On six days of the week, low-flying aircraft follow their course only metres above our heads, leaving behind a trail of citizens plagued by the constant incredibly loud noise.

plagued 是动词 plague 的过去分词形式，在句中表示被动。plague 本意是"瘟疫、灾祸"，作为动词时引申为"使痛苦、折磨"的意思，常用来描述持续不断的困扰或烦恼。在这里 plagued by noise 表示"被噪音持续困扰/折磨"。