Air pollution and sleep: Air pollution may be robbing millions of middle-aged and older adults of a good night’s sleep, according to an international review led by Dr Junxin Li of the Johns Hopkins University School of Nursing.
The team analysed recent evidence from around the world and found consistent links between higher pollution levels and shorter or poorer-quality sleep.
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The review focused on people aged 45 and older and identified 25 high-quality studies published since 2015, covering roughly 1.2 million participants across six countries, including China, India, the United States and Germany. Despite differences in geography and methods, the pattern held: long-term exposure to outdoor pollutants, particularly fine particulate matter (PM2.5), nitrogen dioxide (NOâ‚‚) and even carbon dioxide (COâ‚‚) as a marker of traffic and combustion, was associated with reduced sleep duration and lower sleep quality.
Researchers looked at both short-term pollution spikes and years-long exposure, using a mix of wrist-worn sleep trackers and structured interviews to assess sleep. Nine studies were similar enough in design to be pooled into a meta-analysis, allowing the team to estimate potential benefits from cleaner air policies across different settings.
The review suggests that cutting average PM2.5 levels by about half, from concentrations typical of busy urban roads to the World Health Organization’s guideline range, could lower the odds of poor sleep among middle-aged and older adults by roughly 10%.
Although older adults spend more time indoors, robust research on indoor air quality and sleep was comparatively sparse. Only six high-quality studies examined the home environment, most from China. Those studies consistently found worse sleep, more insomnia and shorter sleep time, among households using solid fuels such as wood or coal for cooking and heating, compared with homes using cleaner fuels.
The authors argue current policy largely targets outdoor sources, they note, while the evidence now points to a need for cleaner indoor air standards and practical guidance for households.
