Industry experts have speculated that a particular chemical propellant used in airbags may be the cause of the recent string of Takata airbag problems.

Takata manufactured airbags for a wide range of car companies. Because of this, Takata’s recall has affected nearly 8 million vehicles across different brands. Allegedly, problems with Takata airbags have caused at least 30 accidents, and four deaths.

While the lion’s share of the recall has impacted Honda vehicles, Toyota and General Motors both have models among the recalled vehicles. In total, more than 50 models of cars have been recalled because they used Takata airbags.

Investigations are ongoing, and still in their early phases. However, according to Bloomberg News, Takata uses an usual chemical explosive to deploy their airbags, which may be the cause or a contributing factor to the “exploding airbags” problems.

Unlike most airbags, Takata used a chemical called ammonium nitrate in its airbags. In larger portions, ammonium nitrate is used in 80 percent of commercial and military explosives in the United States. It was also used in the Oklahoma City bombing, as well as other terrorist attacks around the world.

Additionally, many of the largest industrial disasters in U.S. history have been linked to ammonium nitrate detonations, since the chemical is also widely stockpiled and used in fertilizer as well as explosives. This unusual choice was actually more expensive than the explosive used in conventional airbags.

It is believed that using ammonium nitrate could allow Takata to build smaller and lighter air bags by using a very small, theoretically controlled, portion of the chemical.

However, others have suggested other possible causes or contributing factors. For example, experts at Toyota suggested that lapses in quality control may have been another possible explanation for some of the exploding airbags.

In a statement to the press, Takata’s chairman, Shigehisa Takada, apologized, assuring customers and shareholders that his company was working “night and day” trying to correct the problem.

Several class action lawsuits have been filed against Takata and automakers over the alleged problems with Takata airbags. These lawsuits allege that Takata, or the automakers who used Takata airbags, were aware — or reasonably should have been aware — of the risk of exploding airbags. These lawsuits further allege that in spite of this, Takata did not issue a recall soon enough, endangering the lives of passengers driving vehicles bearing their airbags.