CHENNAI, July 29: A nation-wide campaign against popluation explosion with the re-introduction of the ‘red triangle’ will commence within three weeks, according to Union minister of State for health, Renuka Choudhary. Six northern and north-eastern states have been selected for this intensive programme. She extolled Tamil Nadu’s efforts in campaigning against spread of AIDS and informed that awareness programmes such as the ones initiated by the TN government will be taken up in other States as well.