Increased global temperatures may lead to high levels of fungus in the air.
The average surface temperature of Earth has risen about 2.0 degrees Fahrenheit since the late 19th century, driven by increased carbon dioxide (CO2) and other emissions, according to NASA. A majority of the world’s warming temperatures occurred within the past 35 years, with nearly all of the 17 warmest years occurring since 2001.
Due to the increasing concern of global warming, many countries have implemented regulations about limiting harmful emissions and other standards to prevent further adverse effects on the environment and human health.
A new study published by the American Journal of Physiology — Cell Physiology recently found that exposure to outdoor fungus can cause increased oxidative stress in airways. This can lead to weakening of the airway’s defense against infection- and allergy-causing pathogens.
Alternaria alternatais is a fungus that actively produces spores when the weather is warm and dry during the summer and fall. Previous research shows that the fungus creates up to 3 times more spores when CO2 levels are high, as is the case with a warmer climate. Exposure to this fungus can lead to allergy and asthma symptoms.
In the new study, the authors analyzed the epithelium of human airways and introduced Alternaria to examine the effects of fungal exposure on the permeability of the epithelium.
When permeability is compromised, compounds can leak into the airways. Compromised barrier function can also introduce bacteria and allergens into the airways, according to the study. These factors leave the airways at an increased risk of inflammation and infection.
The authors also examined oxidative stress in cells exposed to the fungus. When exposed to Alternaria, the cells were observed to be more damaged compared with non-exposed cells.
Specifically, cells exposed to the fungus were found to have higher concentrations of calcium, which resulted in the cells secreting more salt and fluid than normal, according to the study. While salt and fluid secretion is necessary to keep the lungs clear of allergens, long-term exposure to the fungus may not be beneficial.
"However, prolonged exposure [to Alternaria] leads to disruption of epithelial barrier function that would ultimately reduce mucociliary clearance," the researchers wrote.
A reduction in mucociliary clearance typically leads to worsened asthma and allergy symptoms, according to the study.
The authors wrote that current climate trends may be escalating asthma and allergy symptoms among the population due to increased CO2 levels.
"These results suggest that continuing increases in atmospheric CO2 associated with global climate change will increase both the level of Alternaria exposure and antigenicity [the ability to produce an immune response] of spores that come in contact with the airways,” the authors concluded.