The national capital stands third on the list of states and Union territories with most contaminated sites, according to the Central Pollution Control Board data.
There are 112 sites in India contaminated by toxic and hazardous substances. Besides, there are 168 sites that may be contaminated but require investigation and confirmation, as per the CPCB.
Odisha tops the list with 23 contaminated sites, followed by Uttar Pradesh (21) and Delhi (11).
Bhalswa and Ghazipur landfill sites, industrial areas at Jhilmil, Wazirpur, New Friends Colony, Dilshad Garden and Lawrence Road are among the 11 contaminated sites in Delhi.
Also, there are 12 "probably contaminated sites" in the national capital.
According to the Union Environment Ministry, 'Contaminated Sites' are delineated areas in which the "constituents and characteristics of the toxic and hazardous substances, caused by humans, exist at levels and in conditions which pose existing or imminent threats to human health and the environment".
Contaminated sites may include production areas, landfills, dumps, waste storage and treatment sites, mine tailings sites, spill sites, chemical waste handler and storage sites located in various land uses.
'Probably Contaminated Sites' are areas with alleged but not scientifically proven presence of such contaminants or substances.
Remediation work has been started to clean up 14 contaminated sites in 7 states on the directions of the National Green Tribunal.
These states include Gujarat, Jharkhand, Kerala, Maharashtra, Odisha, Tamil Nadu and Uttar Pradesh.
Remediation of contaminated sites involves cleaning of contaminated media — soil, groundwater, surface water and sediments — by adopting various in-situ or ex-situ clean-up technologies up to a predefined remediation target levels for each identified constituent.