code.ino

#define BLYNK_TEMPLATE_ID "TMPLgwKssgggsnFXp"
#define BLYNK_DEVICE_NAME "Air Quality Monitoring"
#define BLYNK_AUTH_TOKEN "k03gT6nJosdsfsffesrJV_S5SXEAdgdsdghhgPZvXEwSKDfj"

#define BLYNK_PRINT Serial
#include <ESP8266WiFi.h> 
#include <BlynkSimpleEsp8266.h>

#include <DHT.h>

//#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

  byte degree_symbol[8] = 
              {
                0b00111,
                0b00101,
                0b00111,
                0b00000,
                0b00000,
                0b00000,
                0b00000,
                0b00000
              };
              
char auth[] = BLYNK_AUTH_TOKEN;

char ssid[] = "";  // type your wifi name
char pass[] = "";  // type your wifi password

BlynkTimer timer;

int gas = A0;
int sensorThreshold = 100;

#define DHTPIN 2 //Connect Out pin to D2 in NODE MCU
#define DHTTYPE DHT11  
DHT dht(DHTPIN, DHTTYPE);


void sendSensor()
{


  float h = dht.readHumidity();
  float t = dht.readTemperature(); // or dht.readTemperature(true) for Fahrenheit
 

     if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }
   int analogSensor = analogRead(gas);
  Blynk.virtualWrite(V2, analogSensor);
  Serial.print("Gas Value: ");
    Serial.println(analogSensor);
  // You can send any value at any time.
  // Please don't send more that 10 values per second.
    Blynk.virtualWrite(V0, t);
    Blynk.virtualWrite(V1, h);
   
    Serial.print("Temperature : ");
    Serial.print(t);
    Serial.print("    Humidity : ");
    Serial.println(h);
    
 
}
void setup()
{   
  
  Serial.begin(115200);
  
 //pinMode(gas, INPUT);
  Blynk.begin(auth, ssid, pass);
  dht.begin();
  timer.setInterval(30000L, sendSensor);

 //Wire.begin();
   lcd.begin();


//  lcd.backlight();
 // lcd.clear();
  lcd.setCursor(3,0);
  lcd.print("Air Quality");
  lcd.setCursor(3,1);
  lcd.print("Monitoring");
  delay(2000);
  lcd.clear();
  }

void loop()
{
  Blynk.run();
  timer.run();
 float h = dht.readHumidity();
  float t = dht.readTemperature(); // or dht.readTemperature(true) for Fahrenheit
    int gasValue = analogRead(gas);
  lcd.setCursor(0,0);
  lcd.print("Temperature "); 
  lcd.setCursor(0,1);
  lcd.print(t);
  lcd.setCursor(6,1);
  lcd.write(1);
  lcd.createChar(1, degree_symbol);
  lcd.setCursor(7,1);
  lcd.print("C");
  delay(4000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Humidity ");
  lcd.print(h);
  lcd.print("%");
  delay(4000);
  lcd.clear();
  //lcd.setCursor(0,0);
 // lcd.print(gasValue);
 // lcd.clear();
  if(gasValue<600)
  {
    lcd.setCursor(0,0);
    lcd.print("Gas Value: ");
    lcd.print(gasValue);
    lcd.setCursor(0, 1);
    lcd.print("Fresh Air");
    Serial.println("Fresh Air");
    delay(4000);
    lcd.clear();
  }
  else if(gasValue>600)
  {
    lcd.setCursor(0,0);
    lcd.print(gasValue);
    lcd.setCursor(0, 1);
    lcd.print("Bad Air");
    Serial.println("Bad Air");
    delay(4000);
    lcd.clear();
  }

   if(gasValue > 600){
    //Blynk.email("youremail@gmail.com", "Alert", "Bad Air!");
    Blynk.logEvent("pollution_alert","Bad Air");
  }
 }