Background:​ Fragility hip fractures (HF) are a major cause of disability in the elderly. Air pollution has been linked with higher risk of osteoporosis. However, the association between acute exposure to air pollution and fractures is still unclear.

Methods:​ We conducted a case-crossover study on patients with fragility HF admitted to the Orthopedic Unit of the University of Verona Hospital. In case-crossover studies each patient serves as its own control. We retrieved data on the monitoring of PM10 concentrations from the Italian institute of environment protection and research (ISPRA). Patients were linked to exposure to PM10 using ZIP code centroids. We employed conditional logistic regression to estimate the effect of acute exposure (30-day lag) on fracture risk.

Results:​ Data on 1041 patients (n = 757, 72.7 % female) with hip fragility fracture were retrieved. The incremental risk (every 10 μg/m³ increase in PM10 concentration) was 7.7 % (95 % CI 2.2–15.8) p 0.045 (Beta 0.074 SE 0.037). Exposure to PM10 was higher in the 30 days preceding a HF compared to the control period (mean exposure 32.8 μg/m³ and 31.7 μg/m³, respectively p 0.027 and AUC exposure 952.4 μg/m³ and 920.2 μg/m³, respectively, p 0.024). Case-crossover sensitivity analyses yielded similar results.

Conclusions:​ Acute exposure to environmental air pollution PM10 was associated with higher risk of fragility HF in a cohort of 1041 patients. Further studies are needed to ascertain the exact role of air pollution on fracture risk.