3.1 Fundamental Risk Terminology: Hazards, Risks, Consequences & Tolerability

Statutory and Engineering Definitions Under South African Law

In South African occupational health and safety jurisprudence, precise technical terminology is essential for regulatory compliance and legal liability management. Under Section 1 of the Occupational Health and Safety Act (Act No. 85 of 1993) [OHS Act], statutory definitions establish the baseline duties of employers, contractors, and registered Construction Health and Safety (CHS) professionals. The Act defines a hazard as a source of or exposure to danger, danger as anything which may cause injury or damage to persons or property, and risk as the probability that injury or damage will occur.

In engineering and risk management standards harmonized under SANS/ISO 31000, a hazard is defined as an intrinsic physical condition, chemical substance, mechanical action, or operational circumstance that has the inherent potential to cause harm, human injury, occupational illness, damage to property, or environmental degradation. A hazard is an innate physical property that exists regardless of whether personnel are currently present or exposed. For example, a 10-tonne precast concrete beam suspended 15 meters above the ground by a mobile crane possesses an inherent gravitational and mass hazard. The hazard potential exists continuously by virtue of gravity and mass.

Conversely, risk is not an intrinsic physical attribute of an object, but rather a variable measure of exposure to a hazard. Under SANS/ISO 31000 and standard South African construction practice, risk is defined as the effect of uncertainty on objectives, expressed as the combination of the probability (likelihood) of an occurrence of a hazardous event and the severity of injury, illness, or damage resulting from that event. Mathematically, risk is expressed as:

$\text{Risk} = \text{Probability} \times \text{Severity}$

If the contractor establishes a rigid, barricaded exclusion zone beneath the crane swing radius where no worker is permitted to enter, the probability of a worker being struck by a falling load approaches zero, rendering the operational risk low despite the catastrophic hazard potential of the suspended mass.

Distinguishing Incidents, Accidents, Near-Misses, and Dangerous Occurrences

Construction managers and safety professionals must clearly delineate between distinct event categories to satisfy statutory recording, investigation, and reporting mandates under the OHS Act and the General Administrative Regulations (GAR):

• Incident: An unplanned, unwanted, or uncontrolled sequence of events that disrupted normal site operations and resulted in, or had the potential to result in, personal physical injury, occupational disease, equipment damage, or environmental release. In contemporary health and safety management, 'incident' is the overarching umbrella concept encompassing both actual loss events and zero-loss occurrences.
• Accident: An incident that culminated in actual physical harm—specifically personal bodily injury, medical treatment, lost time, occupational disease, or structural/property destruction. In modern South African safety management, the word 'accident' is increasingly replaced by 'injury-causing incident' because 'accident' implies an unavoidable stroke of bad luck, whereas investigative root cause analyses demonstrate that incidents stem from preventable breakdowns in supervisory oversight, procedural discipline, or engineering design.
• Near-Miss: An incident where a hazardous sequence occurred or barriers failed, but through chance, fortunate timing, or spatial clearance, no actual injury, illness, or property damage occurred. For example, a heavy scaffold coupler falls four storeys from an unguarded working platform and strikes the ground 300 mm away from a passing artisan. The potential consequence was fatal, but fortuitous positioning avoided contact. Near-misses serve as critical leading indicators. Under the Heinrich-Bird accident triangle principle, identifying and rectifying the root causes of multiple near-misses is the most effective operational defense against serious lost time injuries and site fatalities.
• Reportable Incident without Injury ("Dangerous Occurrence"): "Dangerous occurrence" is an industry label, not a term used in the OHS Act. The statutory test is Section 24(1)(c): an incident must be reported where the health or safety of any person was endangered and (i) a dangerous substance was spilled, (ii) a substance under pressure was released uncontrollably, (iii) machinery or any part of it fractured or failed, resulting in flying, falling or uncontrolled moving objects, or (iv) machinery ran out of control. A major incident (Section 24(1)(b)) is also reportable. These incidents are reported to the provincial director within seven days under General Administrative Regulation 8, whether or not anyone was hurt. Typical construction examples:
  • A crane hoist rope or boom section fails and the load falls (machinery failure, falling object).
  • A hydraulic hose on an excavator bursts and sprays oil under pressure across a work area (uncontrolled release under pressure).
  • A runaway dump truck with failed brakes careers down a haul ramp (machinery out of control).
  • A diesel bowser spill or solvent leak exposes workers (dangerous substance spilled).
  • A trench or scaffold collapse with no injury is not automatically listed in Section 24(1)(c); record and investigate it internally, and check whether it involved machinery failure or a major incident before deciding it is reportable.

Health Hazards Versus Safety Hazards: Kinetic Trauma Versus Latency

A critical responsibility of the registered CHS Manager is ensuring that the site risk assessment does not focus exclusively on visible safety hazards while overlooking insidious health hazards. These two categories differ fundamentally in their operational mechanisms, kinetics, and latency periods:

• Safety Hazards: Characterized by acute, immediate, and visible energy transfers. Mechanical, gravitational, kinetic, or electrical forces transfer to the human body in fractions of a second. Examples include falls from heights, trench wall cave-ins, arc flash burns, impalement on protruding rebar, and entanglement in unguarded concrete mixer gears. The cause-and-effect relationship is immediate, obvious, and directly observable, resulting in traumatic injuries (fractures, lacerations, amputations, or immediate death).
• Health Hazards: Characterized by chronic latency, subtle systemic or cellular degradation, and delayed onset. Exposure to chemical, biological, physical, or ergonomic agents damages bodily organs over days, months, or decades before clinical symptoms emerge. Because workers do not experience immediate pain or trauma at the instant of exposure, health hazards are frequently underestimated on construction sites. Prominent examples include respirable crystalline silica (RCS) dust generated during concrete cutting or demolition, which causes irreversible pulmonary fibrosis (silicosis) and chronic obstructive pulmonary disease (COPD); excessive acoustic energy (>85 dBA) from pneumatic rock drills causing permanent sensorineural noise-induced hearing loss (NIHL); hand-arm vibration from continuous breaker use causing vascular and neurological damage (HAVS); and ergonomic strains causing degenerative musculoskeletal disc disorders.

Hazard Categories in the Construction Environment

South African construction projects encompass seven primary hazard categories, each governed by specific statutory regulations:

The "Reasonably Practicable" Test and the ALARP Framework

A cornerstone of South African safety legislation is that an employer's statutory duty under Sections 8 and 9 of the OHS Act is qualified by the legal phrase reasonably practicable. Section 1 of the Act establishes an explicit, objective four-part legal test:

'Reasonably practicable' means practicable having regard to:

1. The severity and scope of the hazard or risk concerned: The magnitude of potential consequences (e.g. fatal injury versus minor cut) and the number of people exposed.
2. The state of knowledge reasonably available: What the industry, professional bodies, engineering institutions, and published regulations know about the hazard and the proven technical methods to eliminate or mitigate it.
3. The availability and suitability of means: Whether effective engineering controls, physical barriers, or alternative technologies exist in the South African marketplace and can be realistically deployed.
4. The cost of removing or mitigating the hazard in relation to the benefits derived: The financial and operational cost of implementing safeguards weighed against the degree of risk reduction achieved.

This test does not let a contractor choose profit over safety. The Act does not quantify the cost-benefit balance, but practitioners borrow the ALARP idea that a control can be omitted only where its cost is out of all proportion to the risk reduction. Where life-threatening hazards exist (such as excavation collapses or falls from height), cost will carry little weight if suitable protection was readily available.

This statutory test integrates directly with the engineering principle of ALARP (As Low As Reasonably Practicable), which divides risk into three distinct tolerability zones:

• Intolerable / Unacceptable Region: The risk magnitude is impermissible regardless of economic expenditure. Operations cannot commence or continue under any circumstances. Elimination or fundamental substitution is legally required.
• The ALARP / Tolerable Region: The risk is undertaken only where a substantial societal or project benefit exists, provided the risk has been reduced to the point where further risk reduction would demand an expenditure grossly disproportionate to the safety benefit gained. Rigorous procedural controls, permits to work, and daily inspections are mandatory.
• Broadly Acceptable Region: The risk level is negligible, comparable to the normal risks of everyday life. Standard operating procedures, general inductions, and basic supervision are sufficient.

Inherent Risk Versus Residual Risk: The Operational Safety Boundary

Every risk assessment conducted on a South African construction site must calculate two distinct risk levels to evaluate the efficacy of proposed controls:

• Inherent Risk (Raw or Baseline Risk): The magnitude of risk inherent in a construction activity when evaluated in the complete absence of any control measures, safeguards, procedures, or personal protective equipment. For example, manual excavation of a 2.5-meter deep trench in loose, waterlogged sandy loam carries an inherent risk characterized by a catastrophic consequence (fatal engulfment) and a high probability (imminent collapse), yielding an extreme, intolerable inherent risk score.
• Residual Risk (Post-Control Risk): The remaining operational risk that persists after all planned control measures—engineered shoring boxes, edge barriers, safe access ladders, water dewatering pumps, and appointed supervisory inspections—have been fully implemented. In the trench example, with a certified steel trench box installed and inspected daily by the appointed excavation supervisor, the consequence of soil collapse outside the box remains severe, but the probability of a worker inside the box being crushed drops to rare, yielding a tolerable residual risk score.

The cardinal rule for the CHS Manager is: No construction activity may proceed based solely on an inherent risk assessment, and no work may commence until the calculated residual risk falls strictly within the acceptable ALARP boundary.