# Air Quality and AQI Info **URL:** https://forum.airnowtech.org/c/aqi/24.md [Latest](https://forum.airnowtech.org/latest.md) · [Categories](https://forum.airnowtech.org/categories.md) · [Tags](https://forum.airnowtech.org/tags.md) --- ## [About the Air Quality and AQI Info category](https://forum.airnowtech.org/t/about-the-aqi-info-category/167)
**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\ **Replies:** 0\ **Last updated:** [June 30, 2016, 4:19pm UTC](https://forum.airnowtech.org/t/about-the-aqi-info-category/167 "2016-06-30T16:19:34Z")
Ask questions or find answers regarding the Air Quality Index (AQI) for ozone, PM2.5, and PM10, including the NowCast and Daily AQI calculations. --- ## [The NowCast for PM2.5 and PM10](https://forum.airnowtech.org/t/the-nowcast-for-pm2-5-and-pm10/172)
**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")
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… --- ## [The AQI Equation](https://forum.airnowtech.org/t/the-aqi-equation/169)
**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\ **Replies:** 0\ **Last updated:** [July 5, 2016, 10:37pm UTC](https://forum.airnowtech.org/t/the-aqi-equation/169 "2016-07-05T22:37:44Z")
AQI Equation Where Conci = Input concentration for a given pollutant ConcLo = The concentration breakpoint that is less than or equal to Conci ConcHi = The concentration breakpoint that is greater than or equal to C… --- ## [The Nowcast for Ozone - 2019 Update (Partial Least Squares Method)](https://forum.airnowtech.org/t/the-nowcast-for-ozone-2019-update-partial-least-squares-method/356)
**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\ **Replies:** 0\ **Last updated:** [July 26, 2019, 1:54pm UTC](https://forum.airnowtech.org/t/the-nowcast-for-ozone-2019-update-partial-least-squares-method/356 "2019-07-26T13:54:08Z")
On August 1, 2019, the AirNow Data Management Center implemented a new EPA method for calculating the ozone Nowcast using a Partial Least Squares (PLS) method. All relevant R code and corresponding white paper cited in t… --- ## [Daily and Hourly AQI - PM10](https://forum.airnowtech.org/t/daily-and-hourly-aqi-pm10/263)
**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\ **Replies:** 0\ **Last updated:** [April 10, 2018, 9:22pm UTC](https://forum.airnowtech.org/t/daily-and-hourly-aqi-pm10/263 "2018-04-10T21:22:14Z")
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… --- ## [Daily and Hourly AQI - Ozone](https://forum.airnowtech.org/t/daily-and-hourly-aqi-ozone/170)
**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\ **Replies:** 0\ **Last updated:** [July 5, 2016, 10:48pm UTC](https://forum.airnowtech.org/t/daily-and-hourly-aqi-ozone/170 "2016-07-05T22:48:18Z")
Daily Ozone AQI The daily ozone AQI is calculated by taking the maximum 8 hour concentration from 07:00-23:00 LST, and then converting to AQI. Each 8-hour average concentration is truncated to .001ppm/1ppb. There are 17 … --- ## [Daily and Hourly AQI - PM2.5](https://forum.airnowtech.org/t/daily-and-hourly-aqi-pm2-5/171)
**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")
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… --- ## [The AQI Equation (2024 - Valid Beginning May 6th, 2024)](https://forum.airnowtech.org/t/the-aqi-equation-2024-valid-beginning-may-6th-2024/453)
**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\ **Replies:** 0\ **Last updated:** [March 18, 2024, 12:24pm UTC](https://forum.airnowtech.org/t/the-aqi-equation-2024-valid-beginning-may-6th-2024/453 "2024-03-18T12:24:27Z")
AQI Equation Where Conci = Input concentration for a given pollutant ConcLo = The concentration breakpoint that is less than or equal to Conci ConcHi = The concentration breakpoint that is greater than or equal to C… --- ## [Forecasting Ozone and PM concentrations from AQI values](https://forum.airnowtech.org/t/forecasting-ozone-and-pm-concentrations-from-aqi-values/439)
**Author:** [@rvr5005](https://forum.airnowtech.org/u/rvr5005)\ **Replies:** 1\ **Last updated:** [April 18, 2023, 1:26pm UTC](https://forum.airnowtech.org/t/forecasting-ozone-and-pm-concentrations-from-aqi-values/439 "2023-04-18T13:26:46Z")
I use an in-house AQ model using regression statistics (that I did not develop myself) and need to better understand the formulas used. If anyone has any input on the formula pasted below I would greatly appreciate it. … --- ## [Daily and Hourly AQI – Other Pollutants](https://forum.airnowtech.org/t/daily-and-hourly-aqi-other-pollutants/432)
**Author:** [@atutterow](https://forum.airnowtech.org/u/atutterow)\ **Replies:** 0\ **Last updated:** [November 16, 2022, 3:26pm UTC](https://forum.airnowtech.org/t/daily-and-hourly-aqi-other-pollutants/432 "2022-11-16T15:26:10Z")
Daily AQI SO2 Daily SO2 concentrations are based on the 24-hr average. 75%, or 18/24 hours of data are needed for a valid daily concentration. Please note that AirNow does not currently report daily AQI for SO2. If neede… --- ## [The NowCast for Ozone (obsolete as of 08/01/2019)](https://forum.airnowtech.org/t/the-nowcast-for-ozone-obsolete-as-of-08-01-2019/264)
**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\ **Replies:** 0\ **Last updated:** [April 10, 2018, 10:13pm UTC](https://forum.airnowtech.org/t/the-nowcast-for-ozone-obsolete-as-of-08-01-2019/264 "2018-04-10T22:13:27Z")
IMPORTANT: As of 08/01/2019 This is no longer the NowCast method used for ozone. See information on the new method here Nowcast Overview From the EPA’s AQI Technical Assistance Document page 7: EPA uses the NowCast to… --- ## [AQI Calculations Overview- Ozone, PM2.5 and PM10](https://forum.airnowtech.org/t/aqi-calculations-overview-ozone-pm2-5-and-pm10/168)
**Author:** [@mwhylton](https://forum.airnowtech.org/u/mwhylton)\ **Replies:** 0\ **Last updated:** [July 5, 2016, 10:30pm UTC](https://forum.airnowtech.org/t/aqi-calculations-overview-ozone-pm2-5-and-pm10/168 "2016-07-05T22:30:24Z")
Overview The AQI was developed by the EPA and is used to convey how clean or polluted the air around you is. There are 6 separate AQI levels: Good, Moderate, Unhealthy for Sensitive Groups (USG), Unhealthy, Very Unhealth…