A common belief is that rain or cold weather directly causes illnesses like the common cold. Many associate getting wet with immediate sniffles and sneezes. However, the link between environmental conditions and illness is more complex than a simple cause-and-effect.
The Real Causes of Colds and Flu
Illnesses like the common cold and influenza are caused by specific viruses, not environmental factors like rain or cold. The common cold is triggered by many respiratory viruses, with rhinoviruses being common culprits. These microscopic viruses must enter the body to cause infection.
Transmission occurs through airborne droplets from an infected person’s coughs, sneezes, or talks. Viruses also spread through direct physical contact, like shaking hands, or indirectly by touching contaminated surfaces and then one’s eyes, nose, or mouth. Infection requires encountering the virus.
How Cold and Wet Might Influence Health
While rain does not directly cause colds or flu, being cold and wet might indirectly affect the body’s response to existing viruses or facilitate their spread. When exposed to cold, the body conserves heat through physiological responses. One response is peripheral vasoconstriction, where blood vessels near the skin’s surface narrow, reducing blood flow to extremities.
Reduced blood flow, particularly in nasal passages, could affect the local immune response, as fewer immune cells might be present to fight inhaled viruses. Prolonged cold exposure can also induce a stress response, releasing hormones like cortisol that temporarily suppress immune function. Cold weather often leads to people spending more time indoors, increasing viral transmission.
Beyond the Sniffles: Other Health Concerns
Beyond common respiratory infections, prolonged or severe exposure to rain and cold poses risks like hypothermia. Hypothermia occurs when the body loses heat faster than it produces it, causing core temperature to drop below 95°F (35°C). Symptoms include shivering, confusion, slurred speech, clumsiness, and pale or bluish skin. Untreated hypothermia can lead to serious complications, including heart and respiratory failure, and can be fatal.
A concern, especially during heavy rainfall or flooding, is exposure to contaminated water. Floodwater can contain a hazardous mix of human and animal waste, sewage, chemicals, and other debris. Contact with such water can lead to skin rashes, wound infections, and gastrointestinal illnesses if ingested. While rain itself is not inherently harmful, the conditions it creates or the contaminants it carries can present genuine health hazards.