Hot spots in the sky

An international team of public health experts blames Canadian wildfires for “global dimming” that contributed to poor air quality in the United States two years ago. After smoke from Canada’s 2023 wildfire season wafted southward, hazy, orange skies enveloped states ranging from Montana to Georgia to New York. Recent studies aim to quantify the smoke’s harm to human health.

The team of researchers published a paper April 21 in Communications Earth & Environment that analyzed smoke particulate matter from June 7, 2023, the worst day of wildfire smog in New York and New Jersey. The smoke’s brown carbon particles blocked sunlight, lowering the temperature by around 5 degrees Fahrenheit, limiting air circulation, and trapping air pollutants close to ground level. The study noted research showing a surge in asthma-related emergency room visits on June 7 (up 44% in New York City and 82% statewide) and suggested exposure to these air pollutants had both short- and long-term adverse respiratory effects.

Meanwhile, a December 2024 study in JAMA Network Open connected the wildfire smoke to heart-lung disease. University of Maryland researchers identified six “hot spot” days in June 2023 when the levels of wildfire-related air pollution in Maryland exceeded the U.S. Environmental Protection Agency’s standards for safe air quality. On these hot spot days, Maryland residents were 18% more likely to seek medical care for cardiopulmonary complications.

The United States has its own wildfire problems, of course. An analysis published April 4 in JAMA Network Open found that exposure to fine particulate air pollution from smoke during California’s 2020 wildfire season worsened local residents’ mental health. Harvard and Stanford University researchers reported a higher number of mental-health-related ER visits in California between July and December 2020. For every 10-microgram uptick in fine particulates per cubic meter of air, depression rates rose by 15% and other mood-related disorders by 29%.

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Heartbreak breakthrough

Scientists have figured out how to mend a broken heart—at least in rats. In a new study, injection of a protein-like polymer after a heart attack prevented heart failure for up to five weeks in rodents. Heart attacks cause stress and inflammation to heart muscles, often leading to heart failure. No effective treatment for heart failure exists, and more than half of Americans with it die within five years.

According to the study, published April 25 in Advanced Materials, the new polymer therapy works by mimicking Nrf2, a protein that prevents inflammation-induced cell deterioration. Without the polymer therapy, the protein Keap1 normally binds to Nrf2 and thwarts the latter’s ability to stop cell degradation. But the protein-like polymer binds Keap1, allowing Nrf2 proteins to continue their anti-inflammatory work.

Lead study author Nathan Gianneschi said the new therapy, after further clinical testing, could potentially treat a wide range of diseases, including multiple sclerosis and kidney disease. —H.F.