In this paper, environmental productivity change is analysed through the production theoretic approach to index numbers. Specifically, pollution-adjusted Malmquist and Hicks-Moorsteen productivity indices are considered. These productivity indices are defined as combination of multiplicative distance functions. Non convex pollution-generating technology is assumed to estimate the pollution-adjusted Malmquist and Hicks-Moorsteen productivity measures. Moreover, the main sources of the environmental productivity change are displayed. An empirical illustration is provided by considering a sample of 20 Ecuadorian oil companies over the period 2014-2018. The results are estimated through a non parametric analytic framework.