FRIDAY, Feb. 1, 2019 (HealthDay News) – A new study suggests that forests are evolving in such a way that they could emit more gas that contributes to smog, acid rain and respiratory problems.

"This study has profound implications for the quality of the future air." Human activities, such as fire suppression, fertilizer use and climate change, are pushing forest populations to move tree stands do not emit these gases to those who do, "said the study leader. Jonathan Raff.

These gases, called reactive nitrogen oxides, are produced by soil-borne bacteria, which feed on natural fertilizers made from ammonium and nitrogen from industrial and agricultural sources. . They then enter the atmosphere.

According to the study, as forests evolve, higher levels of nitrogen oxides are to be expected. This could make it more difficult for some regions to meet national air quality standards, Raff said in a press release issued by a university. He is an associate professor of public and environmental affairs at Indiana University of Bloomington.

According to Ryan Mushinski, a postdoctoral researcher, these gases are easy to miss because they are hard to detect. "Many people just do not consider the soil to be a major producer of chemicals that are harmful to the air," he added.

Some trees promote the release of nitrogen oxides; others not, according to the study.

The maple, sassafras and tulip poplar are among the trees that promote the release of the chemicals that cause smog. According to the study, they hunt for other species, such as oak, beech and walnut, whose microbes absorb reactive nitrogen oxides rather than releasing them.

The researchers used data from a USDA Forest Service inventory to examine soil data from 78,000 forest plots across the country.

According to the study, Indiana, Illinois, Michigan, Kentucky and Ohio are the two regions with the highest nitrogen oxide emissions from forest soils. Higher emissions are also expected from forests along the Mississippi River and parts of the eastern United States.

The United States Environmental Protection Agency (EPA) regulates and monitors levels of nitrogen oxides.

Mushinski, however, said that the current rules would not reduce soil emission increases, because air quality standards do not regulate the use of fertilizers or deposits d & # 39; nitrogen.

In addition to stricter regulation, Mushinski suggests allowing more controlled burns. These fires are an effective way of eliminating the tree species that help create the soil that emits nitrogen, he said.

"It's hard because people like trees like maples and poplars a lot," Mushinski said. "But without greater awareness or policy changes, we will not see a reduction in the harmful gases that they encourage."

The report was recently published in the Proceedings of the National Academy of Sciences.