The Plantower PMS5003 sensor can detect particles as small as 0.3 micrometres. This is why the model number of the sensor ends with ‘003’. The 5 refers to the series generation.   The most common type of air quality sensor that measures PM2.5 uses a laser to detect particulate matter. There are two types of these laser-based sensors: ones without a fan like the Samyoung DSM501A and ones which have a fan like the Plantower PMS5003. The fanless versions are cheaper but are also less accurate. The Plantower PMS5003 that we will use is the best DIY model that is still quite affordable.