There are various ways to express the term "background air pollution monitoring network" using different synonyms. One possible alternative is "ambient air quality monitoring system," which refers to a system that regularly checks the air quality in a particular area. Another possible synonym is "surveillance network for air quality," which means a system that tracks the air quality levels of a specific location for a certain period. "Natural air quality monitoring network" is also an option that pertains to monitoring the air quality without any human-made interventions. Other possible synonyms include "passive air quality monitoring network," "background atmospheric monitoring network," and "environmental air quality monitoring network." Regardless of the synonym used, a background air pollution monitoring network is essential for maintaining a healthy environment.