Study Links Air Pollution to Increased Nighttime Coughing

The analysis revealed that higher daily air pollution levels correlate with increased coughing, even when local pollution readings fall below the World Health Organization’s daily exposure limit. Researchers collected cough data through a mobile app, using the phone's microphone to passively record cough sounds. This approach created a large dataset that accounted for other factors influencing cough rates, such as weather and influenza prevalence.

Findings showed that a 10 microgram per cubic meter increase in particulate matter (PM2.5) resulted in a 2.4% rise in coughing levels. For example, in Los Angeles, cough rates surged during the January 2025 wildfires, supporting the link between daytime pollution and nighttime cough frequency.

Air pollution is a major health risk, causing an estimated seven million premature deaths each year. PM2.5 particles are particularly harmful as they can enter the lungs and bloodstream, potentially leading to health issues like heart disease and respiratory conditions. Dr. Tong Xia, lead author of the study, noted that coughing can indicate lung irritation or inflammation and may signal future health concerns.

Sleep Cycle employs sound data to track sleep quality, using AI algorithms to analyze recordings of breathing, snoring, and coughing. This dataset enables a more robust public health assessment, as highlighted by Professor Cecilia Mascolo from Cambridge's Computer Science and Technology department.

The research suggests that even exposure to levels of air pollution deemed acceptable can have adverse effects on health. Researchers emphasize the importance of finding ways to reduce exposure, such as using masks or air filters. The study was supported by various funding bodies, including the European Research Council and the UK Engineering and Physical Sciences Research Council.