New Delhi, Oct. 28 -- The Central Pollution Control Board (CPCB) has informed the National Green Tribunal (NGT) that it has detected the presence of heavy metals in Delhi's air, with concentrations of copper, zinc, chromium, and molybdenum ranging between 0.1% and 2% of the total particulate matter (PM10) concentration in the region. In a report submitted to the tribunal, the CPCB said samples were collected from Delhi and nine other cities during June and July this year. In Delhi, samples were taken from Pitampura, Siri Fort, Janakpuri, and Shahdara, according to the report uploaded on October 26. The NGT had taken suo motu cognisance of a news report published in September last year, which cited a study highlighting the presence and rising trend of heavy metals in east Delhi's air. The tribunal had directed the CPCB to analyse the data and submit its findings. In its report, the CPCB said ambient air quality monitoring for particulate matter (PM10) and metals - including zinc, chromium, copper, and molybdenum - was conducted across 10 metropolitan cities: Jaipur, Bhopal, Lucknow, Ahmedabad, Nagpur, Kolkata, Bengaluru, Visakhapatnam, and Chennai....