By combining detailed chemical measurements in the deep ocean, in the oil slick, and in the air, NOAA scientists and academic colleagues have independently estimated how fast gases and oil were leaking during the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. The new chemistry-based spill rate estimate, an average of 11,130 tons of gas and oil compounds per day, is close to the official average leak rate estimate of about 11,350 tons.