In the first time he has spoken to Japanese media, the former engineering manager at Takata Corp. who alerted U.S. authorities to the risks of its air bag inflators said he did so out of a sense of professional and ethical duty.

Mark Lillie said in an interview that blowing the whistle is "very hard." But "if it is a life safety issue ... there is an ethical duty especially for a professional person to come forward even though it might be uncomfortable to do so."

At least 22 deaths and over 180 injuries have been linked to the defective inflators worldwide, which are used by large carmakers such as Honda Motor Co.