Table 5 Nemerow Pollution Index soil classes (adapted from Kowalska et al.44).

From: Are heavy metals in urban garden soils linked to vulnerable populations? A case study from Guelph, Canada

Class

NPI value

Quality of soil

I

< 0.7

Clean

II

0.7–1

Warning limit

III

1–2

Slight pollution

IV

2–3

Moderate pollution

V

> 3

Heavy pollution

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