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Nestled in the Krishnagiri district of Tamil Nadu, Hosur occupies a strategic position at the border with Karnataka, approximately 40 kilometres southeast of Bangalore, making it a critical node in the Bengaluru-Chennai industrial corridor. Situated at an elevation of 880 metres above sea level on the Deccan Plateau, the city's terrain is characterised by undulating hills and rocky outcrops, with the Hosur plateau forming part of the Eastern Ghats foothills. This elevated setting, while offering moderate temperatures, creates a basin-like effect that traps pollutants, particularly during cooler months. The city lies near the Palar River basin, though water bodies are sparse, contributing to dust issues. Hosur's geography has catalysed its transformation from an agricultural hub—surrounded by mango orchards and farmland—into a bustling industrial centre, anchored by the State Industries Promotion Corporation of Tamil Nadu (SIPCOT) industrial complex and electronics parks. This urban–rural gradient sees rapid construction and vehicular influx, especially from Bangalore-bound traffic, exacerbating air quality challenges. The region's proximity to the Eastern Ghats influences local wind patterns, which can disperse or concentrate emissions depending on seasonal shifts, while the lack of major water bodies limits natural cleansing of airborne particulates.

Hosur's tropical wet-and-dry climate shapes a distinct seasonal air quality narrative, with pollution peaking from November to February during the dry winter months. This period sees cooler temperatures and frequent temperature inversions, where a layer of warm air traps pollutants near the surface, compounded by calm winds and morning fog that hinder dispersion. Industrial emissions from SIPCOT, vehicular exhaust from the busy Bangalore corridor, and construction dust accumulate, making these months particularly hazardous for outdoor activities; sensitive groups like children, the elderly, and those with respiratory conditions should limit exposure and use masks. The summer months from March to May bring extreme heat, which can increase ozone formation from industrial and vehicular precursors, though occasional pre-monsoon winds offer some relief by scattering pollutants. The southwest monsoon from June to September ushers in heavy rainfall that scrubs the air, leading to the cleanest conditions—ideal for outdoor pursuits—as rains suppress dust and wash away particulates. However, post-monsoon months in October see a gradual return of pollution as dry weather resumes, with agricultural residue burning in surrounding areas occasionally adding to the mix. Year-round, diesel generators during power outages and ongoing construction contribute to baseline pollution, necessitating vigilance for asthma and heart disease sufferers.