Combining these characters gives you 消 (eliminate) + 防 (prevent) + 员 (member) — literally “a member who eliminates and prevents [fires].” It's a perfect and descriptive name for the role.
In Chinese culture, 消防员 (xiāofángyuán) are held in extremely high regard, often viewed as national heroes. Their social status is comparable to soldiers, and in fact, China's firefighting force is part of the People's Armed Police (武警, wǔjǐng), a paramilitary organization. This imbues the role with a sense of national duty, discipline, and self-sacrifice that is deeply respected. A powerful modern term that captures this sentiment is 最美逆行者 (zuì měi nìxíngzhě), which translates to “the most beautiful retrogrades” or “the most beautiful people going against the flow.” This poetic phrase refers to first responders, especially firefighters, who run into a dangerous situation (fire, earthquake, flood) while everyone else is running away. This contrasts slightly with Western culture. While firefighters are universally respected in the West, the “hero” status is often localized and community-based. In China, the heroism of a 消防员 is tied more explicitly to a sense of national service and collective sacrifice. The term 最美逆行者 is a uniquely popular and poignant Chinese expression that highlights the societal value placed on putting the group's safety before one's own.
消防员 (xiāofángyuán) is a standard, neutral-to-formal term used across all situations. There isn't a separate slang or informal word for it.