Background <p>Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by thunderclap headaches and transient cerebral vasoconstriction. The influence of environmental factors, particularly air pollution and weather conditions, on RCVS remains poorly understood.</p> Methods <p>From 2010 to 2022, clinical data from two hospitals were analyzed alongside air pollution and meteorological data provided by Air Pays de la Loire and Météo-France. A time-stratified case-crossover design was used to evaluate the association between RCVS onset and daily mean concentrations of O₃, PM₁₀, PM_2.5, and NO₂, using spatial modeling of residential exposure. Pollutant effects were examined over lag periods of up to three days, with adjustments for temperature and atmospheric pressure.</p> Results <p>A total of 216 patients were included (mean age: 39.9&#xa0;years; SD: 12.3; sex ratio: 1:1). In the three days preceding RCVS onset, only PM₁₀ concentrations remained significantly higher compared to the day of onset (19.03 vs. 17.99&#xa0;µg/m³, <i>P</i> = 0.0029). A significant downward trend in PM₁₀ levels was observed over this period (slope −0.735, <i>P</i> = 0.0286), whereas no significant changes were found for PM_2.5, O₃, or NO₂. PM₁₀ was the only pollutant significantly associated with RCVS onset across lag days (Lag 0: OR 0.747, 95% CI: 0.579–0.962, <i>P</i> = 0.024; Lag 1: OR 0.770, 95% CI: 0.599–0.989, <i>P</i> = 0.041; Lag 2: OR 0.776, 95% CI: 0.604–0.997, <i>P</i> = 0.047; Lag 3: OR 0.768, 95% CI: 0.599–0.984, <i>P</i> = 0.037). After adjusting for atmospheric pressure and temperature, these associations were no longer statistically significant.</p> Conclusion <p>This study suggests a short-term decrease in PM₁₀ levels prior to RCVS onset and a negative association between PM₁₀ concentration and occurrence. These findings contribute to understanding the potential environmental triggers of RCVS in the context of changing air quality and climate.</p>