Ambient air pollution is responsible for over 4 million premature deaths worldwide each year, with well-documented effects on respiratory and cardiovascular health. But its impact runs deeper — all the way to women’s reproductive systems, as shown by the data analysis of over 2 million menstrual cycles.

A groundbreaking new study, Dust Bloom, reveals a previously underexplored connection: long-term exposure to fine particulate matter (PM2.5) is associated with irregular menstrual cycles — a key indicator of women’s overall health.

Published in The Lancet Planetary Health, the study is a collaboration between the MIT Senseable City Lab, the University of Colorado Denver, and Clue, a menstrual health app used by millions globally. Researchers analyzed over 2.2 million menstrual cycles from 92,550 users across 230 cities in the United States, Mexico, and Brazil, spanning 2016 to 2020. This is one of the most comprehensive datasets ever used to investigate environmental effects on menstrual health.

“Menstrual cycles are a vital sign of health, yet they’ve been largely ignored in environmental health research,” says Priyanka deSouza, co-author and professor at the University of Colorado Denver. “This study sheds light on a critical, yet often overlooked, consequence of air pollution — particularly for women.”

“The integration of large-scale high-res health data and advanced environmental monitoring — including satellite-derived air quality measures — is transforming how we study public health,” says Carlo Ratti. “It’s especially crucial in regions like Latin America, where communities face disproportionate environmental harm.”

Dust Bloom not only highlights the hidden costs of pollution on women’s health but also demonstrates the power of digital health data in uncovering insights that might otherwise remain invisible. When science centers sex-specific outcomes, it opens new pathways to protect and promote the well-being of all.