Eyes, skin and radiation

The early welding manuals understood the eye hazard better than any other. The Davis-Bournonville course of 1919 devoted a lecture to the care of the eyes and required coloured glasses for welders, cutters and their helpers. P. F. Willis warned in 1917 that glasses too dark strained the eyes as badly as none at all. E. Wanamaker and H. R. Pennington explained in 1921 that the arc’s ultraviolet and infrared rays were dangerous even though they could not be seen, and that a helmet must cover the whole face because exposed skin would blister. A century later, eye injuries still head many welding shops’ injury records, as they did in the running case’s, mostly among people who were not welding at all.

This chapter explains the arc’s radiation and what it does to eyes and skin, shows how exposure falls with distance, describes filters, helmets and screens and how to choose them, and covers the other eye hazard of welding shops: flying particles from grinding, chipping and cutting.

The arc’s radiation

A welding arc emits radiation across a wide range: ultraviolet, invisible and the most damaging to the surface of the eye and to skin; intense visible light, including blue light that can damage the retina; and infrared, felt as heat, which can harm the lens of the eye over long exposure. Gas tungsten arc and gas metal arc welding of aluminium and stainless steel produce particularly intense ultraviolet. Oxy-fuel flames produce much less ultraviolet but bright visible and infrared light, which is why the early gas welding manuals emphasised glare and heat. The International Agency for Research on Cancer’s 2018 evaluation classified ultraviolet radiation from welding as carcinogenic to humans, as well as welding fume.

Arc eye

Ultraviolet radiation burns the cornea, the clear surface of the eye, causing photokeratitis, known in the trade as arc eye or welder’s flash. Its cruel feature is the delay: there is no pain at the time, and the symptoms appear several hours later, often at night, as a severe gritty pain, watering, sensitivity to light and difficulty opening the eyes. It usually heals in a day or two, but it is very painful, and repeated episodes may cause lasting harm. Because of the delay, the person affected may not connect it with the moment of exposure, and the arc that caused it may have been someone else’s, struck without warning in the next bay. In the running case, most of the arc eye cases were fitters and labourers walking or working near unscreened welding.

Skin

Ultraviolet from the arc burns exposed skin like severe sunburn, and repeated exposure increases the risk of skin cancer. Welders protect their skin with the helmet covering the face and neck, as Wanamaker and Pennington insisted, and with clothing that covers the arms and body fully. Thin or light-coloured fabrics may let ultraviolet through; gaps at the neck, wrists and between gloves and sleeves are where welders are burned most often, by radiation and by spatter.

Light, heat and the deeper eye

Ultraviolet harms the eye’s surface; visible and infrared light reach deeper. Intense blue light from the arc can damage the retina, the light-sensitive layer at the back of the eye, and a direct look at an arc at close range without a filter can cause a burn there, a much more serious injury than arc eye because the retina does not heal in the same way. Infrared, absorbed by the lens of the eye over years of exposure, has long been associated with cataracts in glassblowers and furnace workers, and gas welders and cutters, working close to bright flames for long periods, need filters that absorb infrared as well as visible glare, as Wanamaker and Pennington’s heat-absorbing glasses were meant to. Modern welding filters cut all three bands; the hazard arises when no filter is used, or one meant for a different process.

Clothing against radiation and spatter

Figure 1Clothing for welding, checked by the coordinator

• Avoid: Fabricflame-resistant or heavy natural fibre, dark, closely woven; no synthetics that melt
• Avoid: Coveragesleeves to the wrist, collar closed, no gaps between gloves and sleeves or at the neck
• Avoid: Leathersjacket, sleeves, apron or cape for heavy spatter, overhead work and gouging
• Avoid: Gloveswelding gauntlets suited to the process; lighter gloves for gas tungsten arc work
• Avoid: Bootsleather safety boots, laces covered or slip-on, trousers worn over the boot tops
• Do: ? Conditionno holes, frayed edges, oil or grease; replaced when worn

Burns from spatter and radiation happen at the gaps: a collar left open, a cuff riding up, a trouser leg tucked into a boot so that spatter falls inside it, a pocket left open to catch sparks. Synthetic fabrics are dangerous because they melt and stick to the skin when hot metal lands on them. Oil and grease in clothing make it flammable. The coordinator’s clothing standard dealt with each, and the burns in the injury record fell as the gaps closed.

Visitors and other trades

Visitors, delivery drivers and contractors working in or near the shop need eye protection and to be kept away from unscreened welding, because they do not know that the arc they glance at will hurt them hours later. The shop’s induction for visitors and contractors covers arc eye in a sentence, issues safety glasses at the door, and routes visitors along screened walkways. Other trades working nearby, electricians and maintenance fitters, are warned when welding will start and given screens or protection.

Reflections from bright metal

Stainless steel, aluminium and freshly ground surfaces reflect ultraviolet strongly, so welding them can expose the welder’s face and neck from below and the side, and people nearby from unexpected angles. Welders on these metals wear helmets with good side and neck coverage, and screens are placed to block reflections as well as direct lines of sight.

Distance

Radiation from the arc spreads out as it travels, so its intensity falls with the square of the distance from the arc. Twice as far away means a quarter of the exposure; ten times as far, a hundredth.

Figure 2How radiation exposure from an arc falls with distance

exposure at distance d = exposure at 1 m × (1 m ÷ d)²

Assumed time to an arc eye dose at 1 m

about 30 seconds

Distances

1 m, 3 m and 10 m

1. at 3 m, exposure is (1 ÷ 3)² ≈ 1/9, so the time is about 9 × 30 = 270 seconds, 4.5 minutes
2. at 10 m, exposure is (1 ÷ 10)² = 1/100, so about 100 × 30 = 3,000 seconds, 50 minutes
3. a bystander a few metres away, glancing repeatedly at the arc over a shift, can easily receive an arc eye dose

Distance helps a great deal, but it is not enough on its own in a busy shop. A fitter working 3 m from an unscreened arc, glancing at it now and then over an hour, can accumulate a damaging dose, and reflections from light-coloured walls, bright metal and stainless steel add to it. That is why screens matter as much as distance.

Filters and helmets

The welder’s eyes are protected by a filter lens in the helmet, which absorbs almost all of the ultraviolet and infrared and reduces the visible light to a level at which the welder can see the work clearly. The filter’s darkness is given as a shade number; AS/NZS 1338.1 sets out filters for welding and the shades recommended for each process and current, and the welder chooses within that guidance.

The early manuals’ advice still holds. The Davis-Bournonville course’s rule, to shut out no more light than necessary because a welder who cannot see is handicapped, matches Willis’s warning that too dark a glass strains the eyes. Its rough test, of looking for white spots dancing before the eyes after welding, is a reminder that a filter too light lets through enough light to leave after-images; the modern answer is to follow the shade guidance and adjust within it for comfort. Wanamaker and Pennington’s insistence on uniform glass free of streaks or spots, and on a clear cover glass in front to take the spatter, describes exactly what modern helmets do with replaceable cover lenses.

Figure 3Eye and face protection for welding and allied work

	Protects against	Notes
Fixed-shade welding helmet	radiation, spatter, heat to the face	must be flipped up to see between welds
Auto-darkening welding helmet	radiation; darkens in a fraction of a second when the arc strikes	lets the welder see the work with the helmet down; reduces flipping and neck strain
Gas welding goggles or spectacles	glare and infrared of the flame; some flying particles	for oxy-fuel work, not arc welding
Safety glasses	flying particles	worn under the helmet and by everyone on the floor
Face shield	flying particles and sparks to the whole face	over safety glasses for grinding and chipping

Auto-darkening helmets, whose filters switch from a light shade to the welding shade in a fraction of a second when the arc strikes, have changed welding practice. The welder can position the torch and see the work with the helmet already down, so the arc is never struck with the eyes unprotected, and the neck jerk of flipping a helmet down hundreds of times a day disappears. They need their batteries and sensors checked regularly, their cover lenses replaced when pitted, and their switching speed, sensitivity and shade settings suited to the process and current in use.

Screens and curtains

Bystanders are protected by screening the arc from them. Welding screens and curtains, opaque or tinted to absorb ultraviolet, surround welding bays and separate them from walkways and other work; their lower edge is raised slightly off the floor for ventilation, and their height blocks the line of sight from people nearby. Walls and ceilings near welding are painted in dark, matt finishes that reflect less ultraviolet than bright white. In the running case, screens between the welding bays and the walkway, and around the tacking stations, did more to cut arc eye than any other single change.

Flying particles

The other eye hazard in welding shops is mechanical: particles of metal, slag, scale and abrasive thrown by grinding, chipping slag, wire brushing, cutting and hammering. A particle in the eye can scratch or embed in the cornea, and a hot or rusty fragment can cause an infection or a rust ring that needs removal by a doctor. These injuries happen to welders when they lift their helmets to chip or grind, and to everyone else nearby. The answer is safety glasses worn by everyone on the shop floor at all times, under the welding helmet as well, and face shields over safety glasses for grinding and chipping. The Davis-Bournonville course drew the same distinction a century ago: spectacles for light and heat, but goggles or masks where flying metal could strike the face.

Shared and personal equipment

The Davis-Bournonville course noted that goggles shared between welders should be sterilisable, an early awareness of hygiene with shared protective equipment. Modern practice is to issue welders their own helmets and glasses, fitted and adjusted to them, and to clean shared equipment, such as visitors’ glasses and face shields, between users.

First aid for eyes

Every welding shop needs eye-wash facilities near the work and people trained to use them, for particles, chemical splashes such as pickling paste, and to give first aid while medical help is found. Arc eye is treated by a doctor, who can relieve the pain and check for damage; it should not be treated by rubbing or by home remedies. Embedded particles are removed by a doctor with the right instruments, never by a well-meaning workmate with a matchstick or the corner of a rag. The coordinator set up eye-wash stations at each bay and arranged first-aid training for at least one person on each shift.

The running case: the eye programme

This is an illustration. The coordinator’s eye programme had four parts: screens round every welding and tacking station and along the walkway; safety glasses compulsory for everyone on the floor, including visitors, with prescription safety glasses provided for those who needed them; face shields over glasses for all grinding and chipping; and auto-darkening helmets for every welder, chosen with the welders and set up to the shade guidance for their main process. In the following year, eye injuries fell from an average of nearly five a year to two, both foreign bodies from grinding where face shields had not been worn.

A failure: the tack weld

This is an illustration. A fitter tacking parts together on a bench, holding them with one hand and the torch with the other, struck the arc with their helmet still up, as many do for a quick tack. That night they woke with severe pain in both eyes and could not work the next day.

One tack weld, struck at arm’s length without protection, had given an arc eye dose. The shop issued auto-darkening helmets to fitters as well as welders, so that the helmet could stay down while positioning the work, and made tacking without a lowered helmet a breach of the shop’s rules.

Exercise: screens and distance

A bystander works about 2 m from an arc, with an assumed time to an arc eye dose of about 30 seconds at 1 m, looking towards the arc for a total of about 3 minutes over a shift. What fraction of an arc eye dose do they receive? If they moved to 6 m, what would it be? What does this suggest about screens?

At 2 m, exposure is a quarter of that at 1 m, so the time to an arc eye dose is about 4 × 30 = 120 seconds. Three minutes, 180 seconds, is about 1.5 times an arc eye dose.

At 6 m, exposure is a thirty-sixth of that at 1 m, so the time to a dose is about 36 × 30 = 1,080 seconds, and 180 seconds is about 0.17 of a dose. Moving away helps a great deal, but in a busy shop people cannot always keep their distance and do not always know when an arc will strike; screens that block the line of sight protect them whatever the distance and wherever they look.