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Air pollution is a serious environmental and health issue that necessitates accurate and timely air-quality monitoring to provide timely health warnings to affected demographics and as a regulatory tool for reduction of emission. Thus, a high-density sensor array was developed for detection and quantification of NO2, SO2, and O3—three contributing air pollutants used for monitoring Air Quality Index (AQI). The gas sensor array operates on the principle of chemiresistive gas sensing with light-tunable selectivity and sensitivity which was achieved by combining the chemical selectivity and photoactive property of macrocyclic compounds with the chemical and electrical sensitivity of semiconducting single-walled carbon nanotubes (SWNTs). More specifically, sensing materials comprising hybrid nanostructures of SWNTs functionalized with either a metallophthalocyanine (MPc) derivative or a metalloporphyrin (MPor) derivative were formulated into printable inks. Each sensor in the array was fabricated by ink-jet printing of sensing materials onto interdigitated platinum electrodes. The sensor array demonstrated tunable sensitivity (in the range of sub-ppm to tens of ppm) to NO2, SO2, and O3 under different combinations of illumination conditions and specific sensing materials.