{
  "slug": "underdressed-at-home",
  "question": "What are the odds of getting sick from walking around home without a hat, scarf, gloves, socks, or slippers?",
  "category": "health",
  "no_reliable_estimate": true,
  "perceived": {
    "description": "A folk belief in much of the world holds that being under-dressed at home — bare feet on a tile floor, no slippers (\"papucie\" in Polish, \"тапочки\" in Russian, the slipper-culture common to most of Central and Eastern Europe and much of East Asia), no sweater, a draft on the neck — causes colds, flu, pneumonia, or vague \"getting sick.\" The mechanism the folk model implies is that cold exposure on the skin directly produces respiratory illness. There is no good survey of how US or global adults rate this risk numerically; what exists is a large body of ethnographic and clinical anecdote that the belief is near-universal and durable across generations, especially from parents and grandparents to children.\n",
    "rough_estimate": "Commonly framed as 'you'll catch a cold,' with no numerical estimate attached",
    "kind": "intuition"
  },
  "sources": [
    {
      "url": "https://pubmed.ncbi.nlm.nih.gov/16286463/",
      "title": "Acute cooling of the feet and the onset of common cold symptoms",
      "publisher": "Family Practice (Oxford Academic), via PubMed",
      "source_type": "peer_reviewed",
      "statistic": "13/90 chilled subjects vs 5/90 controls self-reported cold symptoms in the 4–5 days after a 20-minute cold-foot immersion (P=0.047)",
      "excerpt": "\"There is a common folklore that chilling of the body surface causes the development of common cold symptoms, but previous clinical research has failed to demonstrate any effect of cold exposure on susceptibility to infection with common cold viruses. [...] 13/90 subjects who were chilled reported they were suffering from a cold in the 4/5 days after the procedure compared to 5/90 control subjects (P=0.047). [...] Acute chilling of the feet causes the onset of common cold symptoms in around 10% of subjects who are chilled. Further studies are needed to determine the relationship of symptom generation to any respiratory infection.\"\n",
      "source_date": "2005-12-01",
      "source_accessed": "2026-04-16",
      "archive_url": "http://web.archive.org/web/20260504061638/https://pubmed.ncbi.nlm.nih.gov/16286463/",
      "calculation_notes": "This is the canonical trial behind any \"cold feet causes colds\" claim. Critical qualifier the authors themselves flag: the study measured self-reported symptoms, not laboratory-confirmed new infections. The plausible mechanism the authors propose is that reflex vasoconstriction in the upper airway on cold- foot exposure reduces mucosal blood flow and temporarily lowers local defences — converting a pre-existing subclinical carriage of rhinovirus or another respiratory virus into a symptomatic cold. That is a modulation effect, not a causation effect. Without an underlying viral exposure, cooling the feet is not expected to produce illness from nothing. 90 subjects per arm gives an absolute difference of 8 percentage points (14% vs 6%); the confidence bound is wide, and no replication of comparable rigour exists at the scale needed to attach a per-winter probability to \"no slippers at home.\"\n",
      "independence_note": "Independent single-centre RCT at Cardiff (Common Cold Centre); editorially independent of the CDC and WHO sources. The Foxman 2015 mechanistic paper below provides a biological model compatible with Eccles' clinical result but was conducted in a separate lab with different methodology (mouse airway cells, not human subjects).\n"
    },
    {
      "url": "https://pubmed.ncbi.nlm.nih.gov/25561542/",
      "title": "Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells",
      "publisher": "Proceedings of the National Academy of Sciences (PNAS), via PubMed",
      "source_type": "primary_study",
      "statistic": "Rhinovirus replicates more robustly at 33–35 °C (nasal cavity) than at 37 °C (core body), with weaker interferon/antiviral response at the cooler temperature",
      "excerpt": "\"Most isolates of human rhinovirus, the common cold virus, replicate more robustly at the cool temperatures found in the nasal cavity (33–35 °C) than at core body temperature (37 °C). [...] These findings demonstrate that in mouse airway cells, rhinovirus replicates preferentially at nasal cavity temperature due, in part, to a less efficient antiviral defense response of infected cells at cool temperature.\"\n",
      "source_date": "2015-01-20",
      "source_accessed": "2026-04-16",
      "archive_url": "http://web.archive.org/web/20251208133031/https://pubmed.ncbi.nlm.nih.gov/25561542/",
      "calculation_notes": "Foxman et al. supplies the cleanest known mechanism for any cold-exposure- to-cold-illness signal: rhinovirus itself replicates better in a cooler nose, and the innate interferon response is weaker at 33 °C than at 37 °C. This makes Eccles' symptom-onset result biologically plausible without rescuing the folk model. The study is mouse airway cells in vitro, not an epidemiological measurement, and no study has translated the temperature- dependent replication curve into a per-exposure infection probability for a human wearing socks versus going barefoot. The mechanism is real; the epidemiological effect size at normal indoor conditions is not quantified.\n",
      "independence_note": "Yale laboratory study with no authorship, funding, or institutional overlap with the Cardiff Eccles group; treat as methodologically independent mechanistic corroboration. Independent of the CDC and WHO sources.\n"
    },
    {
      "url": "https://www.cdc.gov/common-cold/about/index.html",
      "title": "About the Common Cold",
      "publisher": "US Centers for Disease Control and Prevention",
      "source_type": "govt_report",
      "statistic": "More than 200 respiratory viruses cause colds; rhinoviruses are the most frequent cause; primary spread is droplets and contact",
      "excerpt": "\"More than 200 respiratory viruses can cause colds. Rhinoviruses are the most frequent cause of colds in the United States. [...] Most respiratory viruses are spread through droplets that an infected person releases when they cough or sneeze. These droplets can enter your body if you breathe them in or touch a contaminated surface and then touch your eyes, nose, or mouth.\"\n",
      "source_date": "2026-02-19",
      "source_accessed": "2026-04-16",
      "archive_url": "http://web.archive.org/web/20260402134530/https://www.cdc.gov/common-cold/about/index.html",
      "calculation_notes": "CDC's current patient-facing page is the plain-language anchor for the \"colds are viral, not thermal\" frame. The folk model treats cold exposure as causative; CDC treats virus exposure as causative and does not list chilling or being under-dressed indoors as a transmission route at all. The Eccles and Foxman results sit downstream of this: you still need the virus. Without rhinovirus or one of the other ~200 candidates in your airway, cold feet on tile do not produce a cold.\n",
      "independence_note": "Institutional CDC public-health guidance; editorially independent of the Eccles clinical trial and Foxman mechanistic paper, though it aligns with both.\n"
    },
    {
      "url": "https://www.ncbi.nlm.nih.gov/books/NBK535294/",
      "title": "Low indoor temperatures and insulation — WHO Housing and Health Guidelines",
      "publisher": "World Health Organization (via NCBI Bookshelf)",
      "source_type": "govt_report",
      "statistic": "WHO recommends minimum indoor temperature of 18 °C to protect general populations; higher minimum for vulnerable groups (older people, children, chronic cardiorespiratory illness)",
      "excerpt": "\"For countries with temperate or colder climates, 18 °C has been proposed as a safe and well-balanced indoor temperature to protect the health of general populations during cold seasons. [...] A higher minimum indoor temperature than 18 °C may be necessary for vulnerable groups including older people, children and those with chronic illnesses, particularly cardiorespiratory disease.\"\n",
      "source_date": "2018-11-27",
      "source_accessed": "2026-04-16",
      "archive_url": "http://web.archive.org/web/20260126080730/https://www.ncbi.nlm.nih.gov/books/NBK535294/",
      "calculation_notes": "WHO's guideline is the authoritative carve-out for the one scenario in which \"being under-dressed at home\" really does kill people: under-heated housing in cold climates, especially for the elderly and those with cardiorespiratory disease. The exposure here is the ambient indoor temperature (below ~18 °C sustained), not a barefoot afternoon in a heated 21 °C living room. The outcome is cardiovascular and respiratory morbidity and mortality, not the common cold. This is the reason the headline framing (\"folk belief overrated\") must be paired with an explicit vulnerable-group caveat rather than a blanket dismissal.\n",
      "independence_note": "WHO expert consensus guideline synthesising the cold-housing evidence base. Editorially independent of the Eccles, Foxman, and CDC sources and addresses a distinct exposure-outcome pair (sustained low ambient temperature → cardiovascular/respiratory death), not symptom onset of the common cold.\n"
    },
    {
      "url": "https://post.parliament.uk/research-briefings/post-pn-0752/",
      "title": "Winter mortality (POSTnote 752)",
      "publisher": "UK Parliamentary Office of Science and Technology",
      "source_type": "govt_report",
      "statistic": "Excess winter deaths in England and Wales ranged ~20,000–50,000/year 2000–2019; ~21.5% of excess winter deaths attributable to cold homes; most deaths from circulatory or respiratory disease among the elderly",
      "excerpt": "\"Between 2000 and 2019, excess winter deaths ranged from 20,000 to 50,000 a year [...] Most excess winter deaths are due to circulatory or respiratory diseases and the majority occur amongst the elderly population. [...] It has been estimated that 10% of excess winter deaths are attributable to fuel poverty and 21.5% to cold homes.\"\n",
      "source_date": "2024-01-01",
      "source_accessed": "2026-04-16",
      "archive_url": "http://web.archive.org/web/20260216223615/https://post.parliament.uk/research-briefings/post-pn-0752/",
      "calculation_notes": "This is the population-scale number for the one real cold-in-the-home harm: under-heated housing kills elderly people through cardiovascular and respiratory pathways, not through infection. It does not apply to the folk-belief scenario (healthy adult, barefoot in a warm house) and should not be aggregated with the Eccles symptom-onset figure. Used here only to bound the vulnerable-group subgroup in the regional breakdown and to keep the caveats honest about who the folk warning, repurposed, actually applies to.\n",
      "independence_note": "UK Parliament research briefing drawing on ONS winter-mortality data and NICE fuel-poverty reviews. Editorially independent of the WHO guideline (though it references the same underlying epidemiology) and independent of the Eccles, Foxman, and CDC sources.\n"
    }
  ],
  "comparison_anchors": [
    {
      "label": "Shared-cup sip, any serious infection (healthy adults)",
      "lifetime_us_adult": 0.000001
    },
    {
      "label": "Shared-towel serious infection (casual dry towel)",
      "lifetime_us_adult": 0.000001
    },
    {
      "label": "Food poisoning death (lifetime, US adult)",
      "lifetime_us_adult": 0.000537
    }
  ],
  "regional_breakdown": [
    {
      "region": "Healthy adult, bare feet on tile in a normally heated home (~20–22 °C)",
      "probability": 0.000001,
      "notes": "No cohort has measured a respiratory-infection rate attributable to this scenario. Without an underlying viral exposure, cold feet on tile do not produce a cold. Point estimate is a structural \"effectively zero\" placeholder, not a measured rate.\n"
    },
    {
      "region": "Adult already carrying rhinovirus, acutely chilled extremities",
      "probability": 0.14,
      "notes": "Matches the Eccles 2005 arm: ~14% self-reported cold symptoms within 4–5 days after a 20-minute cold-foot immersion vs ~6% in controls. This is a symptom-conversion rate in an already-exposed population under a severe chilling protocol, not an infection rate from going sockless at home.\n"
    },
    {
      "region": "Frail elderly or infant in an under-heated home (<16–18 °C sustained)",
      "probability": 0.05,
      "notes": "Very rough. Order of magnitude derived from WHO cold-housing guidance and UK excess-winter-mortality attribution (~21.5% of ~20,000–50,000 annual excess winter deaths → cold homes, concentrated in over-65s). The dominant pathways are cardiovascular and respiratory, not viral infection. Included as the subgroup the folk warning might actually apply to, even though it is almost never the one a grandmother has in mind when telling a child to put on slippers.\n"
    },
    {
      "region": "Adult with Raynaud's phenomenon or cold-induced angina",
      "probability": 0.5,
      "notes": "For someone with a cold-triggered vascular or cardiac condition, bare feet on cold tile reliably produces the trigger (Raynaud's episode, anginal chest pain) — but this is the underlying condition expressing itself, not a new illness. Included only to flag that \"cold feet cause real symptoms\" is true in this subgroup without rescuing the viral- infection folk model.\n"
    }
  ],
  "short_label": "Bare feet indoors",
  "myth_framing": "overrated",
  "outcome_severity": "minor_harm",
  "exposure_pattern": "recurring",
  "outcome_type": "inconvenience",
  "valence": "negative",
  "caveats": "Two pieces of evidence complicate a clean dismissal of the folk belief and deserve to sit in the open. First, Johnson and Eccles (2005) found a modest but statistically significant increase in self-reported cold symptoms after a 20-minute cold-foot immersion (14% vs 6%, P=0.047) — not a new-infection signal, but a symptom-conversion signal in people likely already carrying a virus. Second, Foxman et al. (2015) showed that rhinovirus replicates preferentially at the cooler temperatures of the nasal cavity and that the innate interferon response is weaker there, giving Eccles' clinical result a plausible mechanism. Together these support a narrow reframing: chilling can modulate symptom onset in an already-exposed airway, not cause illness from nothing. The folk model (cold exposure → colds, from scratch) is still wrong; the fully skeptical counter-model (cold exposure does nothing at all) is also slightly wrong. The right answer is \"small modulation effect conditional on viral carriage, not a primary cause.\"\nSeparately, the one real and well-documented harm from being under-dressed indoors is not captured by the per-event framing at all: elderly people, infants, and those with chronic cardiorespiratory disease in homes sustained below ~16–18 °C have measurable excess cardiovascular and respiratory mortality (WHO 2018; UK POST 2024). The exposure there is ambient room temperature, not sockless feet, and the outcome is heart attack, stroke, and pneumonia, not the common cold. The folk warning and the real harm do not overlap neatly: the folk warning is usually delivered to healthy people in warm homes, and the real harm falls on frail people in cold ones.\n",
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    "scored_at": "2026-05-25",
    "methodology_version": "1.2"
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  "reviewer": "likelier-phase-8-agent",
  "last_reviewed": "2026-04-16",
  "reviewed": true,
  "generated_at": "2026-04-16",
  "image": {
    "alt": "A single pair of neatly arranged slippers rendered as a flat vector shape in muted grey-blue and off-white tones, centered on a calm empty background."
  },
  "attribution": "Likelier — https://likelier.app",
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