What is the sulfur content in natural gas?

From EPA website:

Emissions of SO2 from natural gas-fired boilers are low because pipeline quality natural gas typically has sulfur levels of 2,000 grains per million cubic feet.

However, sulfur-containing odorants are added to natural gas for detecting leaks, leading to small amounts of SO2 emissions. Boilers combusting unprocessed natural gas may have higher SO2 emissions due to higher levels of sulfur in the natural gas. For these units, a sulfur mass balance should be used to determine SO2 emissions.

P.S. 7,000 grains = 1 pound so in 1 million cubic feet of natural gas there would typically be 0.286 lbs of sulfur.