Air Quality Monitoring Made Easy: An IoT Project with ESP32

This project demonstrates a practical approach to air quality monitoring using affordable hardware and MQTT for data transmission.

IntermediateShowcase (no instructions)6 hours2,927

Air Quality Monitoring Made Easy: An IoT Project with ESP32

Things used in this project

Hardware components

Seeed Studio XIAO ESP32S3 Sense

DFRobot DHT22 Temperature and Humidity Sensor

Seeed Studio Grove - Air quality sensor v1.3

DFRobot Gravity: Analog CO2 Gas Sensor For Arduino

PHPoC Bread Board

Jumper wires (generic)

Software apps and online services

MQTT

PlatformIO IDE

Story

The Crucial Importance of Monitoring Air Quality

Air, the very essence of life, is often taken for granted. We breathe it in without a second thought, unaware of the invisible battle raging within it. This battle involves pollutants, harmful substances that can wreak havoc on our health and environment.

Why monitor air quality?

Monitoring air quality is crucial for several reasons:

1. Protecting Public Health:

Poor air quality is linked to a multitude of health problems, including:

Respiratory issues: Asthma, bronchitis, and even lung cancer can be exacerbated by exposure to pollutants like ozone and particulate matter.
Cardiovascular diseases: Air pollution can contribute to heart disease, stroke, and high blood pressure.
Cognitive decline: Studies have shown a link between air pollution and decreased cognitive function, memory loss, and dementia.
Premature death: The World Health Organization estimates that 7 million people die prematurely each year due to air pollution

2. Environmental Impact:

Air pollution not only harms humans but also damages the environment. It can:

Contribute to climate change: Certain pollutants, like greenhouse gases, trap heat in the atmosphere, accelerating global warming.
Harm ecosystems: Acid rain, caused by sulfur dioxide and nitrogen oxides, can damage forests and lakes.
Reduce visibility: Smog, a mixture of air pollution and fog, can decrease visibility, leading to accidents.

3. Informing Policy and Action:

By monitoring air quality, we can identify pollution sources, track trends, and assess the effectiveness of pollution control measures. This information is essential for policymakers to develop and implement effective strategies to improve air quality.

How is air quality monitored?

Air quality is monitored using a network of sensors that measure various pollutants, such as ozone, particulate matter, sulfur dioxide, and nitrogen oxides. These sensors are often located in strategic places, such as near industrial facilities, major roads, and urban centers.

The data collected from these sensors is then transmitted to a central location, where it is analyzed and used to generate air quality reports and forecasts. This information is then made available to the public through various channels, such as websites, mobile apps, and air quality alerts.

This project empowers you to build a cost-effective, DIY air quality monitoring system that leverages the versatility of the ESP32 board and the power of MQTT for remote data access.

Materials:

ESP32 development board
DHT22 temperature and humidity sensor
Air quality sensor (e.g., MQ135, CCS811, or other suitable sensor)
CO2 sensor (e.g., MH-Z19B)
Breadboard and jumper wires
MQTT broker (e.g., Mosquitto, HiveMQ, or cloud-based options)

Wiring:

Connect the DHT22 sensor:

VCC to 3.3V
Data pin to GPIO 4
GND to GND

Connect the air quality sensor (example based on MQ135):

VCC to 5V
AOUT to ADC pin (e.g., GPIO 35)
GND to GND
Connect the air quality sensor (example based on MQ135): - VCC to 5V - AOUT to ADC pin (e.g., GPIO 35) - GND to GND
Connect the CO2 sensor (example based on MH-Z19B):
VCC to 5V
TX to RX pin (e.g., GPIO 16)
RX to TX pin (e.g., GPIO 17)
GND to GND

Arduino IDE program

#include <WiFi.h>
#include <PubSubClient.h>
#include <DHT.h>
#include <MQUnifiedsensor.h>

// Replace with your WiFi credentials and MQTT broker details
const char* ssid = "your_WiFi_SSID";
const char* password = "your_WiFi_password";
const char* mqtt_server = "your_MQTT_broker_address";

// Define sensor pins and variables
#define DHTPIN 4
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

MQUnifiedsensor mq135(board, A0, "MQ-135"); // Adjust board type and analog pin if needed

// CO2 sensor object (adjust library and pin configuration if using a different sensor)
MH_Z19B mhz19b;

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  // Initialize serial, WiFi, MQTT, sensors
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  client.setServer(mqtt_server, 1883);
  dht.begin();
  mq135.setRegressionMethod(1); // Set regression method for air quality sensor
  mhz19b.begin(); // Initialize CO2 sensor
}

void loop() {
  // Connect to WiFi and MQTT broker
  reconnect();
  client.loop();

  // Read sensor values
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();
  float airQuality = mq135.readSensor();
  int co2Level = mhz19b.getCO2();

  // Publish sensor data to MQTT topics
  client.publish("sensor/temperature", String(temperature).c_str());
  client.publish("sensor/humidity", String(humidity).c_str());
  client.publish("sensor/airquality", String(airQuality).c_str());
  client.publish("sensor/co2", String(co2Level).c_str());

  delay(5000); // Delay between readings
}

void reconnect() {
  while (!client.connected()) {
    // Attempt to connect to MQTT broker
  }
}