# PM2.5

**URL:** https://forum.airnowtech.org/c/aqi/pm2-5/31.md

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## [About the PM2.5 category](https://forum.airnowtech.org/t/about-the-pm2-5-category/259)

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**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\
**Replies:** 0

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## [The NowCast for PM2.5 and PM10](https://forum.airnowtech.org/t/the-nowcast-for-pm2-5-and-pm10/172)

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**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\
**Replies:** 0\
**Last updated:** [July 15, 2016, 9:28pm UTC](https://forum.airnowtech.org/t/the-nowcast-for-pm2-5-and-pm10/172 "2016-07-15T21:28:57Z")

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Nowcast Overview From the EPA’s AQI Technical Assistance Document page 7: EPA uses the NowCast to approximate the complete daily AQI during any given hour. Even on days when the AQI forecast predicts unhealthy conditi…

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## [Daily and Hourly AQI - PM2.5](https://forum.airnowtech.org/t/daily-and-hourly-aqi-pm2-5/171)

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**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\
**Replies:** 0\
**Last updated:** [July 5, 2016, 10:56pm UTC](https://forum.airnowtech.org/t/daily-and-hourly-aqi-pm2-5/171 "2016-07-05T22:56:37Z")

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Daily PM2.5 AQI The daily PM2.5 AQI is calculated by taking the 24-hour concentration average from midnight to midnight (Local Standard Time) and converting to AQI using the PM2.5 cutpoints. 75%, or 18/24 hours of data a…