Welding fume monitoring: what is measured and why

Short answer: a welding fume survey measures what welders breathe, metal by metal and gas by gas, and compares each result with its own limit. The Regulations for Hazardous Chemical Agents, 2021 set no limit for "welding fume" as such. What must be measured depends on what you weld: stainless steel adds hexavalent chromium and nickel, which are listed as carcinogens and carry maximum limits.

The regulations were published as Government Notice R. 280 in Government Gazette 44348 on 29 March 2021 and repealed the Regulations for Hazardous Chemical Substances, 1995. Their occupational exposure limit (OEL) tables in Annexure 2 took effect 18 months after promulgation. Where your exposure assessment shows that welders may be exposed, regulation 6 requires air monitoring by an approved inspection authority (AIA) at least every 24 months.

Why there is no single "welding fume" result

Welding fume is a mix of fine metal particles from the base metal, the consumable and any coating, and the arc also produces gases. Annexure 2 has no entry for welding fume, so a survey measures the components that have limits. Some are in Table 2, maximum limits, where exposure must be as low as reasonably practicable below the limit. Others are in Table 3, restricted limits, where exposure must be below the limit (regulation 10(1)). Occupational exposure limits explained covers the difference.

The limits for common fume components

Values are in mg/m³ unless shown as ppm. (R) means the respirable fraction and (I) the inhalable fraction.

• Manganese (Table 3): "inorganic compounds [as Mn]" 0,2 and "elemental" 0,04 (R), as 8-hour time-weighted averages. Manganese in mild steel fume can cause neurological symptoms similar to Parkinson's disease.

• Hexavalent chromium (Table 2): "Hexavalent chromium compounds: water-soluble compounds" 0,0004 (I), with a short-term or ceiling limit of 0,001 (I), and the notations CARC (carcinogen), RSEN (respiratory sensitiser) and SKIN (skin absorption). Welding converts chromium in stainless steel and some consumables to hexavalent chromium.

• Nickel (Table 2): "Nickel and its inorganic compounds [as Ni]", soluble and insoluble inorganic compounds: 0,1 (I) and 0,02 (R), each with the CARC notation. Stainless steel fume contains nickel.

• Iron and zinc oxides (Table 3): "Iron oxide fume [as Fe]" 10 (R); "Zinc oxide, fume" 4 (R), with a short-term or ceiling limit of 20 (R). Zinc oxide comes from hot work on galvanised steel and is the usual cause of metal fume fever.

• Gases (Table 3): ozone depends on workload: 0,1 ppm for heavy, 0,16 ppm for moderate and 0,2 ppm for light work, and 0,4 ppm for any workload of less than two hours. Nitrogen dioxide is 0,4 ppm. Some processes also produce carbon monoxide, with a limit of 50 ppm.

Chromium VI (water-soluble fume) and carbon monoxide are also listed in Table 4, the biological exposure indices, so regulation 7(1)(a) requires medical surveillance for employees who may be exposed to them.

How the samples are taken

• Personal, in the breathing zone: the welder wears a sampling pump, with the sampler behind the visor, because that is the air the welder inhales.

• Over a normal shift: samples run for most of the shift, so the result is representative of exposure (regulation 6(1)(d)).

• The right analysis for each agent: hexavalent chromium needs its own sample and method, because a total chromium result does not show how much is hexavalent. Gases are measured separately.

• Consultation first: the health and safety representative or committee must be informed, and given a reasonable opportunity to comment, before monitoring is carried out (regulation 6(1)(b)).

Controls that reduce exposure

For welding, the main controls are:

• Extraction at the source: on-torch extraction, or an extraction arm or hood kept close to the plume, with written instructions for its use and maintenance (regulation 10(2)(e)(ii) and (f)(ii)).

• Respirators as backup: where other controls are not enough, respiratory protective equipment must be capable of controlling exposure to below the OEL (regulation 11(2)(a)). Where a restricted limit would be exceeded without it, the area must be a respirator zone (regulation 8).

• Maintenance: keep extraction in good working order, with a thorough examination and test by an AIA at intervals not exceeding 24 months (regulation 12); see what the LEV examination checks.

A quick self-check

• List what each welder welds or cuts: mild, stainless or galvanised steel, or aluminium.

• If stainless steel is welded, check that your last survey measured hexavalent chromium and nickel, not only total fume or manganese.

• Check that samplers were worn behind the visor and that the survey is less than 24 months old.

• Watch a welder: is the extraction on and close enough to capture the plume?

• Confirm that welders who may be exposed to hexavalent chromium or carbon monoxide are under medical surveillance.

How Qualitas can help

Qualitas Occupational Consulting is a Department of Employment and Labour Approved Inspection Authority and a SANAS-accredited (ISO/IEC 17020) inspection body for asbestos, lead, noise and hazardous chemical agents. Our hazardous chemical agents surveys cover welding fume: personal samples in the welder's breathing zone, analysis for the metals that matter on your site, gas measurements where needed and practical controls, in a report written for management, SHEQ teams and auditors.

Where extraction is installed, our local exhaust ventilation surveys check whether it captures the fume. For intervals, see how often hazardous chemical agent monitoring must be done.

Not sure what your site needs? Start with our free Compliance Gap Analysis, request a quote, or call or WhatsApp 082 649 6599.

This article summarises the Regulations for Hazardous Chemical Agents, 2021 (Government Notice R. 280, Government Gazette 44348, 29 March 2021) for general guidance. It is not legal advice; refer to the regulations for the full requirements.

Christo de Wet is a SAIOH-registered occupational hygienist with 15 years' experience and the founder of Qualitas Occupational Consulting.