Chattogram district's Civil Surgeon's Office has categorised nine upazilas as red zones for Covid-19 infection.
Those are: Anowara, Banshkhali, Boalkhali, Chandanaish, Hathhazari, Patia, Rangunia, Rauzan, and Sitakunda.
Three upazilas -- Fatikchhari, Lohagora and Satkania -- are categorised as yellow zones and two others -- Mirsarai and Sandwip -- as green zones.
A total number of 1,579 persons have tested positive for Covid-19 under the 14 upazilas in the district till today, Civil Surgeon Sheikh Fazle Rabbi said.
So far, 5,235 person tested positive for coronavirus in both Chattogram city and district.
The cut-off value for considering red zone is 10 or more infected persons for every 1,00,000 population, between 3 and 10 in case of yellow zone, and less than 3 for green zone.