Website-Based Air Quality Monitoring Design (CO, C0₂, N0₂) With Smartphone Push Notification

Air pollution poses a significant health concern in major cities worldwide, affecting all age groups, including infants, adolescents, and pregnant women. The World Health Organization has linked air pollution to increased risks of stroke, heart disease, chronic obstructive pulmonary disease, lung cancer, pneumonia, and cataracts. Despite the awareness of these risks, real-time data on air quality is often lacking, necessitating systems that provide this information to prevent excessive exposure. In our study, we developed an online IoT-based air quality monitoring system that sends data to a database and displays it on a website, complemented by an offline TFT LCD system. The system measures CO, CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>, NO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>levels, temperature, and humidity, and includes an early warning system that activates based on specific thresholds. Sensor accuracy was a key focus: the MQ9 sensor had an accuracy of 82.29%, the MQ7 sensor 87.37%, the MG811 sensor 95.07%, and the NDIR sensor 97.40<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup>. The DHT22 sensor showed high accuracy for temperature and humidity, close to the validator values. Performance testing of both tools in two different locations showed an average delay of 3 to 7 seconds between online (website) and offline (LCD) monitoring due to internet connectivity issues. Additionally, smartphone push notifications were successfully sent during very polluted events and at scheduled times via WhatsApp.