures and management strategies

• Early identification of potential airborne silica sources

• Documentation supporting regulatory compliance

In many cases, baseline monitoring reveals that low-level background exposure already exists due to surrounding activities, natural soil disturbance, material handling or nearby works. Understanding this starting point is critical before high-risk disturbance begins.

How Baseline Silica Monitoring is Undertaken

Baseline monitoring typically involves personal and/or area air sampling conducted under representative operating conditions.

Personal monitoring measures the respirable dust exposure experienced by workers, while static monitoring assesses general airborne concentrations across the site. These approaches form part of broader occupational hygiene and airborne contaminant assessment practices, similar in principle to other forms of workplace air monitoring used to evaluate airborne hazards.

Sampling is undertaken using calibrated personal air sampling pumps fitted with cyclones designed to collect the respirable fraction of airborne dust. Filters are analysed by a NATA-accredited laboratory to determine crystalline silica content.

Monitoring programs are designed based on:

• Work activities and potential dust generation

• Material types and silica content

• Site layout and environmental conditions

• Worker roles and exposure duration

• Existing or proposed control measures

Interpreting Baseline Monitoring Results

Baseline monitoring results are compared against workplace exposure standards to determine whether current exposure levels are within acceptable limits.

Importantly, baseline results do not represent worst-case exposure — they represent typical conditions prior to high-risk disturbance. Elevated baseline results may indicate:

• Existing dust generation from routine activities

• Poorly controlled handling of silica-containing materials

• Influence from nearby works or environmental sources

• Ineffective or absent dust suppression measures

These findings often inform whether additional controls, monitoring or management measures are required before higher-risk works commence. Broader indoor and workplace air quality considerations may also be relevant, particularly where airborne contaminants accumulate in enclosed or semi-enclosed environments, as discussed in indoor air quality and airborne contaminant management.

When Baseline Monitoring is Typically Required

Baseline silica air monitoring is commonly undertaken in:

• Construction and civil works involving soil, rock or concrete disturbance

• Quarrying, mining and material processing environments

• Manufacturing and fabrication involving silica-containing products

• Demolition or remediation works

• Infrastructure and tunnelling projects

• Workplaces with known or suspected silica exposure

It is particularly valuable where high-risk tasks are planned but have not yet commenced, allowing exposure conditions to be understood before disturbance occurs.

Baseline Monitoring vs Ongoing Monitoring

Baseline monitoring establishes a reference point. Ongoing monitoring evaluates exposure during active work and verifies the effectiveness of controls over time.

Together, they form part of a comprehensive occupational hygiene approach to managing respirable crystalline silica risk.

Supporting Workplace Silica Risk Management

Effective silica risk management requires more than a single monitoring event. Baseline monitoring is typically integrated into a broader program that may include:

• Exposure risk assessment

• Control measure implementation

• Verification monitoring

• Periodic review and reassessment

• Worker health and safety management

Baseline monitoring provides the foundation for this process by defining the starting exposure conditions within a structured occupational hygiene framework. Organisations undertaking silica-related works often engage specialist occupational hygiene services to design and implement monitoring programs tailored to site-specific conditions.

Need Support with Silica Air Monitoring?

Understanding airborne silica exposure is critical to protecting worker health and maintaining compliance. If your project involves disturbance of silica-containing materials, baseline monitoring can provide valuable insight into exposure conditions before work begins. For project-specific advice, you can contact our team to discuss monitoring requirements and risk management strategies.