India's rapidly deteriorating air quality driven by urban emissions, agricultural stubble burning, and industrialization has placed 74 of the world's 100 most polluted cities within its borders. This thematic meta-analysis of 30 research (2011-2025) looked at how gaseous pollutants (NO₂, SO₂, O₃, and NOₓ) and particulate matter (PM₂.₅ and PM₁₀) affected mental health at different phases of life. Findings link air pollution to depression, anxiety, cognitive decline, neurodevelopmental impairments, adverse birth outcomes, and dementia, with heightened vulnerability in children, pregnant women, and older adults. Results underscore the urgent need for integrated air quality control and targeted psychosocial interventions.