Air pollution contains sulfur dioxide (SO₂) of 31.1%, nitrogen dioxide (NO₂) of 27.2%, carbon oxide (CO_x) of 16.8%, and mineral particles of 6.3% according to the ministry of environment, Korea. Since air pollution has been harmfully affecting the health of people, the importance of controlling gas concentration and air pollution have been increased greatly and socially. To measure those gases the conventional gas detectors used by ultraviolet (UV) absorption method cannot display the image for total distribution of the gas and use public in daily life. In addition, the gas detectors used mainly at coal-fired power plant are installed in the chimney and a length of detecting probe in a detector is about 1 to 2 meters, which analyze quantitatively the gas passing through the hole with a diameter of 5-10 cm. Furthermore, since the conventional gas detectors measure only a small amount of gas coming out from chimney and their accuracies are not precise, thus, the more precise method is required for measuring the emitted gas quantitatively. In this study, therefore, we propose ultraviolet CMOS image sensor (UV-CIS) which can detect NO₂ and SO₂ gases quantitatively to enhance the sensitivity in detecting such gases. In particular, we investigated the characteristics of UV-CIS. We fabricated the UV-CIS embedded with blue-light emitting QD films. The structure of the UV-CIS consists of blue QDs film and blue color filter placed on conventional Si-CIS. The fabricated UV-CIS demonstrated much higher sensitivity in detecting both NO₂ and SO₂ gases at whole range of concentrations than conventional CIS. In particular, the sensitivity of the UV-CIS increased 1.9 times higher in detecting NO₂ and 9.4 times higher in detecting SO₂ than conventional CIS, respectively. It was conformed that the QD film converted UV into visible light through energy-down-conversion mechanism, which led to enhancing a sensitivity to UV light in CIS. Finally, we present energy-down-conversion characteristics of QDs synthesized, UV absorption characteristics of NO₂ and SO₂ gases, and the mechanism on sensing UV-light of UV-CIS to analyze an air environment.