Tahara M, Fujino Y, Yamasaki K, et al. - Researchers used a nationwide registry in Japan, to assess the incidence of acute exacerbation (AE) of idiopathic pulmonary fibrosis (AE-IPF) in correlation with short-term exposure to fine particulate matter. They also intended to ascertain the exposure-risk time window during 3 months prior to the diagnosis of AE-IPF. A case–control analysis was carried out to examine the correlation between AE-IPF incidence and short-term exposure to eight air pollutants, including particulate matter < 2.5 µm (PM _2.5 ). Experts analyzed 152 cases with surgically diagnosed IPF. They found a significant link of AE-IPF with an elevated mean exposure level of nitric oxide (NO) and PM _2.5 30 days before AE diagnosis. According to findings, PM _2.5 conferred a risk for the occurrence of AE-IPF, and the risk-exposure time window associated with AE-IPF may lie within 1–2 months prior to the AE diagnosis. Novel observations concerning the exposure to NO and AE-IPF require further inquiry.