BOSTON (AP) ‚ÄĒ The family of an electrician who died in a July 2010 propane¬†explosion has settled a lawsuit against a propane distributor and a plumbing company for $7.5 million.

Lawyers for the family of the late William Nichols and two people who suffered permanent injuries in the blast at a Norfolk condominium project said Monday that the combined cases settled last week for a total of $22.5 million.

The explosion also led to newly proposed Massachusetts regulations focused on propane safety.

Nichols' lawsuit alleged that EnergyUSA Propane under-filled a new propane tank causing the chemical odorant which had been added to it to fade. This made the leaking propane odorless and undetectable.

Fire investigators also found the propane in the partly-full 1,000-gallon underground storage tank that exploded had "virtually no Ethyl Mercaptan," the additive whose smell alerts people to a leak.

The lawsuit also alleged Smolinsky Brothers Plumbing and Heating failed to tighten a connection that led to the leak at the construction site. No one returned a phone message left Monday at the plumbing company.

On Monday, EnergyUSA Propane's phone line had a recording saying Osterman Propane acquired its assets and affiliates in February. But that company's manager Vincent Osterman said Monday that the lawsuit "stayed with the predecessor company and they settled it."

Nichols suffered burns over 80 percent of his body. It took firefighters more than 90 minutes to dig the 46-year-old Blackstone resident out of the rubble, and he died that night in a Boston hospital.

The electrician was engaged to be married, did volunteer work for a veterans' organization, and played guitar in a band. His brother, 51-year-old Mark Nichols of Bellingham, Mass., said Monday that the settlement has sparked mixed emotions as loved ones continued to grieve.

"It's been getting better as time goes by but sometimes I'll hear a song on the radio and say 'I'll never see him perform that song again,'" he said.

But Nichols said the safety changes expected to come out of the incident would have pleased his brother.

"He'll be dancing in the heavens if this goes through, for him to know that he didn't die in vain," he said.

State fire officials said that by working to trace the origin of the propane from the explosion, they found that the distribution of un-odorized or under-odorized propane was a problem in Massachusetts and possibly other states.

State Fire Marshal Stephen Coan said Monday he's encouraged federal officials to study the problem and put national regulations in place. In the meantime, Massachusetts officials expect to soon add new regulations to state code aimed at making sure propane is odorized before it gets to distribution chains and at solving odorant fade issues at the consumer level.