The poor state of air quality all over the world in general, and across India in particular, is a cause for extreme concern as it is directly and indirectly linked to the deterioration of human health and economies of nations The many complexities and challenges posed by ambient air quality monitoring, prompted the World Health Organization (WHO) to suggest a road map for all nations for the year 2020 -to arrive at a consensus for effective air quality monitoring by all stakeholders – nations and governments, regulatory and controlling bodies, NGOs, scientists and researchers and private citizens.As we approach the end of 2021, the multifaceted and multidimensional problems related to effective ambient air quality monitoring still remain herculean, and extremely expensive for wider deployment to gather a realistic spatiotemporal information related to ambient air quality, in order to draw up effective plans to curb or mitigate the air pollution. The complexities for effectively monitoring ambient air quality led to confusing practices in selection of sensors and systems for air quality monitoring, the siting of systems, and the empirical approaches followed by different stakeholders in arriving at averaging times related to expensive systems for measurements, resulted in different definitions of air quality. Today, the confusion is worse confounded with the advent of new entrants into the field advocating low cost sensors with lesser accuracies for niche applications. Against this backdrop the present two-part paper highlights the impetus, complexities and challenges posed for ambient air quality monitoring in the first part of the paper. The second part of the paper introduces a novel indigenously developed state of art photonic system for ambient air quality monitoring having higher accuracies with overarching capabilities for diverse applications.A unique calibration facility designed and developed for the indigenous photonic system ensures that after a onetime calibration the system can be deployed for field usage anywhere in the world under any extreme weather conditions. AUM was compared with the conventional imported ambient air quality monitoring stations and found to be far superior in characteristics.The indigenously designed and developed system, called as AUM (Air Unique-quality Monitoring) is extremely economical compared to the conventional standard reference stations, thus making it ideal for large scale deployment to effectively monitoring the hitherto eluded spatio temporal variations of ambient air quality.