Tinnevelly, officially known as Tirunelveli, occupies a strategic position in southern Tamil Nadu, India, nestled at the foothills of the Western Ghats and bordered by the Tamirabarani River that flows through its urban core. Situated at coordinates 8.7136°N, 77.7567°E, this historic city lies approximately 700 kilometres southwest of Chennai, serving as a crucial administrative and commercial hub for the Tirunelveli district. The terrain is predominantly flat with an average elevation of 47 metres above sea level, though it slopes gently towards the southeast where it meets the Gulf of Mannar about 50 kilometres away. This proximity to the coast moderates temperatures but also exposes the city to seasonal maritime influences. The surrounding landscape is a mosaic of urban sprawl, peri-urban settlements, and extensive agricultural zones, particularly paddy fields and banana plantations irrigated by the Tamirabarani, creating a distinct urban–rural gradient. Industrial activity is limited compared to major metros, with small-scale manufacturing, brick kilns, and vehicle emissions constituting the primary pollution sources. The city's location in a relatively sheltered basin, flanked by the Ghats to the west and coastal plains to the east, can trap pollutants under calm wind conditions, especially during the winter months. However, the Tamirabarani River and its associated wetlands provide some natural ventilation, while the absence of heavy industry belts typical of northern India means air quality issues stem more from localised urban activities like construction, transportation, and biomass burning in surrounding rural areas.

Tinnevelly's air quality follows a distinct seasonal rhythm shaped by the region's tropical climate and monsoon patterns. During the winter months from December to February, cooler temperatures and frequent temperature inversions trap pollutants close to the ground, leading to higher particulate matter concentrations, especially in the early mornings when fog can mix with emissions from vehicles and domestic heating. This period poses risks for sensitive groups like asthmatics and the elderly, who should limit outdoor exertion during peak hours. The summer season from March to May brings rising temperatures and dry winds, which can lift dust from construction sites and unpaved roads, though increased convection often disperses pollutants more effectively. The southwest monsoon from June to September dramatically improves air quality, as heavy rains wash away particulates and winds from the Arabian Sea sweep through the region, making this the most favourable time for outdoor activities. Post-monsoon months of October and November see a gradual return of pollution as agricultural residue burning in nearby fields and festive fireworks during Diwali contribute to haze, though coastal breezes still provide some mitigation. Sensitive individuals should monitor local air quality reports during transitional periods and consider using masks on days with visible haze. Overall, the monsoon offers the cleanest air, while winter mornings require caution for vulnerable populations.