This study evaluates the impact of author self-citations on h index by exploring 583 authors whose works appear in key periodicals in environmental engineering. The findings show that authors’ h values have high correlation with authors’ article number, total cited count, and their rankings. There is also a high correlation with h index values and rankings of h values. The study indicates that elfcitations
have little impact on the values of h index and the h index rankings, whether or not articles with authors’ self-citation are
included. Further investigations reveal that, for authors with high values in h index, the two h index values are both highly correlated and with significant difference either with self-citations or without. A similar pattern is seen in authors with low h values. The results
suggest that there is no need to deliberately exclude self-citations in analysing or evaluating research performance in environmental engineering.