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Table 4 Classification of geo-accumulation index

From: Effect of urbanization on heavy metal contamination: a study on major townships of Kannur District in Kerala, India

Geo-accumulation index Igeo class Pollution intensity
 > 5 6 Very strongly polluted
 > 4–5 5 Strong to very strongly polluted
 > 3–4 4 Strongly polluted
 > 2–3 3 Moderately to strongly polluted
 > 1–2 2 Moderately polluted
 > 0–1 1 Unpolluted to moderate polluted
 < 0 0 Practically unpolluted
  1. Asa et al. (2013) and Vineethkumar et al. (2020)