DETROIT — A person briefed on the matter says scientists hired by the auto industry have determined the circumstances that cause Takata air bags to explode violently and kill people.

The person says an announcement from the group is expected Tuesday.

Takata uses ammonium nitrate to create a small explosion and inflate air bags in a crash. Its air bag inflators have caused at least 10 deaths and 139 injuries worldwide.

The person says a number of factors must act in combination to cause the explosion, including but not limited to the presence of moisture that degrades the ammonium nitrate.

The person was not authorized to reveal the findings and didn’t want to be identified.

A Virginia rocket science firm hired by 10 automakers has been running tests to find the cause for the past year.