A whif here, a whif there; pretty soon you're talking about a real stink

'Upset' emissions: Flares in the air, worry on the ground | The Center for Public Integrity:

"Dr. Mark D’Andrea, at the University of Texas Cancer Center, began tracking 4,000 residents exposed to the poster child of all upsets — the “40-day Release” at the BP refinery, in Texas City, which belched 514,795 pounds of benzene and 20 other pollutants throughout the spring of 2010."

"Upset" is industry parlance for "unplanned emission," sort of like "unpleasantness" for "war." But that would be just splitting hairs.