{"id":2054,"date":"2019-04-13T13:00:14","date_gmt":"2019-04-13T12:00:14","guid":{"rendered":"https:\/\/chewett.co.uk\/blog\/?p=2054"},"modified":"2019-04-14T23:56:40","modified_gmt":"2019-04-14T22:56:40","slug":"mq-135-air-quality-and-hazardous-gas-sensor-for-arduino-review-and-code","status":"publish","type":"post","link":"https:\/\/chewett.co.uk\/blog\/2054\/mq-135-air-quality-and-hazardous-gas-sensor-for-arduino-review-and-code\/","title":{"rendered":"MQ-135 Air Quality and Hazardous Gas Sensor For Arduino Review and Code"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

This post talks about using the MQ-135 Air Quality and Hazardous Gas sensor with an Arduino. <\/p>\n\n\n\n\n\n\n\n

MQ-135 Air Quality and Hazardous Gas Sensor<\/h2>\n\n\n\n
\"\"<\/figure><\/div>\n\n\n\n

The MQ-135 air quality and hazadous gas sensor is a small unit that reports the relative quality of the air.<\/p>\n\n\n\n

This specific variant works particularly well with detecting carbon dioxide,
benzene, alcohol, and smoke in the air.<\/p>\n\n\n\n

These gasses are typically used as a measure of air quality. This is why this sensor is typically sold as a “Air quality and hazardous gas sensor”.<\/p>\n\n\n\n

The analogue pin will output a relative value according to the amount of particulates in the air.<\/p>\n\n\n\n

Without calibration it is not possible to relate this to a specific concentration (in parts per million) but works well as a relative measure.<\/p>\n\n\n\n

When using this in an area you will be able to detect if the air quality is getting better or worse by the trend in values reported.<\/p>\n\n\n\n

Wiring it up to an Arduino<\/h2>\n\n\n\n

This MQ-135 sensor has two pins which can be used to read the value of the sensor. The first is a basic analogue pin which will return a value between 0 and 5 volts.<\/p>\n\n\n\n

This voltage represents a relative range of high to low gas concentration. The lower the voltage the lower the amount of gas detected.<\/p>\n\n\n\n

On the underside of the sensor a potentiometer allows configuring of the digital pin. The digital pin will be brought high once a specific level of gas is detected. This level is set by the potentiometer on the back.<\/p>\n\n\n\n

\"\"

<\/figcaption><\/figure>\n\n\n\n

The VCC pin must be connected to the 5 volt pin on the Arduino. The GND pin must similarly be connected to the Ground pin on the Arduino.<\/p>\n\n\n\n

Programming the Arduino with the
MQ-135 Air Quality and Hazardous Gas Sensor <\/h2>\n\n\n\n

In this post I am using the analogue pin to read the relatively value of the sensor.<\/p>\n\n\n

\n#define ANALOG_IN_PIN 0\nint sensorVal = 0;\n\nvoid setup() {\n  Serial.begin(115200);\n}\n\nvoid loop() {\n  sensorVal = analogRead(ANALOG_IN_PIN);\n  Serial.println(sensorVal);\n  delay(2000);\n}\n<\/pre><\/div>\n\n\n
Here the serial out is  initialized in the setup. In the loop method the sensor is continually read from ANALOG_IN_PIN<\/code>, and sent on the serial line.<\/p>\n\n\n\n
Final Review<\/h2>\n\n\n\n
This is a simple air quality sensor which can be used to calculate the quality of the air. It is typically used to compare the relatively air quality in an area over time.<\/p>\n\n\n\n
With some work it can be calibrated to give a more specific value in parts per million but this was not done here.<\/p>\n\n\n\n
Providing both an analogue and digital pin to read the output gives various options to its use. This is especially useful in smaller IoT projects where pins are at a premium.<\/p>\n\n\n\n
Since this is a small and useful sensor I would definitely look at using this in a project again.<\/p>\n\n\n\n
Would buy again!<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"
This post talks about using the MQ-135 Air Quality and Hazardous Gas sensor with an Arduino.<\/p>\n","protected":false},"author":1,"featured_media":2058,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"Today I talk about the #MQ135 Air Quality and Hazardous Gas #Sensor For #Arduino #Review and #Code","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[97],"tags":[132,131,333,343,152],"class_list":["post-2054","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-electronics","tag-arduino","tag-arduino-sensor","tag-gas-sensor","tag-mq-135","tag-sensor"],"wppr_data":{"cwp_meta_box_check":"No"},"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/chewett.co.uk\/blog\/wp-content\/uploads\/2019\/03\/MQ-135-Sensor-Air-Quality-Sensor-Hazardous-Gas-Detection-Module-for-Arduino_posticon.jpg?fit=800%2C800&ssl=1","jetpack_shortlink":"https:\/\/wp.me\/p2toWX-x8","jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":745,"url":"https:\/\/chewett.co.uk\/blog\/745\/ds18b20-onewire-temperature-sensor\/","url_meta":{"origin":2054,"position":0},"title":"DS18B20 onewire temperature sensor","author":"Chewett","date":"November 15, 2017","format":false,"excerpt":"The DS18B20 temperature sensor is a digital temperature sensor using the 1-Wire protocol. 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