As of 2018, 33.2% of the Indian population resides in urban areas. Hence, the expansion of cities has led to an increase in automobiles, industrial production, and rapid deforestation. Consequently, air pollution and environmental deterioration have reached an alarming stage. One of the fundamental features of smart cities is providing a sustainable environment. Rapid urbanization and industrialization have made it quintessential to monitor the environmental parameters. The major problem in environmental monitoring is real-time data acquisition through durable and accurate monitoring equipment. Hence, Compact Air Quality Monitoring Sensors play an important role in Environmental Monitoring for Smart cities.