Fig. 2From: Improving the performance of spray operators through monitoring and evaluation of insecticide concentrations of pirimiphos-methyl during indoor residual spraying for malaria control on Bioko IslandComparison of residual concentrations by room and surface between operations. The average concentrations of pesticide residuals are presented in a box and whisker plot by room (bedroom or living room) and operation periods (1 for March and 2 for June) by surface type (concrete or wood)Back to article page