Objective:

To determine the correlation between particulate matter (PM) 2.5 and PM10 levels and clinical exacerbations of neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS).

Background:

PM2.5 and PM10 have been linked to various neurological disorders; however, their effects on central demyelinating diseases such as NMOSD and MS are not well established. This study aimed to investigate the relationship between ambient PM2.5 and PM10 levels and disease exacerbations in patients with MS and NMOSD.

Design/Methods:

Patients with MS or NMOSD exacerbations (2013–2022) from the Northern Thailand Registry were categorized by air pollution exposure (PM2.5 >15 μg/m³, PM10 >45 μg/m³). Outcomes included clinical features, Expanded Disability Status Scale (EDSS) scores, and functional status.

Results:

A total of 126 exacerbations were analyzed in the PM2.5 dataset (mean age 44.9 ± 14.9 years; 114 NMOSD cases; 49 first exacerbations) and 135 exacerbations in the PM10 dataset (mean age 44.9 ± 14.9 years; 121 NMOSD cases; 54 first exacerbations), with the peak incidence occurring four months after the highest air pollution levels. Patients exposed to PM2.5 demonstrated greater disease severity, with significantly higher proportions of unfavorable EDSS outcomes at both the time of exacerbation and at 90 days (56.3% vs. 23.6%, P < 0.001 and 47.9% vs. 16.4%, P < 0.001, respectively). Gadolinium-enhancing lesions were more frequent in the PM2.5 exposure group (56.3% vs. 36.4%, P = 0.03). Moreover, the use of second-line treatment with plasma exchange was higher among PM2.5-exposed patients (21.1% vs. 7.3%, P = 0.03). Overall, PM2.5 exposure—but not PM10—was associated with unfavorable EDSS outcomes, radiological activity, increased need for plasma exchange, and longer hospitalization.

Conclusions: