Does Abrupt Weather Temperature Change Increase Risk of Upper Respiratory Infection?
Yes, abrupt drops in ambient temperature significantly increase the risk of upper respiratory tract infections through multiple physiological mechanisms, including impaired nasal mucosal defenses, reduced interferon responses, and conversion of subclinical viral infections into symptomatic disease.
Primary Mechanisms of Temperature-Related Susceptibility
Cold Air Exposure and Nasal Defense Impairment
Inhalation of cold, dry air directly damages the protective nasal epithelium by creating a hyperosmolar environment that disrupts tight junctions between epithelial cells, activates mast cells, and triggers inflammatory mediator release 1.
Cold air exposure causes immediate inflammatory responses followed by late-phase reactions lasting up to 10 hours, characterized by elevated histamine levels and increased vascular permeability 1.
Cooling of the nasal epithelium inhibits critical respiratory defenses, including mucociliary clearance and phagocytic activity of leukocytes, which are essential for clearing pathogens 2.
The nasal mucosa's temperature drops significantly with cold air inhalation—at flow rates of 20 L/min with cold dry air, nasopharyngeal temperatures can fall to 25.9°C compared to normal body temperature 3.
Impaired Antiviral Immune Responses
Low temperatures directly suppress interferon-induced antiviral defenses—cells maintained at 25°C and 33°C expressed significantly lower levels of myxovirus resistance protein 1 (MxA) and 2'5'-oligoadenylate synthetase 1 (OAS1) compared to cells at 37°C after influenza virus infection 4.
Exogenous β-interferon treatment effectively reduced viral replication at 37°C but failed to do so at 25°C, demonstrating temperature-dependent immune dysfunction 4.
Exposure to cold suppresses broader immune responses beyond interferon pathways, including vasoconstriction in respiratory tract mucosa that further compromises local immunity 5.
Evidence for Temperature Change as a Risk Factor
Acute Temperature Drops
A 2023 epidemiological study using susceptible-infected-recovered-susceptible modeling found that the mean difference (drop) in temperature over the prior week was strongly negatively associated with new influenza cases (coefficient: -0.835,95% Bayesian credible interval -0.840 to -0.830) 6.
The interaction between mean temperature and temperature change was also negatively associated with infection risk (-0.192), indicating that steep temperature drops in relatively warm environments pose the highest infection risk 6.
This contradicts the simple "cold weather" hypothesis and supports the specific role of abrupt temperature change rather than absolute cold 6.
Body Surface Cooling Mechanism
Acute cooling of the body surface (such as from wet clothes or hair) causes reflex vasoconstriction in the nasal passages and upper airways, which may convert asymptomatic subclinical viral infections into symptomatic clinical infections 7.
This mechanism explains the common observation that "chills" precede cold symptoms, even though viral inoculation studies without cold exposure have failed to demonstrate increased susceptibility 7.
The duration of cold exposure correlates with infection risk—longer exposure periods increase both the likelihood of developing respiratory tract infections and mortality from them 5.
Environmental and Indoor Air Quality Factors
Ventilation and Indoor Environment
Poor indoor air quality from insufficient ventilation is the strongest housing-related risk factor for respiratory illness, with indoor pollutant concentrations typically 2-5 times higher than outdoor levels 1.
The WHO identifies adequate natural ventilation as one of the most effective measures to reduce infection spread in both healthcare and residential settings 1.
Cold housing conditions are linked to higher rates of respiratory and cardiovascular adverse effects through multiple pathways including reduced immune function 1.
Optimal Humidity Range
Maintaining indoor relative humidity between 40-60% optimizes mucociliary clearance, preserves airway immune defenses, and reduces virus-laden aerosol generation 1.
Cold air holds less moisture, so heating cold outdoor air without humidification creates excessively dry indoor environments that compromise respiratory defenses 1.
Clinical Implications and Prevention
High-Risk Scenarios
Sudden weather changes from warm to cold temperatures represent the highest-risk period, particularly when the temperature drop is steep 6.
Exposure to cold, dry air during exercise or heavy breathing (flow rates >20 L/min) causes more severe nasal cooling and greater epithelial disruption 3.
Children are particularly vulnerable due to higher minute ventilation rates and more time spent outdoors 3.
Protective Measures
Maintain adequate indoor heating to prevent body surface cooling and nasal vasoconstriction—temperatures below 18°C indoors are associated with negative health effects including increased blood pressure and cardiovascular stress 3.
Ensure proper humidification when heating indoor air, targeting 40-60% relative humidity to preserve mucosal defenses 1.
Increase ventilation with fresh outdoor air to dilute indoor pollutants while maintaining thermal comfort 1.
During periods of abrupt temperature drops, minimize prolonged exposure to cold outdoor air and avoid getting wet, which amplifies body surface cooling 5, 7.
Common Pitfalls
Do not dismiss patient reports of "catching a cold" after temperature exposure—the physiological mechanisms are well-established even though early viral inoculation studies failed to demonstrate this effect 7.
Recognize that the temperature change itself, not just absolute cold, drives infection risk—warm environments with sudden cooling may pose greater risk than consistently cold environments 6.
Avoid over-reliance on recirculated indoor air without adequate fresh air exchange, as this increases pathogen concentration regardless of temperature 1.