Air pollution remains a major global issue that seriously impacts public health, environmental quality, and ultimately human health. To help monitor problem, we have created and constructed a low-cost, real-time, portable air quality monitoring system using cheap sensors. The system measures critical pollutants PM2.5, PM10, and carbon monoxide (CO), and environmental variables such as temperature and humidity. The system computes the Air Quality Index (AQI) and transmits the data via a Bluetooth connection. The data is relayed, in real time, to a mobile application. Because of its small size and low manufacturing cost the system readily lends itself to indoor and outdoor use and in urban and rural environments. In this paper we give an account of the system design, development, and validation, while demonstrating its accuracy and low-cost capabilities. We also consider its wider environmental, social, and regulatory implications with regards to; improving public awareness, being used for sustainability purposes and providing valuable information for informed decision making.