The relationship between air pollutant levels and aneurysmal subarachnoid hemorrhage

The relationship between air pollutants, including fine particles (particulate matter [PM] < 10 μm and < 2.5 μm), and aneurysmal subarachnoid hemorrhage (SAH) has been inadequately studied, and the results remain inconclusive. In this study, we attempted to investigate the relationship between air pollutant levels and aneurysmal SAH.

Ninety-two patients diagnosed with aneurysmal SAH were retrospectively included in the study. Medical records were reviewed, and levels of pollutants, including those of sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and PM with an aerodynamic diameter < 10 and 2.5 μm (PM10 and PM2.5), were collected from the open-source Air Korea website for a period of 4 days. Independent t-tests were conducted to identify the difference in the pollutant levels between the data obtained on the day of aneurysm rupture (D-0) and the other 3 days (D-7, D-2, and D-1).

A majority (40.2%) of the patients experienced aneurysm rupture during the fall season when the mean daily pollutant levels were 0.004 ± 0.001 (ppm, SO2), 0.517 ± 0.218 (ppm, CO), 0.02056 ± 0.012 (ppm, O3), 0.02628 ± 0.015 (ppm, NO2), 36.36957 ± 24.538 (μg/m3, PM10), and 19.75581 ± 13.494 (μg/m3, PM2.5), respectively. The level of NO2 was significantly higher on the day of aneurysm rupture (P = .035) than on the other days, while the levels of CO and O3 were nonsignificantly higher (P = .081, P = .055, respectively) on the day of aneurysm rupture than on the other days. There was no significant differences in the PM levels between the 4 days.

A relationship between PM levels and aneurysm rupture was not identified. Only the levels of classic air pollutant (CO, O3, and NO2) were higher on the aneurysm rupture day than on the other days.