Huaying Liu

Fine particulate matter (PM2.5) is a leading environmental cause of millions of deaths annually from cardiovascular, metabolic, and respiratory diseases. (1) Reducing PM2.5 mass has long been adopted worldwide as a strategy to combat air pollution. The World Health Organization further decreased the PM2.5 annual mean guideline limit to 5 μg/m3. Recently, China also readjusted its yearly guideline level from 35 to 25 μg/m3. However, a troubling phenomenon has emerged.

Introduction The incidence of inflammatory bowel disease (IBD) has risen steadily not only in Western countries but also in Asia (1). IBD encompasses Crohn’s disease (CD) and ulcerative colitis (UC), both of which are chronic inflammatory disorders of the gastrointestinal tract. Recent studies have implicated genetic factors, environmental triggers, dietary influences, and alterations in the gut microbiota as key contributors to IBD flares (2).