What year did fire apparatuses begin to include diesel particulate filters?

Answer: C — 2007

Diesel particulate filters (DPFs) began to be included in fire apparatuses around 2007 as part of a broader initiative to reduce emissions from diesel engines. This change was driven by the need to comply with stricter Environmental Protection Agency (EPA) regulations aimed at decreasing the output of hazardous pollutants, such as particulate matter. The introduction of DPFs marked a significant advancement in engine technology, specifically designed to trap and remove particulate emissions from the exhaust gases, thus improving air quality and environmental safety. The timing aligns with regulatory requirements that prompted manufacturers to adopt cleaner technologies in their vehicles, starting around that year, making 2007 a pivotal moment in fire apparatus development concerning emission control.