When seasons change, temperature changes as well. Changing temperatures provides ideal conditions for the pathogens, environmental bacteria, and infection-inducing fungi to thrive. The hypothesis that common cold viruses replicate better in colder environments was proven by a study conducted by Yale University’s professor of immunobiology Akiko Iwasaki in 2015. In the study, Iwasaki and a group of Yale researchers compared the immune response of mice to rhinovirus (a type of common cold virus) when the mouse cells were exposed to core body temperature (37 degrees celsius) or 33 degrees celsius. The results showed that the mice’s immune response to rhinovirus was impaired when exposed to lower temperatures than normal body temperature. Thus, seasonal viruses such as Influenza thrive in the fall and winter.

Apart from viral or bacterial infections, irritants and allergies can also trigger coughs. The pollen from a variety of weeds and grasses can stimulate allergic reactions. One plant that is often responsible for allergies is ragweed, a tall, willowy plant. Kenneth Mendez, president and chief executive of the Asthma and Allergy Foundation of America, states that climate change is causing the allergy season to become more intense. Higher carbon dioxide emissions induce the amount of pollen produced by ragweed, increasing irritants in the air and making allergies feel a lot worse.

Another cause of allergies in the fall is mold. When foliage begins to decay, the damp surrounding creates an ideal environment for the growth of mold. When mold is inhaled, it can trigger allergic reactions such as coughs, stuffy nose or chest tightness, but can also cause a more severe allergy called Allergic bronchopulmonary aspergillosis (ABPA). ABPA is an allergy to a fungus in soil called Aspergillus fumigatus which causes allergic and inflammatory reactions. The immune systems of people previously diagnosed with asthma or cystic fibrosis overreact to the antigens of Aspergillus fumigatus. This can result in permanent lung damage.

Asthma is a condition that inflames or narrows the airways in the lungs. Fall is a hard time for asthma sufferers, because allergens in the air such as mold or pollen can worsen some of the symptoms, including wheezing, coughs, shortness of breath and chest tightness . Moreover, the irritation of the cold dry air tightens the muscles around airways and causes inflammation in the lungs. It is important to be aware of asthma triggers and avoid them whenever possible.

Fall is a season of comfort, pretty leaves and sweater weather. While having fun, it is important to pay attention to our body and take care of ourselves.