smogfog or haze combined with smoke and chemical pollutantsDense smog in urban centres has been linked to increased hospital admissions for respiratory illness.NoteDense smog in urban centres has been linked to increased hospital admissions for respiratory illness.Elon.io is an online learning platformWe have an entire course teaching IELTS Vocabulary — Band 7+ grammar and vocabulary.Start learning IELTS Vocabulary — Band 7+ now