# Daily and Hourly AQI - PM10

**URL:** https://forum.airnowtech.org/t/daily-and-hourly-aqi-pm10/263
**Category:** PM10
**Created:** [April 10, 2018, 9:22pm UTC](https://forum.airnowtech.org/t/daily-and-hourly-aqi-pm10/263 "2018-04-10T21:22:13Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![mwhylton](https://forum.airnowtech.org/user_avatar/forum.airnowtech.org/mwhylton/32/21_2.png) [@mwhylton](https://forum.airnowtech.org/u/mwhylton)
#### Post date: [April 10, 2018, 9:22pm UTC](https://forum.airnowtech.org/t/daily-and-hourly-aqi-pm10/263/1 "2018-04-10T21:22:14Z")

</div>

## Daily PM10 AQI

The daily PM10 AQI is calculated by taking the 24-hour concentration average from midnight to midnight (Local Standard Time) and converting to AQI using the PM10 cutpoints. 75%, or 18/24 hours of data are needed for a valid daily AQI calculation.

Example 1: Valid with Missing Data

 ![](https://forum.airnowtech.org/uploads/default/original/1X/1fecd9cd4c1587299b0b77dac321d26b55211af3.PNG)

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## Hourly PM10 AQI

### NowCast AQI method

For real-time and other hourly readings, the NowCast method is used to calculate the AQI for each hour. In 2021, the NowCast also replaced the midpoint averaging method (described below) for hourly AQI from older hours. For information on how to calculate the NowCast for PM10, click [here](https://forum.airnowtech.org/t/the-nowcast-for-ozone-pm2-5-and-pm10/172).