Altmetrics are metrics for social media mentions and uses of scholarly output. This data can be useful for monitoring your personal impact with other scholars, practitioners, policy makers and the public.
For a good overview read the following article:
Rise of 'Altmetrics' Revives Questions About How to Measure Impact of Research Chronicle of Higher Education (June 3, 2013)
Not all databases provide this measure. PlumMetrics is the word coined for altmetrics in EBSCO, Science Direct. Below is the record for a search on carbon monoxide from car exhausts and health impact. At the bottom of the record you will see PlumX Metrics.