Published June 6, 2020 © GPL3+

IoT Based Air Quality Index Monitoring with MQ135 & ESP8266

We will monitor the air quality index in PPM using MQ135 Air Quality Sensor & ESP8266. The logged data will ca be observed in Thingspeak.

IntermediateFull instructions provided3 hours9,736

IoT Based Air Quality Index Monitoring with MQ135 & ESP8266

Story

The AQI is an index that tells you how clean or polluted your air is, and what associated health effects might be a concern for you.

The level of pollution has increased with times by a lot of factors like the increase in population, increased vehicle use, industrialization, and urbanization which results in harmful effects on humans by directly affecting the health of the population exposed to it. So, we need to monitor the Air Quality Index. In this project, we are going to make an IoT Based Air Quality Index Monitoring System in which we will monitor the Air Quality Index over a Thingspeak server using the internet. We will use MQ135 Air Quality Sensor that can detect the level of various air pollutants.

Air Quality Index

The AQI is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air.

Think of the AQI as a yardstick that runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 represents good air quality with little potential to affect public health, while an AQI value over 300 represents hazardous air quality.

Circuit Diagram & Connections

Now let us assemble the hardware and do the coding for the great IoT project. We will interface MQ135 Air Quality Sensor with NodeMCU ESP8266 Board and 0.96″ I2C OLED Display. The circuit diagram is given below.

You can assemble the circuit in a breadboard. First, connect the MQ135 Analog input pin to A0 of NodeMCU. Then connect its VCC and GND to NodeMCU Vin & GND respectively. Similarly, 0.96″ OLED Display is an I2C Module. So, connect its SDA & SCL Pin to Nodemcu D2 & D1 Pins. Connect its VCC to 3.3V GND to GND.

Setting up Thingspeak

ThingSpeak is an open-source Internet of Things application and API to store and retrieve data from things using the HTTP and MQTT protocol over the Internet or via a Local Area Network. Thingspeak enables you to collect, store, analyze, visualize, and act on data from sensors.

To set up the Thingspeak Server, visit https://thingspeak.com/ . Create an account or simply sign in if you created the account earlier. Then create a new channel. Copy the API key and use it in the code below.

Results

To learn in more detail about this project, you can visit my official website Article Link: https://how2electronics.com/iot-air-quality-index-monitoring-esp8266/

Code

Air Quality Index Monitoring Code

#include <ESP8266WiFi.h>
#include <SPI.h>
#include <Wire.h>
#include "MQ135.h"
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128    // OLED display width, in pixels
#define SCREEN_HEIGHT 64    // OLED display height, in pixels
#define OLED_RESET -1       // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

String apiKey = "********"; // Enter your Write API key from ThingSpeak
const char *ssid = "**********";     // replace with your wifi ssid and wpa2 key
const char *pass = "**********";
const char* server = "api.thingspeak.com";

WiFiClient client;


void setup()
{
  Serial.begin(115200);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); //initialize with the I2C addr 0x3C (128x64)
  display.clearDisplay();
  delay(10);

  Serial.println("Connecting to ");
  Serial.println(ssid);
  
  display.clearDisplay();
  display.setCursor(0,0);  
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.println("Connecting to ");
  display.setTextSize(2);
  display.print(ssid);
  display.display();
  
  WiFi.begin(ssid, pass);

  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
    Serial.println("");
    Serial.println("WiFi connected");
    
    display.clearDisplay();
    display.setCursor(0,0);  
    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.print("WiFi connected");
    display.display();
    delay(4000);
}


  void loop()
  {
    MQ135 gasSensor = MQ135(A0);
    float air_quality = gasSensor.getPPM();
    Serial.print("Air Quality: ");  
    Serial.print(air_quality);
    Serial.println("  PPM");   
    Serial.println();

    display.clearDisplay();
    display.setCursor(0,0);  //oled display
    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.println("Air Quality Index");
    
  
    display.setCursor(0,20);  //oled display
    display.setTextSize(2);
    display.setTextColor(WHITE);
    display.print(air_quality);
    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.println(" PPM");
    display.display();


    if (client.connect(server, 80)) // "184.106.153.149" or api.thingspeak.com
  {
    String postStr = apiKey;
    postStr += "&field1=";
    postStr += String(air_quality);
    postStr += "r\n";
    
    client.print("POST /update HTTP/1.1\n");
    client.print("Host: api.thingspeak.com\n");
    client.print("Connection: close\n");
    client.print("X-THINGSPEAKAPIKEY: " + apiKey + "\n");
    client.print("Content-Type: application/x-www-form-urlencoded\n");
    client.print("Content-Length: ");
    client.print(postStr.length());
    client.print("\n\n");
    client.print(postStr);
    
    Serial.println("Data Send to Thingspeak");
  }
    client.stop();
    Serial.println("Waiting...");

    delay(2000);      // thingspeak needs minimum 15 sec delay between updates.
}

Credits

Mamtaz Alam

1 project • 4 followers

I am passionate about Latest Electronics Innovations & advancement in the field of Arduino, Internet of Things & Power Electronics Design.

IoT Based Air Quality Index Monitoring with MQ135 & ESP8266