Measuring Air Pollution With Arduino: A Beginner's Guide

Air pollution is a pressing issue that has massive consequences for our health and quality of life. While we often think of smog-filled cities and power plants churning out harmful emissions, it's also important to consider the air pollution that occurs within our homes. With tools like Arduino, it is possible to build a DIY air quality monitoring system to improve the air quality in your home and create a safer and healthier environment. In this article, we will discuss how to measure air pollution using an Arduino board and various sensors to detect parameters such as gas levels, temperature, humidity, and particulate matter.

Using an MQ135 sensor to detect various gases

The MQ135 is a semiconductor air quality check sensor that can be used to detect and measure a wide range of gases, including NH3 (ammonia), NOx, CO2, benzene, smoke, and other dangerous gases in the atmosphere. It is highly sensitive to these gases and has a low cost, making it a good choice for a variety of applications.

MQ135 sensors are available as a module or as just the sensor alone. If you are trying to detect the presence of a gas without measuring its PPM, you can buy it as a module since it comes with an op-amp comparator and a digital output pin. However, if you plan to measure the PPM of a gas, it is recommended to buy the sensor alone without the module. The MQ135 sensor module comes with a Digital Pin, which allows the sensor to operate even without a microcontroller when detecting a particular gas. To measure the gases in PPM, the analog pin needs to be used.

To use the MQ135 sensor, simply power the module with 5V and you will notice the power LED on the module glow. When no gas is detected, the output LED will remain turned off, indicating that the digital output pin is at 0V. It is important to note that these sensors require a pre-heating time of about 20 seconds to 1 minute before they can be used to ensure accurate output. Once the sensor is introduced to the gas you want to detect, the output LED will go high, along with the digital pin. If the output remains low, adjust the potentiometer until the output increases. Every time the sensor detects this particular gas concentration, the digital pin will go high (5V), and if it doesn't detect the gas, the pin will remain low (0V). You can also use the analog pins to get the same results. The output analog values (0-5V) are read from the microcontroller and are directly proportional to the gas concentration detected by the sensor.

The MQ135 gas sensor uses tin dioxide (SnO2) as its gas-sensing material, which has low conductivity in clean air. When there is an increase in polluting gases, the conductivity and sensitivity of the sensor increase with the concentration of the polluted gas in the air. To measure PPM using the MQ135 sensor, you can refer to the (Rs/Ro) vs PPM graph from the MQ135 datasheet, which shows the typical sensitivity characteristics of the sensor for several gases.

Measuring PM2.5 or particulate matter in the air

Monitoring air quality is important as poor air quality can lead to negative health effects such as tiredness, headaches, loss of concentration, and increased heart rate. One of the most harmful forms of air pollution is particulate matter, which can penetrate deep into the lungs, bloodstream, and brain, causing various health problems.

To measure PM2.5 or particulate matter in the air, you can use an Arduino board in combination with a PM2.5 sensor such as the PMS5003. This sensor can detect the number and concentration of particles in the air, specifically those with a diameter of around 2.5 microns, which are referred to as PM2.5. The PMS5003 is a low-cost, digital and universal particle concentration sensor that can be easily interfaced with an Arduino board. It works on the principle of laser scattering, where a fan creates a controlled airflow so that environmental particulates pass through a focused laser beam. The particulates cause light scattering, which is detected by a photodiode and then converted into PM concentration with the help of a microprocessor.

When setting up the Arduino board, ensure you have the correct pins and layout, as they can vary. The PM2.5 sensor communicates with the Arduino through a serial interface, and you will need a voltage divider as the RX logic level works at 3.3V. Connect PIN1 VCC of the PMS5003 to Arduino 5V Pin and PIN2 GND to GND of Arduino. The UART Pin, PIN4 Rx, and PIN5 Tx should be connected to Arduino pins 3 and 4 respectively. The sensor outputs serial data at 9600 baud, which can be read by many computers, and the device can be powered via a Mini USB connector.

In addition to the PMS5003, other sensors can also measure PM2.5, such as the MH-Z19, which can also output PM1 and PM10 values. This sensor uses the non-dispersive infrared principle to measure the concentration of CO2 in the air. An infrared source directs light through a tube filled with the air being measured, and an optical filter and an IR detector measure the amount of IR light that passes through, with CO2 gas molecules absorbing a specific band of light.

By following these steps and using the appropriate sensors, you can effectively measure PM2.5 or particulate matter in the air using an Arduino board, contributing to a better understanding of air quality and its impact on health.

Measuring CO2 or carbon dioxide in the air

Arduino is a versatile tool with a wide range of applications, including the measurement of CO2 or carbon dioxide in the air. This is particularly useful in monitoring air quality, which can have a significant impact on health and well-being.

One of the most commonly used sensors for measuring CO2 with Arduino is the MQ-135 sensor. This sensor can accurately detect CO2 levels in the atmosphere and display the data on an OLED module. To use this sensor, you need to download the MQ135 library and preheat the sensor for 24 hours before reading the Ro values. After preheating, you can use the provided code to read the Ro values and make the necessary adjustments.

Another option for measuring CO2 is the Atlas Scientific sensor, which can be hooked up to an Arduino Uno. This setup provides real-time readings in PPM (parts per million) on a liquid crystal display (LCD). Both the sensor and the display are connected to the Arduino via I2C.

In addition to these sensors, there are also low-cost, pocket-sized setups based on Arduinos that are economic and customizable. These setups typically include an Arduino board, a CO2 sensor, an SD card module, and a control panel.

It is important to note that before testing the sensor, you should connect the Arduino to a laptop, select the board and port, and upload the code. Then, open the serial monitor to view the final data.

By utilizing these methods and tools, you can effectively measure CO2 or carbon dioxide levels in the air using Arduino, contributing to a better understanding of air quality and its potential effects.

Understanding the Air Quality Index (AQI)

The Air Quality Index (AQI) is a tool developed by the U.S. Environmental Protection Agency (EPA) to communicate information about outdoor air quality and health to the public. The AQI is designed to be a simple and uniform way to report daily air quality conditions and is calculated by converting measured pollutant concentrations to a uniform index based on the health effects associated with a pollutant.

The EPA establishes an AQI for five major air pollutants regulated by the Clean Air Act: particle pollution, ground-level ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Each of these pollutants has a national air quality standard set by the EPA to protect public health, and the AQI value represents the level of air pollution and the associated health concerns. The higher the AQI value, the greater the level of air pollution and the more significant the health concerns.

The AQI includes six color-coded categories, each corresponding to a range of index values. For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 indicates hazardous air quality. AQI values at or below 100 are generally considered satisfactory, while values above 100 indicate unhealthy air quality for certain sensitive groups, and the health risks increase as the AQI values climb higher.

The AQI is an essential tool for monitoring air quality and protecting public health. It helps residents avoid risks associated with air pollution and enables authorities to take necessary actions to improve air quality and safeguard the well-being of the community.

Building an IoT-based air pollution monitoring system

Air pollution is a serious issue, causing over 4 million deaths per year. With microcontrollers like Arduino, it is now possible to build your own low-cost air quality monitoring systems. This article will guide you through the process of building an IoT-based air pollution monitoring system using an Arduino.

Components

The core of this project is the Arduino board, which processes data from various sensors to provide information about air quality. The specific Arduino model used in this project is the Arduino UNO board, a popular and simple option for beginners. The MQ135 gas sensor is connected to the Arduino's analog pin, allowing it to detect various gases and provide data on air quality. Additionally, a DHT11 sensor is included to measure humidity and temperature. These sensors are readily available and affordable, making this project accessible to enthusiasts.

Setup

The OLED screen, DHT11, and MQ135 gas sensor are all connected to the Arduino Uno on a breadboard. The Arduino is linked to the OLED screen using the I2C protocol, facilitated by the SDA and SCL pins. The DHT11 sensor is connected to the Arduino's digital pin, and the MQ135 sensor is connected to the analog pin. The Arduino code, provided in the sources, should be uploaded to the board.

Functionality

The system operates by utilizing sensors to detect environmental parameters such as gas levels, temperature, and humidity. Analog readings from the MQ135 gas sensor are mapped to predefined thresholds, categorizing air quality as "Good," "Poor," "Very Bad," or "Toxic." The DHT11 sensor measures humidity and temperature, providing additional context to the gas sensor data. By continuously monitoring these parameters, the system offers real-time insights into air quality, enabling users to respond to changes in their environment.

Applications

This IoT-based air pollution monitoring system can be used to assess indoor or outdoor air quality. For indoor use, it can help monitor air pollution from cooking, smoking, or burning candles. When used outdoors, it can provide data on pollution from combustion engines, helping to raise awareness about the invisible dangers in the air we breathe.

Frequently asked questions