Nagapattinam occupies a distinctive coastal position in Tamil Nadu's fertile Cauvery Delta region, situated on the Coromandel Coast where the Bay of Bengal meets the flat alluvial plains of eastern India. This port city lies at near-sea-level elevation, with its urban core extending just 1-2 meters above mean sea level, creating a landscape dominated by water bodies, canals, and brackish lagoons that influence local microclimates. The city serves as both an administrative hub and a critical marine gateway, with its deep-water port facilitating shipping activities that contribute directly to air quality challenges. Surrounding Nagapattinam, the landscape transitions rapidly from urbanized port areas to intensive paddy cultivation zones, creating an urban-rural gradient where agricultural emissions from crop residue burning mingle with urban pollution sources. The city's position on a low-lying coastal plain means it lacks topographical barriers to disperse pollutants, while its proximity to the Bay of Bengal subjects it to sea breezes that can alternately dilute or transport marine emissions inland. This geography places Nagapattinam at the intersection of maritime industrial activity, agricultural heartland, and traditional fishing communities, with each sector contributing distinct particulate and gaseous emissions that accumulate in the region's humid tropical atmosphere. The city's location within India's southeastern industrial corridor further connects it to regional pollution transport patterns, particularly during the northeast monsoon when winds carry emissions from more industrialized areas toward the coast.

Nagapattinam's air quality follows a pronounced seasonal rhythm dictated by the region's tropical wet-and-dry climate and monsoon patterns. During the northeast monsoon season from October to December, the city experiences its cleanest air as frequent rainfall scrubs pollutants from the atmosphere, though this period coincides with cyclone risks that can temporarily suspend normal pollution patterns. The post-monsoon months of November through February mark Nagapattinam's peak pollution season, when calm winds, lower temperatures, and frequent temperature inversions trap emissions from port operations, diesel generators, and agricultural burning across the stable atmospheric layer. This period sees particularly hazardous conditions in December and January when crop residue burning in surrounding paddy fields coincides with festive fireworks and increased generator use during power outages. Sensitive groups including children, elderly residents, and those with respiratory conditions should minimize outdoor exposure during morning hours when inversion layers are strongest and pollution concentrations peak. The summer months from March to May bring extreme heat that accelerates photochemical reactions, transforming primary emissions into secondary pollutants, though stronger sea breezes provide some dispersion relief. The southwest monsoon from June to September offers the most favorable conditions for outdoor activity, with consistent winds and precipitation significantly improving air quality despite high humidity. Throughout the year, residents should monitor local wind patterns, as offshore flows can concentrate port emissions over the city while onshore breezes provide temporary relief.