Sectors contribute differently to the total level of CO2 emissions per capita, since they are heterogeneous in terms of GDP structure. This work investigates the Environmental Kuznets Curve hypothesis considering a set of twelve of the fourteen OPEC countries. It contributes to previous literature exploring the Environmental Kuznets Curve relationship by analysing how economic activity sector diversification impacts the relationship between economic growth and carbon emissions, addressing an important identified gap. To address this gap, annual data from 1992 to 2015 is used. A panel cross-section analysis is provided between countries, and for the seven considered sectors, is estimated through panel corrected standard errors and convergence estimations are presented. Conclusions point to the relocation of pollution-intensive sectors to almost all of the OPEC countries. For all countries, a U-shaped relationship is evidenced, implying that economic growth in oil-producing and exporting countries increases environmental degradation. While energy consumption increases environmental damage, trade openness seems to have a significant and negative effect over emissions, leading to environmental improvements. This study points out that OPEC countries will have increased challenges facing them in terms of environmental degradation and only a few economic activity sectors can conduct environmental improvements through growth. The inclusion of oil prices increased coefficients magnitude. Probably these sectors are already allocating more labour and capital in projects and investments on renewable energy, energy efficiency and energy savings, substituting fossil fuels like oil.