The persistent presence of nitrates in the atmosphere has long been a concern for environmental scientists. Despite efforts to reduce emissions over the past few decades, nitrate levels remain stubbornly high. A recent study published in Nature Communications sheds light on this enigma, revealing that chemical processes within the atmosphere are responsible for the persistence of these pollutants.

The research team led by Hokkaido University’s Professor Yoshinori Iizuka examined nitrate deposition history from 1800 to 2020 in an ice core taken from southeastern Greenland. The results showed a gradual increase in nitrates up to the 1970s, followed by a slower decline after the 1990s. This trend mirrors the changes in emissions of nitrate precursors over the same period.

The study’s findings suggest that factors other than emission reductions are driving the persistence of atmospheric nitrates. The researchers used a global chemical transport model to investigate these factors and discovered that atmospheric acidity is the key culprit. As acidity levels rise, more nitrates become trapped in particulate form, enabling them to persist longer and travel farther.

The implications of this study are significant. Accurate measurements of particulate nitrates in ice cores provide valuable data for refining climate modeling predictions. Moreover, the findings suggest that atmospheric nitrates will soon replace sulfates as the primary aerosol in the Arctic, further amplifying warming in the region.

As Professor Iizuka notes, “Ours is the first study to present accurate information for records of particulate nitrates in ice cores.” The persistence of these pollutants highlights the importance of continued research into atmospheric chemistry and climate modeling. By understanding the complex interactions within our atmosphere, we can better predict and prepare for the challenges that lie ahead.

The air we breathe has long been a concern for public health, but a recent study by Emory University researchers sheds light on a specific and alarming link between air pollution and pregnancy risks. Published in Environmental Science & Technology, the research reveals that exposure to tiny particles in air pollution during pregnancy can disrupt maternal metabolism, leading to increased risk of various negative birth outcomes.

The study analyzed blood samples from 330 pregnant women in the Atlanta metropolitan area, providing a detailed insight into how ambient fine particulate matter (PM2.5) affects the metabolism of pregnant women and contributes to increased risks of preterm and early term births. This pioneering work marks the first time researchers have been able to investigate the specific fine particles responsible for these adverse outcomes.

“The link between air pollution and premature birth has been well established, but for the first time we were able to look at the detailed pathway and specific fine particles to identify how they are reflected in the increased risk of adverse birth outcomes,” says Donghai Liang, PhD, study lead author and associate professor of environmental health. “This is important because if we can figure out the ‘why’ and ‘how,’ then we can know better how to address it.”

Previous research has shown that pregnant women and fetuses are more vulnerable than other populations to exposure to PM2.5, which is emitted from combustion sources such as vehicle exhaust, industrial processes, and wildfires. This increased vulnerability is linked to a higher likelihood of preterm births, the leading cause of death globally among children under the age of five.

Preterm birth is associated with complications such as cerebral palsy, respiratory distress syndrome, and long-term noncommunicable disease risks. Early term births (37-39 weeks of gestation) are also linked to increased neonatal morbidity and developmental challenges. Approximately 10% of preterm births worldwide are attributable to PM2.5 exposure.

As an air pollution scientist, Liang emphasizes the importance of addressing this issue beyond simply asking people to move away from highly polluted areas. “From a clinical intervention standpoint, it’s critical to gain a better understanding on these pathways and molecules affected by pollution,” he says. “In the future, we may be able to target some of these molecules to develop effective strategies or clinical interventions that could help reduce these adverse health effects.”

This groundbreaking study highlights the urgent need for policymakers and healthcare providers to take action against air pollution, particularly in areas with high levels of PM2.5 exposure. By understanding the molecular link between air pollution and pregnancy risks, we can work towards developing targeted solutions to mitigate these negative outcomes and protect the health of future generations.

California’s Salton Sea has been emitting high levels of hydrogen sulfide, a toxic gas that can cause headaches, nausea, fatigue, and long-term neurological and respiratory effects. A recent study found that this pollution is vastly underestimated by government air-quality monitoring systems, putting communities around the lake at risk.

The Salton Sea, located about 160 miles east of Los Angeles, has been maintained mostly by runoff from the surrounding basin since 1907. However, due to a hotter and drier climate, and policies that diverted more water away from the valley, the lake’s levels began dropping rapidly in the second half of the 20th century.

This desiccating organic matter emits hydrogen sulfide, which has been shown to cause health problems at even low levels of exposure. The researchers found that between 2013 and 2024, air quality sensors in communities surrounding the Salton Sea frequently showed hydrogen sulfide readings exceeding State of California standards.

The exceedances were most likely in the summer and most pronounced at the Torres Martinez site, which is the closest to the lake. In the month of August for each year from 2013 to 2024, Torres Martinez had an average of more than 250 hours of readings in excess of state standards.

A comparison of wind direction data confirmed that exceedances tended to happen when the wind was blowing into communities from the direction of the lake. An additional sensor placed in the shallow waters of the lake picked up consistently high hydrogen sulfide levels regardless of wind direction, helping to confirm that the lake is indeed the source of hydrogen-sulfide emissions.

The findings highlight the need for increased air-quality monitoring around the Salton Sea, as well as further study of the public health consequences of these emissions. The researchers say that community residents exposed to hydrogen sulfide are impacted not only in their physical health but also in their quality of life.

“This is a textbook case of environmental injustice,” said Aydee Palomino, project manager for the Campaign for Thriving Salton Sea Communities at Alianza Coachella Valley and a study co-author. “People in the Coachella and Imperial valleys are breathing in pollutants that are under the radar of traditional monitoring systems.”

The research was supported by Burroughs Wellcome Fund, the Google Environmental Justice Data Fund, and NASA. However, the unexpected termination of the NASA grant has disrupted planned follow-up work, including efforts to share and discuss the findings with members of the affected community.