Components used:
-ESP8266 (Node MCU)
-DHT11 (Temperature & Humidity Sensor)
-MQ135 (Gas Sensor for Air Quality)
-BMP180 (Pressure Sensor)
To get the NodeMCU library go to the following link: https://arduino.esp8266.com/Arduino/versions/2.1.0-rc1/doc/installing.html
Then be sure to select NodeMCU V1.0 from the board section in Arduino.
And download Adafruit for BMP180 from Arduino's library management.