Why Temtop and AirNow tell you different AQI scores?

When you look at the AQI or PM2.5 readings from Temtop and other sources such as AirNow or PurpleAir, you may wonder why the readings are incompatible. To understand the air quality around you, it is essential to acknowledge how these air quality sources work and what their accuracy is based on. There are a few things you should consider when comparing the air quality readings from different sources. As shown in the table below, the data source, time interval and calculation are key points to determine the air quality accuracy.



Temtop measurements are based on the actual location of the device. Additionally, when indoors, the unit is prone to show distinct readings as you change the environments, even small actions such as opening and closing the windows can affect the readings.

In terms of accuracy, Temtop readings are mostly based on the current time and position of the device while PurpleAir uses nearby sensors for correction.

AQI has shown to be a topic of big concern among the population. However, many people are unaware that AQI index is based on certain national standards. Also, it is quite common for local air quality measurement sites follow to different or have their standards.

For instance, AirNow’s AQI readings use ozone, PM10, and PM2.5, even NO2 and CO in some locations. While, PurpleAir provides AQI readings from various conversion methods including US EPA PM2.5, US EPA PM10, Australian PM2.5 AQI and etc... Temtop’s AQI is given directly through the device display rather than online data website, therefore Temtop’s AQI is converted from current PM2.5 or PM10 reading using US EPA standards.

Occasionally you may find discrepancies between the PM2.5 and AQI. By using the AirNow AQI calculator, you can perform a simple analysis, when the PM2.5 is 8 and 10ug/m3, AQI is 33 and 42 respectively. But even tiny differences on the PM2.5 can cause huge impact on the AQI readings. For example, when the PM2.5 differs only by 2 readings, the AQI differs by 9. Thus, before assuming that your AQI readings is surprisingly large, it is ideal to first check and analyze the accuracy of the PM2.5 sensor.

In the current modern society, there has been a growth on construction sites activities, rapid industrialization and rise on the private transportation, these and many other factors contribute to high levels of air pollution. Although, public awareness regarding the impact of pollutants on human health also rises accordingly. The lack of knowledge about air quality measurements sources is quite evident, understanding the healthy and unhealthy levels of air quality is just the start to breathe better air.