"Sulfur levels" refers to the amount of sulfur present in a substance or environment. It indicates the concentration or quantity of sulfur that is measured or evaluated. Full definition
A University of Illinois study drawing from over 20 years of data shows that sulfur levels in Midwest watersheds and rivers have steadily declined, so much so that farmers may need to consider applying sulfur in the not too distant future. (sciencedaily.com)
Low sulfur fuels are necessary for cleaner engines (for example high compression diesel engines) and high fuel sulfur levels also interfere with the performance of vehicle emissions control equipment designed to remove small particulates and other pollutants from the exhaust stream (for example particulate filters and catalysts). (ccacoalition.org)
In New York City, which has asthma rates consistently higher than the national average, this bill would reduce sulfur levels from 2,000 parts per million to just 15 parts per million. (politico.com)