Aggravated arson is a fairly new term in Pennsylvania. The law creating it as an official offense only came about back in 2014. It was in response to a string of fires that happened in 2008 and 2009. Authorities said that these were set on purpose, and there were more than 30 of them in that short time period.
Typically, arson is just a property crime, as it's done to destroy physical structures and nothing more. Aggravated arson comes into play if there is an intent to harm a person inside the building, or if the arsonist knows that someone is inside and sets the fire anyway. As with standard arson, the fire must be set deliberately. People can also be charged with this if it's discovered that they paid another person to start the fire.
Officials said when the law was passed that arson, under the old laws, usually was a problem just for property owners and insurance companies. It focused on the financial losses and things of this nature. The goal with the new laws was to focus on the real threat to people and the fact that arson could be a deadly crime, not just a property crime.
As you can imagine, it's very important for those being charged with crimes to face the right charges. Getting charged with aggravated arson when simple arson charges are all that apply to the case can massively shift the potential sentence and the impact of that case. All people have a right to a fair trial and to face charges that actually fit the alleged crime, and they must know what to do to protect these rights in Pennsylvania.
Source: The Kelly Law Firm, "Theft & Property Crimes," accessed July 08, 2016