Beyond supplements — the environmental load on longevity
Healthspan isn't only about what you add (supplements) or do (exercise). It's also about what you're chronically exposed to. A growing body of evidence links everyday environmental and chemical exposures to inflammation, oxidative stress, endocrine disruption and cardiovascular and cancer risk. None of these is as powerful as diet, not smoking, exercise or sleep — but they are largely free to reduce, and they add up over decades.
How this list is ordered, and the problem with ordering it. These eighteen are sequenced by estimated impact across the UK population — roughly, how many people are exposed multiplied by how much harm it does them. That is a different axis from the evidence grade on each card, which says only how confident we can be that the effect is real.
The two disagree here, visibly, and it would be disright to hide it. Chronic noise carries a Strong grade and sits near the bottom, below a dozen items graded Emerging — because the evidence that it harms people is good, while the number of people it harms badly is smaller. Sun sits mid-list for the opposite reason: UV is an unambiguous carcinogen, but sunlight is also the thing you need, so the card argues for getting the dose right rather than avoiding it.
And within the Emerging group the ordering is a judgement, not a measurement. That is close to a tautology: Emerging means the human outcome data that would let anyone rank these against each other does not exist yet. Treat positions 5 to 18 as a rough grouping rather than a league table, and treat the grade on each card as the more reliable signal of the two.
🥫 Ultra-processed food Strong
A 2024 BMJ umbrella review of 45 meta-analyses and ~9.9 million people linked higher intake to 32 adverse outcomes, including roughly 50% higher cardiovascular death and ~21% higher all-cause mortality. A metabolic ward trial found people ate about 500 kcal a day more on an ultra-processed diet matched for calories and macronutrients.
And the category is genuinely weak — it puts wholemeal bread and baked beans in the same bin as cola. The full chapter says so, and gives you something better to use.
🌫️ Air pollution (PM2.5) Strong
A Group 1 carcinogen with no safe threshold, and the damage is mostly cardiovascular rather than respiratory. But the standard advice points at the wrong source: in the UK the largest single contributor is now domestic wood and solid fuel burning — about a fifth of emissions, more than twice road transport exhaust, and the only major source rising.
☢️ Radon gas Strong
The exposure almost nobody tests for, yet it's the second leading cause of lung cancer after smoking — the UK Health Security Agency attributes around 1,100 lung-cancer deaths a year to it. Radon is a colourless, odourless radioactive gas from the natural decay of uranium in rock and soil; it seeps up through cracks and floors and accumulates in enclosed ground-floor rooms, the more so in airtight modern homes. Levels depend heavily on local geology — parts of the South West (Cornwall, Devon), the Midlands (Northamptonshire, Derbyshire) and Wales are hotspots — and the risk multiplies sharply for smokers and ex-smokers.
🌡️ Cold housing Moderate
Probably the largest exposure on this page by total burden, and the one least likely to be thought of as an exposure at all. Cold raises blood pressure within hours and thickens the blood, which is why the winter excess in deaths is mostly cardiovascular and respiratory rather than hypothermia. England and Wales record on the order of twenty thousand excess deaths in an average winter, though the figure swings widely year to year with the weather. The Marmot review found excess winter deaths in the coldest quarter of English housing ran at close to three times the rate of the warmest quarter. The detail that shows this is about buildings rather than climate: countries with colder winters than ours record fewer excess winter deaths, not more, because their housing is built for it.
Why Moderate and not Strong: the mortality evidence is observational and ecological, and excess winter mortality is a noisy measure that depends on how the baseline is drawn. The mechanism is solid and there is trial evidence that insulating and heating homes improves health, but not randomised evidence on deaths. WHO graded the certainty for warming a cold home to 18 °C reducing cardiovascular mortality as moderate, and so does this page.
🔥 Gas hobs & nitrogen dioxide Emerging
Gas cooking burns fuel right in your kitchen, emitting nitrogen dioxide (NO₂) — a reddish-brown irritant gas — plus traces of benzene, a Group-1 carcinogen; gas appliances also leak benzene and methane even when switched off. NO₂ inflames the airways, and one analysis attributed roughly 1 in 8 cases of childhood asthma (~12%) to gas-hob use. Don't confuse NO₂ with carbon monoxide (CO): NO₂ is the chronic respiratory irritant from everyday cooking, whereas CO is a separate, odourless, colourless and potentially lethal gas produced by faulty or incompletely-burning appliances and blocked flues. Every home with any gas, oil or solid-fuel appliance should have an audible CO alarm — that's a life-safety device, not an air-quality one.
🪟 Ventilation & CO₂ build-up Emerging
Outdoor air sits around 420 ppm CO₂ and a well-ventilated room stays under ~800. But modern airtight, well-insulated homes trap it: in a closed bedroom one person easily pushes CO₂ past 1,500–2,000 ppm overnight, and two people behind a shut door and window routinely reach 3,000–5,000 ppm by morning. Most people have no idea — you can't see or smell it, you just wake up groggy.
Short term, controlled studies show sleep quality starts to suffer from around 1,000 ppm (lighter, more broken sleep, less deep sleep, more time awake, and a rise in morning cortisol — a stress signal); above ~2,600 ppm it measurably dents next-day concentration, logical reasoning and decision-making, and brings on the classic stuffy-room headache and grogginess. Long term, high overnight CO₂ is mostly a marker that the room isn't being flushed — so night after night you also rebreathe accumulated VOCs, fine particles and allergens, and lose restorative sleep. Cumulatively that feeds the same cardiometabolic, immune and cognitive pathways that chronic poor sleep drives over years (and a stuffy, unventilated room spreads airborne infections far more readily).
🩸 Microplastics & nanoplastics Emerging
That the particles are in human tissue is settled — blood, lung, placenta, brain, arterial plaque. What they do there is not. One human study links them to heart attack, stroke and death (hazard ratio 4.53), and it faces a serious published objection that the samples may have been contaminated in theatre.
The chemicals plastics carry have far better human evidence than the particles do — and conveniently, the same actions reduce both.
🍳 Non-stick pans & plastic food contact Emerging
An intact non-stick pan at normal cooking temperatures is not the problem — PTFE is inert and PFOA has been banned for years. Overheating an empty one is, above about 260 °C. The larger exposure is packaging and storage, where heat, fat and time decide how much migrates.
And the rules now differ inside the UK: the EU ban on bisphenol A in food contact applies in Northern Ireland, and Great Britain has consulted but not yet legislated.
💧 Drinking water Emerging
UK tap water is among the most heavily tested drinking water in the world, and the routine argument about it is mostly noise. What is actually worth knowing is narrower: chlorination by-products (trihalomethanes, regulated at 100 µg/L), lead where the supply pipe or the household plumbing is old — the commonest genuine problem in Britain, and one no treatment works can fix at the tap — nitrate in some agricultural areas, and PFAS, for which the UK currently has guideline tiers from the Drinking Water Inspectorate rather than a statutory limit.
Bottled water is not the safe alternative, and on one measure it is clearly worse. A 2024 study estimated ~240,000 plastic particles per litre in bottled water, about 90% of them nanoplastics. It is also less frequently tested than mains supply, stored for months, and sometimes warm. Buying it to avoid tap water trades a well-characterised, regulated exposure for a poorly characterised, largely unregulated one.
🍽️ Detergent & rinse-aid residue Emerging
Separate from the fumes you breathe while cleaning (above), this is about what's left on the things that touch your gut and skin. Dishwasher detergents and rinse aids don't fully wash away: a 2023 University of Zurich lab study (Ogulur & Akdis) found rinse-aid residue — especially alcohol ethoxylates — damaged the gut-barrier lining in cell, organoid and "gut-on-a-chip" models, mostly the residue left by commercial dishwashers that skip a final rinse. This is preliminary, mechanistic work (part of the "epithelial barrier hypothesis") — not proof it causes disease in people — but it's a plausible exposure that costs nothing to reduce. Likewise, laundry detergent and softener residues sit against your skin all day on clothing and bedding, where fragrances and surfactants are common skin-barrier irritants.
The formulations themselves vary enormously, and many conventional products carry ingredients worth avoiding: 1,4-dioxane (a probable carcinogen that contaminates ethoxylated surfactants — spot the tell-tale "-eth" names like sodium laureth sulfate); formaldehyde-releasing preservatives; methylisothiazolinone (a leading cause of allergic skin rashes, EU-restricted); quaternary ammonium "quats" in fabric softeners (respiratory irritants linked to asthma); synthetic-fragrance phthalates; and optical brighteners that deliberately leave a fluorescent residue on fabric. When the Environmental Working Group reviewed hundreds of detergents, roughly two-thirds scored poorly on ingredient safety — so the brand genuinely matters.
🛒 Food sourcing & provenance Emerging
"It's on the supermarket shelf" is not a guarantee it's clean. Front-of-pack marketing ("natural", "farm fresh", "wholesome") is loosely regulated and often meaningless; food fraud and mislabelling are real (the 2013 UK horsemeat scandal being the obvious case); and routine local-authority food inspections have fallen sharply with council budget cuts. Meanwhile the genuine exposures — pesticide residues on conventional produce and heavy metals (arsenic in rice, cadmium and lead found in some dark chocolate, mercury in large predatory fish) — accumulate quietly over a lifetime. Choosing trusted suppliers and, where affordable, organic reliably lowers your pesticide-residue load (organic eaters show much lower urinary pesticide metabolites; large cohorts such as NutriNet-Santé link higher organic intake to lower cancer rates, though that evidence is observational). Be aware, though, that organic mainly cuts pesticides — it does not automatically mean lower heavy metals, which come from soil and water, so variety still matters.
💨 Vaping & e-cigarettes Emerging
Often sold as harmless; the cardiovascular literature is consistent that it is not. The aerosol acutely impairs endothelial function, raises blood pressure and heart rate and makes platelets stickier — and nicotine-free vapes show acute vascular effects too. Probably far less harmful than smoking, so for a committed smoker switching it is a real gain; as a habit taken up by a non-smoker it is a new exposure with no upside.
☀️ Sun — get the dose right Balance
UV is the leading cause of skin cancer, so the rule that matters most is never burn. But total avoidance carries its own costs, and the target is exposure without burning rather than maximal blocking.
In the UK the sun is only strong enough to make vitamin D roughly April to September. A few short midday sessions a week on forearms and legs, stopping well before any pinkening, is plenty — darker skin needs longer. October to March, the UK advice is 10 µg (400 IU) daily.
🦴 Bone loss and fracture Strong
The exposure here is absence — of load. Bone is maintained by being stressed, and a life that never stresses it loses roughly 1–1.5% per month in the clearest natural experiment available, spaceflight. The finding that matters on Earth is that the intervention most people reach for does not work and the one almost nobody does: a 33-trial review of 51,145 adults found calcium supplements do not prevent fractures, while supervised heavy loading held bone that the control group was losing. A hip fracture in later life carries something like one-in-five mortality within a year, which is why this sits with the exposures rather than with the supplements.
🧴 Fragrance, cleaning products & cosmetics Moderate
Sprays, disinfectants and anything scented release volatile organic compounds — and the terpenes in citrus and pine scents react with indoor ozone to form formaldehyde and ultrafine particles after you have finished cleaning. Airway irritation and occupational asthma are well established; the systemic claims are not.
The products carrying the most fragrance have no cleaning function at all — plug-ins, scent boosters, fabric conditioner. And you cannot read most of it off a label: “parfum” is one word for up to two hundred compounds, and Great Britain still names 26 allergens where the EU and Northern Ireland now name about 82.
🧴 Fragrance, cosmetics & air "fresheners" Emerging
The single word "fragrance" or "parfum" on a label is a trade-secret loophole that can hide dozens of undisclosed chemicals — commonly phthalates (added to make scent linger), found across perfumes, shampoos, soaps, lotions, nail varnish and plug-in/spray air fresheners, alongside parabens and VOCs. Phthalates and parabens are endocrine disruptors — they mimic or block the body's own hormones. In adults, higher phthalate exposure has been associated in cohort studies with raised cardiovascular and all-cause mortality.
The bigger worry is developing children, including in the womb: they take in more per kilogram of body weight, put more on their hands and in their mouths, and have hormone, brain and reproductive systems passing through narrow developmental windows. Prenatal and early-life exposure to the phthalates carried in perfumes, lotions and shampoos has been linked to altered puberty timing, poorer neurodevelopment and behaviour, and reduced childhood lung function. "Natural" is no guarantee either — even lavender and tea-tree oils have shown hormone-like effects in children.
🔊 Chronic noise (especially at night) Strong
Traffic, rail and aircraft noise isn't just annoying — it's an established cardiovascular risk factor. The WHO estimates Western Europe loses at least 1.6 million healthy life-years a year to traffic noise, and large cohorts link every 10 dB of long-term road noise to roughly 9% higher cardiovascular mortality, alongside raised rates of heart disease, stroke and high blood pressure. The damage is mostly done at night: even while you sleep, noise fragments sleep, keeps stress hormones elevated, stops blood pressure dipping overnight, and drives oxidative stress and endothelial dysfunction — a single night of city-level traffic noise measurably stiffens blood vessels in healthy volunteers.
💡 Light at night & circadian disruption Emerging
Your body clock expects bright days and dark nights. Bright or blue-rich light in the evening — and any light leaking into the room while you sleep — suppresses melatonin and shifts your internal clock, delaying and degrading sleep. Chronic circadian disruption is best documented in night-shift workers, which the WHO/IARC classes as a probable human carcinogen, and is linked to metabolic syndrome, type-2 diabetes, weight gain, cardiovascular disease and mood disorders; even sleeping with low-level light (a TV, standby LEDs, street light) tracks with worse metabolic markers. Most of the hard evidence is from extreme shift work and the everyday ambient-light effects are still emerging — but the fix costs nothing.
Water filters — what each type actually removes
Filters are sold on a general impression of purity. They differ enormously in what they do, and the only useful question is which contaminant are you trying to remove.
| Type | Good for | Not for |
|---|---|---|
| Jug filter activated carbon | Chlorine taste and odour. Cheap, no plumbing | Lead, nitrate, PFAS, bacteria. And they grow bacteria themselves if left warm and unchanged — change the cartridge on schedule and keep the jug in the fridge |
| Carbon block plumbed or countertop | Chlorine, taste, and — if certified to NSF/ANSI 53 — lead, cysts and some VOCs | Nitrate, fluoride. PFAS only if the specific cartridge claims and has been tested for it |
| Ceramic candle often with a carbon core | Particulates and bacteria by pore size, plus whatever the carbon core is certified for. Long-lived and cleanable, and does not strip minerals | Dissolved contaminants the core is not rated for. Flow is slow by design |
| Reverse osmosis | The most complete option — nitrate, fluoride, PFAS, most dissolved solids | Wastes several litres per litre produced, needs plumbing and a tank, is slow, and strips minerals along with everything else |
On ceramic filters specifically, since they are the ones most often bought unbranded
- The ceramic is a clay body, and what is in it is a matter of trusting the maker. A candle with no manufacturer named, no WRAS listing, no NSF certification and no published test data gives you no way to check what the material is or what leaches from it. Counterfeits of well-known brands are sold online, and the failure is invisible — the water looks the same.
- Doulton is the established British manufacturer, made by Fairey Industrial Ceramics in Stoke-on-Trent, with WRAS approval and NSF/ANSI 42 and 53 certification on its flagship candles for chlorine, taste, particulates, lead and cysts, and NSF 401 for microplastics. If you want a ceramic filter, buying from a maker that publishes its test data is the whole point.
- But be precise about PFAS, because this is where the marketing outruns the certification. Doulton's PFAS reduction rests on independent laboratory testing to NSF protocols, not on a certification listing — and their dedicated PFAS reduction is a separate cartridge in the multi-stage systems rather than a property of the ceramic. Tested to a protocol is not the same as certified under a standard, and this site is not going to blur that.
- So if PFAS is your actual reason for filtering, choose a system certified to NSF/ANSI 53 for PFOA/PFOS or NSF/ANSI P473, or use reverse osmosis. If your reason is chlorine taste, lead in an old house, or microplastics, a certified ceramic-and-carbon candle is a sound, long-lived, low-waste choice.
- Match the filter to your water, not to the advertising. Your supplier publishes an annual water quality report by postcode, and it will tell you your hardness, nitrate, THM and lead position for free. Read that before spending anything.
Sun exposure and sunscreen, in detail
The sun card above is the summary. How much sunscreen you actually apply against how much the SPF was tested at, what the filter safety argument does and does not show, the UK regulatory position, and what to buy — are covered in full.
Bone density and fracture, in detail
The bone card above is the summary. What the spaceflight data established, what the LIFTMOR trial showed and did not show, how to read a DEXA result, and why the jaw side-effect everyone has heard of is misplaced at osteoporosis doses — are covered in full.
Plastic in food, in detail
The microplastics card above is the summary. Fifty-eight everyday situations that put plastic into food and drink — heating, drinking, storage, production — are graded individually in the safety section.
Vaping has its own guide now
The vaping card above is the one-paragraph version. What is in the aerosol, how fast dependence forms, what a bystander in the room actually breathes and what changed in UK law in 2025 are covered properly in their own topic.