PHMSA has updated the Emergency Response Guidebook (ERG) to the 2020 version. You can see the changes and updates from the 2016 version of the ERG here. You can also download the ERG app if needed to your iPhone from the Apple App Store.

Below is a link to the PHMSA ERG website, it includes some general information on the use of the ERG and also a link to a video on how to use it.

https://www.phmsa.dot.gov/hazmat/erg/emergency-response-guidebook-erg