Many Nigerians believe that exposure to cold weather during the Harmattan season causes illnesses such as catarrh, cough and flu, but medical experts say cold air itself does not cause infections.
Studies show that colds and flu are caused by viruses, not by cold temperatures.
However, the dry and dusty Harmattan conditions common between November and February can increase the spread of respiratory infections across the country.
Health experts explain that viruses responsible for illnesses such as the common cold and influenza spread through respiratory droplets from coughing, sneezing, talking or close contact with infected persons.
These viruses circulate year-round but tend to spread more easily during colder and drier periods.
According to researchers, cold and dry air helps respiratory viruses survive longer in the environment. During Harmattan, low humidity allows droplets released into the air to evaporate quickly, creating smaller particles that remain airborne for longer and are easier to inhale.
Cold air can also weaken the body’s first line of defence.
Breathing in cold air lowers the temperature inside the nose and throat, reducing blood flow and slowing immune responses that normally stop viruses before they cause infection.
Doctors note that dry air dries out the lining of the nose and throat, reducing the effectiveness of mucus, which normally traps and clears viruses from the airways.
This makes it easier for infections to take hold. Behavioural factors also play a role. During Harmattan, people tend to stay indoors more, often in crowded or poorly ventilated spaces.
This increases close contact and makes it easier for viruses to spread from person to person.
Reduced exposure to sunlight during this period may also lower vitamin D levels, which play a role in supporting immune function. Low vitamin D has been linked to weaker immune responses.
People with asthma, allergies or other respiratory conditions are particularly vulnerable, as Harmattan dust and cold air can worsen symptoms and increase susceptibility to infections.
Experts emphasise that simply going outside without a sweater or feeling cold does not directly cause illness. Instead,
Harmattan conditions act as a risk amplifier by creating an environment that supports virus survival, transmission and reduced immune defence.
They advise Nigerians to focus on preventive measures such as regular handwashing, avoiding crowded spaces when possible, improving indoor ventilation, staying hydrated, and seeking medical care when symptoms persist.
Public health specialists say understanding the difference between cold exposure and viral infection can help dispel long-held myths and encourage better health practices during the Harmattan season.
