9.2 Hazardous Chemical Agents (HCA) & the Globally Harmonized System (GHS)

1. Statutory Architecture: Regulations for Hazardous Chemical Agents 2021

Construction activities use large quantities of hazardous chemicals, including solvent-borne formwork release agents, crystalline-silica-rich concrete and masonry, epoxy coatings, sealants, polyurethane waterproofing resins and acid-based masonry cleaners. Under the Occupational Health and Safety Act, these are now regulated by the Regulations for Hazardous Chemical Agents, 2021 (HCA Regulations), Government Notice R. 280 of 29 March 2021, which repealed the Regulations for Hazardous Chemical Substances, 1995. The classification, safety data sheet, labelling and packaging provisions (regulations 13(d) and 14–14D, and the Annexure tables) took effect 18 months after promulgation. The HCA Regulations do not apply where the Lead Regulations 2001 or the Asbestos Abatement Regulations 2020 apply. A replacement set of draft HCA Regulations was published for comment in April 2024 but was not in force as at October 2026.

Three regulations do most of the work on site:

1. Assessment of Exposure (Regulation 5): The employer must assess whether employees may be exposed to hazardous chemical agents, covering the agents present, the routes of exposure (inhalation, skin, ingestion), the level and duration of exposure, and the controls needed, and repeat the assessment when work changes.
2. Air Monitoring (Regulation 6): Where the assessment shows that employees may be exposed, the employer must arrange air monitoring, and only an approved inspection authority (AIA) for occupational hygiene may carry out the measurements. Results are compared with the occupational exposure limits (OELs) in Annexure 2.
3. Medical Surveillance (Regulation 7): Employees must be under medical surveillance where they may be exposed to an agent listed in Table 4 of Annexure 2, where an identifiable disease may be related to their exposure, or where an occupational health practitioner recommends it. An initial health evaluation by an occupational health practitioner is required immediately before or within 14 days of starting work involving exposure, followed by examinations at intervals not exceeding two years or as an occupational medicine practitioner specifies.

2. The Globally Harmonized System (GHS) & 16-Section Safety Data Sheets (SANS 10234)

The HCA Regulations require hazardous chemical agents to be classified, labelled and accompanied by safety data sheets in line with the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), with SANS 10234 as the South African GHS standard. GHS replaces older national hazard symbols with standard classification criteria, labels and safety data sheets.

The 16-Section Safety Data Sheet (SDS)

Every chemical supplier and manufacturer is legally obligated to provide a compliant, 16-section Safety Data Sheet. Abbreviated trade leaflets do not meet the safety data sheet requirement. The Construction Health and Safety Manager (CHSM) must ensure that the site chemical register contains current (not older than 3 to 5 years), unredacted 16-section SDSs organized under the following mandatory statutory structure:

• Section 1: Identification: Chemical product name, manufacturer/importer details, and 24-hour emergency telephone contact number.
• Section 2: Hazard(s) Identification: Complete GHS hazard classification, GHS pictograms, signal word, hazard statements (H-statements), and precautionary statements (P-statements).
• Section 3: Composition / Information on Ingredients: Chemical names, CAS registry numbers, and concentration ranges of all hazardous components.
• Section 4: First-Aid Measures: Task-specific instructions for inhalation, skin contact, eye contact, and ingestion, highlighting acute symptoms and antidotes.
• Section 5: Firefighting Measures: Suitable extinguishing media (e.g., dry powder, alcohol-resistant foam; carbon dioxide vs water jet restrictions) and hazardous combustion byproducts.
• Section 6: Accidental Release Measures: Personal precautions, emergency isolation distances, environmental containment, and cleanup procedures.
• Section 7: Handling and Storage: Safe handling practices, engineering ventilation requirements, incompatible materials, and climatic storage constraints.
• Section 8: Exposure Controls / Personal Protection: Statutory Occupational Exposure Limits (OEL-TWA, OEL-STEL), biological exposure indices (BEIs), engineering controls, and specific PPE specifications (e.g., nitrile gloves, FFP3 respirators).
• Section 9: Physical and Chemical Properties: Appearance, flash point, vapor pressure, relative density, solubility, and explosive limits (LEL/UEL).
• Section 10: Stability and Reactivity: Chemical stability, hazardous polymerization, incompatible materials (e.g., strong oxidizers, acids), and hazardous decomposition products.
• Section 11: Toxicological Information: Acute toxicity values (LD50/LC50), skin/eye irritation, carcinogenicity, mutagenicity, and respiratory sensitization.
• Section 12: Ecological Information: Aquatic ecotoxicity, biodegradability, and bioaccumulative potential.
• Section 13: Disposal Considerations: Waste characterization, hazardous waste manifesting, and regional environmental disposal regulations (NEM:WA).
• Section 14: Transport Information: UN number, proper shipping name, transport hazard class, and packing group.
• Section 15: Regulatory Information: National occupational health, environmental, and chemical control statutory listings.
• Section 16: Other Information: Revision history, abbreviations, and key references.

GHS Labeling, Pictograms & Signal Words

All chemical containers on site—including decanted secondary containers such as sprayers or buckets—must carry clear GHS labels. Labels must display:

• Product Identifier and Chemical Name;
• GHS Hazard Pictograms: Red diamond borders enclosing specific hazard symbols (e.g., Flame for flammables, Corrosion for acids/bases, Skull and Crossbones for acute lethal toxins, Health Hazard for chronic carcinogens/mutagens/respiratory sensitizers, Exclamation Mark for irritants);
• Signal Words: "DANGER" indicates severe hazard categories (e.g., fatal if swallowed, causes severe skin burns); "WARNING" indicates less severe hazard categories (e.g., harmful if swallowed, causes skin irritation);
• Hazard Statements (H-Statements): Standardized phrases describing nature and severity (e.g., H350: "May cause cancer", H314: "Causes severe skin burns and eye damage");
• Precautionary Statements (P-Statements): Standardized phrases advising prevention, response, storage, and disposal (e.g., P280: "Wear protective gloves/protective clothing/eye protection/face protection").

3. Occupational Exposure Limits (OELs) & Monitoring Methodologies

Occupational exposure limits are the airborne concentrations against which exposure is judged. Annexure 2 of the HCA Regulations lists, for each agent, an 8-hour time-weighted average limit and, where set, a short-term (STEL) or ceiling (C) limit. Most limits are based on the US ACGIH threshold limit values, and where no OEL is prescribed the employer must still reduce exposure as far as reasonably practicable. The three types are:

• OEL-TWA (Time-Weighted Average): The statutory average airborne concentration calculated over an 8-hour working shift (40-hour work week). Exposures may fluctuate above and below this value, provided the time-weighted average does not exceed the statutory limit.
• OEL-STEL (Short-Term Exposure Limit): The maximum permissible airborne concentration to which workers may be exposed continuously for a 15-minute period. A STEL must not be exceeded at any time during a workday, even if the 8-hour TWA remains within limits. By the usual (ACGIH) convention, exposures at the STEL should not occur more than four times a day, with at least 60 minutes between them.
• OEL-Ceiling (OEL-C): The absolute maximum concentration that must never be exceeded at any instant during any part of the working day. Ceiling limits are enforced for rapidly acting, acutely destructive substances (such as chlorine gas or hydrogen sulfide).

Occupational hygiene sampling conducted by the AIA involves attaching calibrated personal sampling pumps with cyclone heads or filter cassettes within the worker's breathing zone (a 300 mm hemisphere around the nose and mouth). Samples are analyzed in SANAS-accredited laboratories using certified international methodologies (such as NIOSH or MDHS).

4. Major Airborne Chemical Hazards in South African Construction

Respirable Crystalline Silica (RCS)

Respirable Crystalline Silica represents the most devastating chronic pulmonary hazard on South African construction projects. Silica is liberated during dry diamond sawing of cured concrete, concrete chasing for services, abrasive shot-blasting, dry angle grinding of brickwork, and aggregate crushing. Respirable particles (aerodynamic diameter < 4.25 microns) bypass the upper respiratory defenses and penetrate the deep pulmonary alveoli.

• Exposure Limit: The HCA Regulations' 8-hour OEL for respirable crystalline silica (quartz) is 0.1 mg/m³, and quartz is notated as a carcinogen (IARC Group 1).
• Pathology: Causes silicosis (a progressive, irreversible, incurable pulmonary fibrosis that continues even after exposure ends), massive progressive fibrosis (PMF), chronic obstructive pulmonary disease (COPD), and drastically escalates susceptibility to active pulmonary tuberculosis (TB).
• Mandatory Engineering Controls: Under Section 8(2)(b) of the OHS Act, dry cutting or dry grinding of silica-containing materials without engineering suppression is unlawful. Contractors must implement continuous water suppression systems (direct water injection onto diamond cutting blades) or integrated Local Exhaust Ventilation (LEV) shrouds coupled to certified Class M or H vacuum extraction units equipped with HEPA filtration. FFP3 particulate respirators serve solely as residual PPE.

Lead Exposure

Encountered during demolition of older industrial structures, structural refurbishment of bridges coated with historical lead-based primer paints (red lead / lead tetroxide), and hot torch-cutting of salvage structural steel. Lead is a cumulative systemic neurotoxin and hematotoxin.

• Exposure Limit: The Lead Regulations 2001 set an occupational exposure limit for lead in air of 0.15 mg/m³ (0.10 mg/m³ for tetra-ethyl lead).
• Medical Surveillance: The Lead Regulations require medical surveillance, including blood lead monitoring, for employees significantly exposed to lead, and removal from exposure where the occupational medicine practitioner finds an unacceptable blood lead level. Check the current regulations for the action levels, because draft replacement Lead Regulations were published in 2024.

Welding Fumes

Generated during heavy structural steel fabrication, pipeline welding, and rebar joining. Involves complex mixtures of metal oxides, ozone ($O_3$), and nitrogen oxides ($NO_x$). Welding of stainless steel produces highly toxic Hexavalent Chromium (Cr VI) (carcinogenic, lung cancer risk), while welding carbon steel generates Manganese ($Mn$) fumes (causes manganism, a severe Parkinsonian neurological syndrome). Mandatory controls require on-torch extraction units, mobile LEV extraction arms, and powered air-purifying respirators (PAPR).

Volatile Solvents & Isocyanates

• Solvent Vapors: Xylene, toluene, methyl ethyl ketone (MEK), and white spirits in epoxy coatings and primers produce severe central nervous system depression, chronic toxic encephalopathy, and chemical hepatitis. They also present extreme flammable vapor explosion hazards in enclosed spaces.
• Isocyanates (MDI, TDI): Found in two-component polyurethane spray foams, liquid-applied waterproofing membranes, and structural elastomeric sealants. Isocyanates are among the most potent chemical respiratory and skin sensitizers known. Exposure can induce permanent occupational asthma at concentrations in the low parts-per-billion (ppb) range. Once sensitized, an individual will experience life-threatening bronchospasms upon encountering minute trace concentrations.

5. Chemical Storage, Secondary Containment & Segregation (CR 25 and SANS 10263)

Inadequate storage of bulk chemicals causes ground contamination, fires and dangerous reactions. Construction Regulation 25 requires, for flammable liquids on construction sites (in addition to the General Safety Regulations): use and storage that does not create a fire or explosion hazard, with effective ventilation; no smoking and conspicuous notices at entrances; adequate fire-fighting equipment near the store; only one day's quantity taken out of the store; containers kept closed and empties removed; metal containers bonded and earthed when decanting; and no flammable material such as cotton waste or rags stored with flammable liquids. Good practice for chemical stores also follows SANS 10263-1 (warehousing of dangerous goods) and municipal fire bylaws:

• Dedicated, Ventilated Storage Stores: Hazardous chemical stores must be secure, weatherproof structures constructed from non-combustible materials (masonry walls with lightweight non-combustible roofs designed for explosion venting). Stores must incorporate permanent low-level and high-level cross-ventilation louvers to prevent the accumulation of heavier-than-air solvent vapors. Electrical lighting and switches must be intrinsically safe / flameproof (certified Ex d / Ex ia) conforming to SANS 10108.
• Secondary Containment Bunding: Liquid stores should stand in an impervious bund. A widely used design rule, adopted in many client specifications, is: $\text{Mandatory Bund Volume} = \max(110\% \times V_{\text{largest}}, 25\% \times V_{\text{total}})$ The bund must hold at least 110% of the capacity of the largest single container, OR 25% of the total aggregate volume of all containers stored, whichever value is greater. The floor and internal bund walls must be lined with chemical-resistant epoxy or polyurethane sealant. Bund drainage pipes must terminate in a manual discharge valve that is kept closed and padlocked at all times. Rainwater accumulating in open bunds must be visually inspected for hydrocarbon sheens before manual draining.
• Chemical Incompatibility & Segregation: Storing incompatible chemicals together can generate toxic gases, fires or violent reactions. Typical segregation rules:
  • Acids and Bases: Hydrochloric or phosphoric acid masonry cleaners must be physically segregated from caustic soda, lime, or ammonia solutions;
  • Flammables and Oxidizers: Flammable liquids (solvents, fuels) must be separated from oxidizing agents (peroxides, chlorites) by an impermeable 2-hour fire-rated barrier wall or a minimum clearance of 5.0 metres;
  • Flammable Liquids and Compressed Gases: Acetylene and oxygen gas cylinders must never be stored inside chemical liquid bunds.

6. Site Emergency Response: Eyewash Stations & Spill Kits

Whenever corrosive, toxic, or irritant chemicals are handled, emergency containment and decontamination facilities must be established immediately adjacent to the work area:

• Emergency Eyewash & Safety Showers: General Safety Regulation 3(9) requires an eyewash fountain supplied with clean water (or a similar effective facility) at or near the workplace of any employee exposed to a potential eye injury from a biological or chemical substance or physical agent, and GSR 3(10) requires a quick-acting deluge shower where large skin exposure to a toxic, corrosive or high-risk substance is possible. The US standard ANSI Z358.1 is widely used for design: reachable within about 10 seconds of travel and able to deliver a continuous flush for 15 minutes.
• Chemical Spill Kits: Dedicated chemical spill response kits must be positioned at storage depots and mixing stations. Kits must contain:
  • Universal absorbent pads and polypropylene containment socks;
  • Specialized neutralizing agents (calcium carbonate for acid spills, sodium bisulfate for alkaline spills);
  • Non-sparking antistatic plastic shovels and stiff brooms;
  • Heavy-duty hazardous chemical waste disposal bags (minimum 250-micron polyethylene) with zip ties;
  • Chemical-resistant nitrile/butyl gloves, splash goggles, and boots.

7. Medical Surveillance, Biological Monitoring and Records (HCA Regulations 7 and 9)

Medical surveillance checks that controls are actually preventing harm. Under regulation 7 of the HCA Regulations, the initial health evaluation and periodic examinations are carried out by an occupational health practitioner (an occupational medicine practitioner or a qualified occupational health nurse), while only an occupational medicine practitioner can certify an employee unfit to work where they would be exposed. A typical programme includes:

• Baseline Medical Examination: Conducted prior to employment or initial chemical exposure. Encompasses an extensive occupational history questionnaire, clinical respiratory examination, baseline spirometry (lung function testing measuring Forced Vital Capacity [FVC] and Forced Expiratory Volume in 1 second [FEV1]), baseline audiometry, and baseline biological monitoring (e.g., blood lead level or renal function profile).
• Periodic Medical Surveillance: At intervals not exceeding two years, or as the occupational medicine practitioner specifies (many programmes use annual intervals for higher exposures). Includes periodic spirometry for silica- or isocyanate-exposed workers and biological monitoring where an index exists (for example urinary metabolites for some solvents).
• Exit Medical Examination: Good practice, and often a client requirement, when an employee leaves or is moved out of exposure. It records the worker's health status at that point, which supports any later claim for an occupational disease under COIDA and protects the employer against claims for diseases contracted elsewhere.
• Records (HCA Regulation 9): The employer must keep records of all assessments, air monitoring and medical surveillance reports; personal medical records may be made available only to an occupational health practitioner; records of assessments and air monitoring must be kept for at least 30 years; and if the employer ceases activities, the records must be forwarded by registered post to the regional director. (Noise records under the Noise Exposure Regulations 2024 must be kept for 40 years; asbestos and lead have their own rules.) Long retention matters because diseases such as silicosis and occupational cancers appear decades after exposure.

8. Statutory Comparison: Airborne Chemical Hazards & Mandatory Controls

9. Construction Health and Safety Manager Governance Mandate

The registered Construction Health and Safety Manager (CHSM) serves as the primary technical gatekeeper against chemical illness on site. The CHSM must establish a centralized site Chemical Inventory Register, verify that no chemical enters the site without an approved 16-section SDS and subcontractor Task-Based Risk Assessment, audit secondary containment bunds weekly, ensure that chemical waste manifests track hazardous sludges to licensed Class H:H landfill sites, and cross-reference medical fitness certificates against the chemical exposure roster.