Abstract
Fire accidents and hazardous gas leakage are major causes of loss of life and property, especially in residential, industrial, and commercial environments. To address this problem, this project presents an IoT-based Fire Detection and Alert System using NodeMCU (ESP8266), Fire sensor, MQ-135 gas sensor, Buzzer, Blynk platform, and a receiver-side NodeMCU with LCD and LED indicators.
The transmitter-side NodeMCU continuously monitors environmental conditions by sensing flame intensity and harmful gases such as smoke, carbon dioxide, and ammonia using the fire sensor and MQ-135 sensor. When abnormal conditions indicating fire or gas leakage are detected, the system immediately activates a buzzer for local alert and sends real-time notification data to the Blynk IoT application through Wi-Fi.
At the receiver side, another NodeMCU receives the alert data wirelessly and displays the fire and gas status on an LCD while simultaneously activating LEDs to provide clear visual indication of danger. This dual-alert mechanism ensures quick response even if mobile notifications are missed.
The proposed system is cost-effective, reliable, and easy to implement, making it suitable for smart homes, industries, warehouses, and public safety applications. By integrating IoT technology with real-time monitoring and alert mechanisms, the system enhances safety and minimizes fire-related risks.
Introduction
Fire hazards and toxic gas leakage pose serious threats to human life, property, and the environment. Accidental fires in homes, industries, laboratories, and commercial buildings can lead to severe damage if they are not detected at an early stage. Traditional fire detection systems often lack real-time monitoring, remote alert capabilities, and intelligent decision-making, which can delay emergency response.
With the rapid growth of the Internet of Things (IoT), smart monitoring systems have become more reliable and efficient for safety applications. IoT enables sensors and devices to communicate through the internet, allowing real-time data monitoring, analysis, and instant alert generation. By integrating IoT technology with fire and gas sensors, it is possible to design a smart fire detection system that provides faster response and improved safety.
This project focuses on the design and implementation of an IoT-based Fire Detection System using NodeMCU. The system uses a fire sensor to detect flames and an MQ-135 gas sensor to identify harmful gases and smoke. When a fire or gas leakage is detected, a buzzer provides immediate local alert, and notifications are sent to users through the Blynk IoT platform. Additionally, a receiver-side NodeMCU displays alert information on an LCD and activates LED indicators for clear visual warning.
The proposed system is low-cost, easy to install, and suitable for applications such as smart homes, industries, warehouses, and public safety environments. By providing early detection and real-time alerts, the system helps in reducing fire-related risks and improving overall safety.

Objectives
1. To detect fire using a fire sensor.
2. To detect smoke and harmful gases using the MQ-135 sensor.
3. To give an alert using a buzzer during fire or gas detection.
4. To send warning notifications through the Blynk IoT application.
5. To display alert information on LCD and LED using receiver-side NodeMCU.
6. To improve safety by early fire detection using IoT technology.