Michael has worked with concrete for 27 years. His job involves “breaking out” walls and floors, mixing concrete, injection work and drilling. These days, he suffers from chronic breathlessness, has had a cough for around three years and struggles to walk long distances. It is suspected that an emphysema-like condition called silicosis is to blame. Thanks to early-onset arthritis, he’s had both knees replaced. He’s 49.
Though it might not be obvious to the millions of people who spend their days surrounded by this apparently innocuous material, concrete costs the health – and often the lives – of thousands of construction workers every year. The chief culprit is silica dust, which hangs in the air on building sites. Without proper protection, it can, over many years in the trade, scar the lungs and lead to silicosis, which is associated with chronic wheezing, arthritis, cancer and reduced life expectancy.
“It’s like a death sentence hanging over you,” says Michael. “It affects me, it affects my family, it affects everything, you know what I mean?”
Concrete is modernity’s foundation stone: it surrounds us in bridges, motorways, tunnels, hospitals, stadiums and churches – from the Roman Pantheon, which is what God might pour if he had a concrete mixer, to Clifton Cathedral in Bristol, which looks like the ashtray where he would stub out his cigarettes.
From the roads that carry medicines to the sewage pipes that whisk away waste, from the dams that deliver drinking water on tap to the walls that provide shelter and warmth, modern life as we know it is unimaginable without concrete’s stability, durability, sterility and relative cheapness. But what impact does this ultra-hard, ultra-durable substance have on our soft human bodies?
It can certainly transform public health for the better. In 2000, Mexico’s Coahuila state launched an initiative called Piso Firme (“firm floor”), which involved pouring concrete floors for low-income households that had previously been forced to make do with dirt. The aim was to reduce hookworm disease – a parasitic infection contracted by walking barefoot on soil, where hookworm larvae burrow in through skin and wind up in the digestive tract, stunting children’s growth and affecting their schooling.
Once the new floors had been installed, children in concreted homes experienced a 78% drop in parasite infection rates, while anaemia plummeted by 80%, diarrhoea fell by half and test scores improved dramatically. By 2005, 10% of Mexico’s dirt-floor houses had made the switch to concrete. Even in the developed world its nonreactive nature makes concrete the ideal allergy-friendly floor surface, performing better for respiratory ailments than carpet, tile and floorboard, which harbour dust mites, bacteria, germs and mildew.
When it comes to negative impacts, perhaps the first thing to consider is our joints. The surfaces humanity traversed as it evolved were far more forgiving than those we now spend much of our time on. Conditions suffered by factory workers perhaps offer the clearest example of concrete’s effects on the feet, knees and hips: many manufacturing jobs involve standing for long periods on hard floor, day after day, week in, week out.
“A lot of patients come through our doors who work in heavy engineering,” says Andrew Cumming at the Royal Orthopaedic hospital (ROH) in Birmingham. “There are some large car factories around the West Midlands and the Black Country, and we get a lot of people who stand on a track, working eight-, nine-, 10-hour shifts. That’s where we see our classic heel-pain person come in. It can have a knock-on effect on other [musculoskeletal] structures, too.”
The most common complaint is plantar fasciitis, a painful inflammation of the band of tissue that runs across the bottom of the foot, connecting the heel to the toes. Cumming can prescribe stretching, steroid injections and shockwave therapy, but any treatment is unlikely to be effective without workers being allowed to sit down or take a break from the concrete. “Sometimes people have to change career,” he says.
Cumming gets referrals from two other professions that spend a lot of time walking and standing on concrete: teaching and nursing. “Anecdotally, the concrete wards and floors in hospitals could be a problem,” he says.
Health and safety advice worldwide takes it as read that concrete floors cause ailments as diverse as varicose veins, achilles tendonitis and osteoarthritis. An entire industry has grown up around anti-fatigue matting, which, it is thought, mitigates tiredness by requiring constant microadjustments in balance.
The science on the subject, however, is inconclusive. Scientists at Loughborough University found that standing for as little as 90 minutes on concrete “caused serious discomfort to the feet, legs and back of the study participants” along with stiffness of the neck and shoulders; another study showed hard floors increased the risk of plantar fasciitis at assembly plants.
But in 2002 a review of all the literature in the field found “no unequivocal support” for the effects of cumulative industrial trauma on seven conditions of the foot and ankle, including plantar fasciitis. Although it is known that concrete floors cause lameness in cattle, leading to “joint swelling and body lesions, as well as abnormalities in resting behaviour and postural changes”, more research into its effect on humans is needed.
Seeming to support the link between concrete and injury is the experience of another major group with orthopaedic problems: runners. “The contrast between treadmill runners and concrete runners is really quite marked,” says Cumming. Patient numbers swell at the ROH after Christmas, when a wave of erstwhile athletes join running clubs with new year enthusiasm.
Nick Anderson, lead marathon trainer for the England athletics team, strictly limits the number of miles his clients do on concrete. “We do see more injury issues with the road than with running on trails,” he says. “I tend to get runners to do only about 30-40% on the roads – the rest will be on trails or softer ground. Road running is important but it will speed up injury rates because it’s a hard surface.”
Anderson says it is acknowledged in the running world – from coaches to physios to the athletes themselves – that concrete wreaks havoc on the joints. “We coach people getting ready for the Olympics, and a lot of world-class athletes running big volumes do most of their weekly training off-road,” he says. “Road running’s fantastic – I’m not against it, I love it. But I’m always trying to get runners to train on a multitude of surfaces, just to reduce to stress that the body is having to deal with all the time.”
The very evenness of the surface can also present a problem. “If the road is flat, often you get what I would call overuse biomechanical injuries, because you recreate the same foot plant all the time,” says Anderson. “Ultimately, though, it all ends up in the lower back, because everything in terms of the shock and stress will transfer upwards.”
The science, again, is not conclusive. “The relationship between impact loads and concrete surfaces is conflicting,” says Toby Smith, technical lead physiotherapist at the English Institute of Sport, which provides support to the Olympic and Paralympic squads. “The literature indicates that muscle activity, running speed and technique have a greater influence on joint loads than the type of surface. In essence, it’s more about how the runner interacts with a surface rather than type of surface which influences the joint loads.”
Silica and safety
But the respiratory problems on building sites and in cities around the world remain – and there is no lack of scientific consensus about those.
Concrete is a mixture of three components: water; “aggregates” such as gravel, sand or crushed rock; and cement, which acts as a binding agent. The cement causes many issues: it is highly toxic, prompting eye, skin and respiratory tract irritation, and contains calcium oxide, corrosive to human tissue, and chromium, which can prompt severe allergic reactions.
Then there’s silica. Naturally present in the Earth’s crust in sand and quartz, this material assumes its lethal form of respirable crystalline silica (RCS) dust during heavy industrial processes like cutting, drilling, blasting and demolition. Independently of silicosis, RCS can also lead to asthma, chronic obstructive pulmonary disorder, tuberculosis and kidney disease.
Lung cancer caused by long-term dust exposure kills an average of 789 UK workers every year – or roughly 15 a week. Whereas it was previously thought that this type of cancer was caused by silicosis, silica dust itself is now recognised as a carcinogenic substance.
Prof Sir Anthony Newman Taylor of Imperial College’s National Heart and Lung Institute says: “I think there’s sufficient evidence that silica itself is carcinogenic. And if you say that, then there can be no threshold [for safe exposure].”
Since silica’s dangers came to light, the UK government’s Health and Safety Executive (HSE) has pushed construction bosses to take a tighter approach to protective equipment, launched awareness campaigns such as Go Home Healthy, and published extensive safety information online.
Despite this, many say the HSE’s stance on workplace silica is not strict enough. The UK’s current legal limit for silica exposure is 0.1mg/m³, averaged over an eight-hour shift. The US, however, recently halved its legal limit to 0.05mg/m³ after extensive lobbying by its own health and safety body, the Occupational Safety and Health Administration.
The HSE says it cannot replicate this better standard due to the costs and technical difficulties involved – even though its own literature shows that six times as many workers are at risk of silicosis over a 45-year career at 0.1mg/m³ than with 0.05mg/m³. Meanwhile, jurisdictions like Portugal and British Columbia enforce even lower limits of 0.025mg/m³ – a quarter of the UK limit. Germany has gone one step further, reclassifying silica dust as a carcinogen and minimising exposure altogether.
Meanwhile, Michael, the construction worker, paints a picture of an industry ignorant of silica’s long-term effects. “It’s only recently that they really enforced masks and things like that,” he says. “About 10 years ago they started pushing for it – but sometimes you didn’t have the equipment, so it wasn’t an option. You just had to carry on.”
He believes there are others at his firm showing the symptoms of silicosis. “Oh, there’s a good 25 of us that have been there over 25 years. And I would say most of them are good suspects of having it. And that’s just one company.”
He’s currently waiting for final confirmation that the scarring on his lungs revealed by x-rays is indeed silicosis, although he says he “already half-knows”.
Michael’s advice to younger workers? “Force the issue. Physically ask for the mask before you do anything, because if you don’t ask for it, they’ll let you crack on and use drills and grinders – because they know that in a year there’s going to be a completely different gang of workers in there.”
Guardian Concrete Week investigates the shocking impact of concrete on the modern world. Follow Guardian Cities on Twitter, Facebook and Instagram and use the hashtag #GuardianConcreteWeek to join the discussion or sign up for our weekly newsletter