It started – as unpleasant revelations often do – with a late-night thought and some frantic googling.
It was 2018 and I had just moved into my first home, a one-bed flat which hadn't been renovated since it was built in the 1960s. The bathroom still contained relics of brown and yellow floral wallpaper, and the maroon carpet had long been trodden into a crusty mat. Even the estate agent had struggled to put a positive spin on its interior design.
Armed with a circular saw and an enthusiasm for DIY wildly out of step with my natural talent, I immediately set to work eradicating the "vintage" vibe. I cut worktops to size, adapted kitchen cabinets, sliced up wooden flooring, and fitted new doors. It wasn't uncommon for the whole flat to be coated in a fine sheen of wood dust.
Then one day, I came across a product online that I found, frankly, baffling: a protective suit for cutting wood. It consisted of a full helmet with a visor, sealed at the neck, and a filter unit that's attached to a belt at the waist. The headgear resembled something you'd wear to check on a patient with a highly contagious disease, or to visit another planet. Hold on, I wondered… why would anyone go to such lengths to protect themselves from wood?
As it happens, the answer is more than a little alarming. Though wood is generally an innocuous natural substance, something we have evolved alongside for millennia – the oldest wooden shelter is thought to have been built 500,000 years ago – when you turn it into a fine powder, the situation is very different.
In the US, wood dust is now classified as a Group 1 carcinogen, a substance known to cause cancer in humans. It's a proven culprit of asthma, allergic rhinitis, chronic bronchitis, lung cancer, and nasal cancer. In fact, furniture makers have a 500-fold excess risk of developing the latter.
Of course, woodworking professionals are generally made aware of these risks. In developed countries, employers have a legal responsibility to provide adequate training and protective equipment for their workers. There are set "safe limits" for exposure, and wearing space-suit style helmets is not unusual – if something goes wrong, irresponsible businesses can be sued.
For DIYers, on the other hand, the home is riddled with mysterious dangers that they may have neither the equipment nor the knowledge to deal with safely. We're used to hearing about gruesome incidents involving power tools and electricity – such as the 55-year-old who didn't notice he'd inadvertently embedded a nail in his skull until he started to feel sick – but there is also a silent, insidious risk of harm to our respiratory health.
At the same time, hands-on renovations have never been more popular. Since the beginning of the Covid-19 pandemic, home improvement companies around the globe have reported record sales, leading to the observation that it's created "a generation of DIYers". The unprecedented demand has hit supply chains, contributing to well-documented shortages of basic construction materials such as cement and plaster and eye-watering price hikes. So what are the hidden risks of DIY? And what can we do to shield ourselves from them?
First up, there's asbestos – that fibrous, silicate material so esteemed by builders in the 1940s, 50s and 60s, who valued it for its impressive strength and potent fireproofing qualities. It was added to a vast array of products, from pipe insulation to roofing, and as a result, it can be extremely difficult to identify.
"While we no longer use very much of it, in the past around 4,000-5,000 products contained asbestos," says Arthur Frank, a professor of environmental and occupational health at Drexel University, in Philadelphia, Pennsylvania. "There's the obvious ones – building materials, roofing shingles, things like that, but many people don't realise that it's also in many plastic materials such as bowling balls and ironing board covers."
Unfortunately, even tiny quantities are potentially lethal. Asbestos is a leading cause of several harrowing conditions, including asbestosis, lung cancer and mesothelioma. "What people don't realise is that as little as one day of exposure to both humans and animals have given rise to a small number of cases of mesothelioma. And so it is a very powerful carcinogen," says Frank.
Though the sale of asbestos was widely banned in the 1990s, it lingers on in houses across the globe to this day – often hiding in unexpected places and posing as more innocuous substances. In many cases, asbestos-containing materials look identical to those without it, such as "popcorn" ceilings – texturised coatings that were fashionable in the mid- to late 20th Century as a way of concealing imperfections and muffling sound.
For years, the vast majority of asbestos-related disease was generally seen in men who had worked with the material for decades. But that is changing. Today there are a growing number of cases among DIYers, who some experts believe will be responsible for a "third wave" of asbestos deaths.
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Most of the research into DIY-related asbestos diseases comes from Australia, where asbestos was widely used in the post-war period. There were several mines across the country, including at the famous village of Wittenoom in Western Australia, where the deadliest type of the material was extracted until it was shut down in 1966.
The entire community around the mine has since been decommissioned, after more than 2,000 people in the area succumbed to asbestos-related illnesses. Many of them were children at the time they were exposed – disconcerting pictures from the era show them playing in sandpits of asbestos dust. (This was not uncommon – my own dad fondly remembers making shelters from abandoned asbestos sheets near his childhood home in one of the rougher parts of Scotland. In the summer, local children would crumble it to make asbestos "snow").
Exposure to asbestos during DIY projects in Australia is now a serious public health concern. In one 2013 survey of 3,612 people in New South Wales, 61.4% of those who said they had engaged in DIY projects reported being exposed to asbestos during these activities. Meanwhile an earlier study (from 2011) found that cases among this demographic were increasing, and accounted for 8.4% of all men and 35.7% of all women diagnosed with mesothelioma.
"I had a case recently of a lovely lady who had renovated a house 45 years before," says Deborah Yates, a respiratory physician and conjoint associate professor of respiratory medicine at the University of New South Wales. Yates explains that the woman's husband had done most of the building work and she had assisted him by passing him asbestos sheeting and sweeping up afterwards. "Of course when you sweep up it releases the respirable fibres which then get down into your lungs. She died and he was left on his own – it's really sad," she says.
But while asbestos is now notorious even among the general public, scientists are only just beginning to understand the risks posed by newer building materials.
In 2019, scientists documented a disturbing trend among workers at factories cutting "engineered stone" in the US. At least 18 had fallen ill with silicosis, an incurable and potentially fatal disease usually caused by a build-up of silica in the lungs over many years. Two died.
The product is made from quartz aggregate held together by a resin-based glue, and has been emerging as a popular alternative to natural stone for kitchen countertops – but it contains a significantly higher proportion of crystalline silica than other materials such as granite or sandstone. When sanded, cut, ground, or drilled into, it generates vast quantities of dust, which can penetrate deep in the lungs – on X-rays, the organs are almost opaque.
Though the exact mechanism behind silicosis remains elusive, the latest evidence suggests that the immune system plays a leading role in its development – possibly by ingesting the dust and triggering an inflammatory response. Somehow, in all the chaos, it is the immune cells and the chemicals they release that may be doing the real damage, eventually leading to scarring and compromising the organs' ability to function normally.
"We've had people in their twenties who have had really severe silicosis," says Yates,. She's concerned that DIYers might also be exposed when trimming this type of worktop during installation. "It's difficult because the pace of technological change is so fast, we're using products now that we never had before," she says.
In fact, when it comes to dust, it turns out even the most basic activities can be deceptively perilous. Though wielding a drill and perhaps putting up a shelf is the ultimate in beginners' DIY, this too can threaten your respiratory health. "Power tools can create respirable dust with very, very small particles – nanoparticles actually, and they're the ones that are the biggest concern at the moment," says Yates.
Then there are the chemical hazards.
Though lead-based paint hasn't been legal for decades, it was used for thousands of years, and can still be found in old buildings – where stripping the walls can release it into the air. As the historian Pliny the Elder noticed as early as the First Century AD – at the time, it was often used to paint ships – this dust is "pernicious", to put it mildly. It can accumulate in the body over time, eventually causing irreversible damage to our brains and nervous systems.
People who have been exposed to lead dust through their work have been known to develop chronic kidney impairments, anaemia, neuropathy, and fertility issues – and there's a growing awareness among experts that members of the public may be unknowingly putting themselves at risk.
Even modern-day paints are starting to worry some experts.
Traditionally, paints have relied on volatile organic compounds (VOCs) to solidify them – as they evaporate, the wet paint dries out. Then it's possible to breathe them in. And though the noxious fumes and unpleasant, chemically smell this process creates may seem to disappear within a few hours or days, the evidence now suggests that they remain, gradually oozing into the surrounding air for years. At high concentrations, they can irritate the lungs and are thought to be involved in the development of respiratory symptoms and certain cancers. They also have environmental effects, including contributing to the formation of smog in the atmosphere.
As a result, there's an ongoing effort to limit the percentage of certain VOCs in paint and shift towards water-based formulations, which tend to contain lower quantities of these chemicals and are seen as safer. But there are still oil-based paints on the market in some parts of the US, as well as the EU and the UK.
Formaldehyde is also an issue. This colourless chemical has the distinctive smell of old museums (which historically used the chemical to preserve their specimens), and an impressive track record of nasty health consequences. Over the long term, exposure can lead to asthma-like breathing difficulties, skin irritation and is suspected to cause cancer, especially myeloid leukaemia. Unfortunately, it's also present in a number of wood products, as part of the resins used to hold them together. This includes some kinds of plywood, particleboard, engineered wood flooring, and the posterchild of DIY – MDF.
According to Terry Gordon, a professor of environmental medicine at New York University, in order to choose the best safety measures, it's important to identify which specific dangers a DIY activity is exposing you to.
For example, most dust masks don't provide protection against chemical substances – just dust. "So if it's a particle, wear a mask," he says. "If it's a gas, such as the fumes from paint, you're going to want to have ventilation." The latter might include opening the windows or – ideally – completing the task outdoors.
Choosing a mask for DIY is strikingly similar to protecting yourself from Covid-19, in that the best protection will be provided by a properly fitted N95 (though another kind is better than nothing), which can block out particles up to 0.3 micrometres across. That's around the same size as the smallest bacteria or three Covid-19 particles back-to-back (it still works on them because they're usually bound to something larger).
"The lungs are a very sensitive organ," says Gordon. As a toxicologist, he's always worrying about what he and his wife have inhaled over the course of their own DIY adventures. If in doubt, his advice is to do your research and wear a mask.
Meanwhile Yates advocates caution when using new products, which may have as-yet-undocumented health effects. "I think I'd suggest using more traditional materials, rather than fancy agents or materials which haven't had their safety properly evaluated yet," she says. She also recommends avoiding cheaper home improvement products which have been produced in countries with lower safety standards.
Another option is better labelling, but this can be challenging.
"The problem is that you can't label something as dangerous if it's already in there," says Yates. Even with asbestos, where there are regulations requiring that home sellers acknowledge the presence of the material, people are often unaware of its presence when they embark upon DIY activities.
Meanwhile, Gordon is sceptical that labelling new products in home improvement shops would work either. "In California they label so many things 'carcinogen' that people ignore it," he says.
And this would only help with products that have known or proven health effects, which can take decades to emerge. After all, the parents of children playing in asbestos pits in 1950s Wittenoom had no idea that it might kill them. Given the time lag, Yates agrees that it's worth bearing in mind the possibility that some of what we're using now will be regretted by future generations.
If you'll excuse me, I'm off to buy a wood-cutting bee-suit.
* Zaria Gorvett is a senior journalist for BBC Future. Twitter: @ZariaGorvett
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