Air pollution is one of the most dangerous problems we face in the world today. It is the cause of many illnesses like asthma, cancer, bronchitis, congenital disabilities and other diseases that affect the immune system of both humans and non-human animals. Among the factors that characterize the quality of air are temperature and humidity and the level of Carbon dioxide in the environment. This reseaerch involves the design and construction of a device that measures the temperature, humidity and CO2 levels in an environment, using a DHT11 and MQ135 sensor. The values were compared with the expected values from a trusted website to determine the accuracy of the device. The device was also used to take the temperature, humidity and CO2 levels of the living room, bedroom, kitchen and balcony in a house to determine the quality of air in the house. The results obtained in the living room and balcony revealed impressive air quality with the temperature and humidity in the safe zone while the level of CO2 was normal. The air quality in the bedroom was acceptable, although it could do with better ventilation if it is to house more people. The kitchen, however, showed high temperatures at certain hours and high humidity as well as CO2 levels. It was concluded that improvements are necessary for the ventilation of the kitchen to improve the quality of air.