Researchers have found evidence that living in areas prone to wildfire smoke may negatively impact an individual's life expectancy.

In many parts of the contiguous United States, wildfires are rapidly growing more intense, endangering the humans and wildlife that live in the region. Even once fires are doused, serious health risks remain because of the many adverse effects caused by wildfire smoke and the airborne pollution that the blaze releases into the atmosphere.

Now, scientists at The Ohio State University have found that not only is wildfire smoke linked to a shortened lifespan, it also greatly diminishes the positive health impacts of local greenspaces, like forests or parks.

"When considering the environment's effect on human life expectancy, we have to account for all kinds of factors," said Yanni Cao, lead author of the study and a postdoctoral researcher in environmental health services at Ohio State. "Forests, for example, provide essential ecosystem services to mitigate the impact of wildfire smoke because they can purify the air."

Generally, greenspaces benefit human health by helping to regulate the local ecosystem and climate through capturing carbon dioxide, oxygen production and air filtration as well as by providing open spaces to foster social and community connection. It's why higher levels of greenspaces are usually correlated with higher life expectancies.

But because these lush areas can essentially act as fuel for wildfires, their presence is also tightly correlated with higher wildfire smoke emissions, said Cao. Due to its high toxicity, human exposure to this smoke has been known to cause respiratory issues, cardiovascular disease, and an increase in the risk of dementia and hospitalisation.

The research was presented this week at the annual meeting of the American Geophysical Union.

To better understand the complex role these factors play in determining the average number of years an individual might live, researchers analysed more than 66,000 pieces of U.S. census data collected between 2010 and 2015.

Their findings concluded that for every additional day of smoke exposure, a person's life expectancy could be expected to decrease by about 0.02 years -- or about one week.

Conversely, living in a green neighborhood can be beneficial, as even a 1% increase in these spaces can lead to a slight life expectancy increase. While wildfire smoke can negate the benefits of greenspace, the team's results suggest that sociodemographic factors such as income, population density, age and race also significantly impact future life expectancies.

"Families with higher average household income have better living conditions, more comprehensive nutritional intake, and tend to have better sanitary conditions and living habits," said Cao. Widespread inequality for minorities means they are less likely to have those protective factors.

People living in areas with extensive greenspaces should carefully consider appropriate health protection measures if they are exposed to wildfire smoke, said Jianyong Wu, co-author of the study and an assistant professor in environmental health sciences at Ohio State.

"Our findings contribute to a deeper understanding of how environmental factors influence public health," he said. "We want our research to offer valuable guidance for future urban planning and public health policies that are aimed at improving life expectancy across the country."

Although this study focuses on the U.S. as a whole, researchers note that future work will aim to discover if wildfires have a similar effect on adult and child mortality in regions like Ohio, where the populace often deals with other kinds of environmental extremes, like drought.

"The goal of this work is to raise awareness about the health impacts of wildfire," said Cao. "To do that, we need to enhance risk communication with the public and further strengthen research on the effects of these disasters."