By Alisha Ebrahimji and Holly Yan, CNN
The fiery derailment in early February prompted fears of a catastrophic explosion of vinyl chloride -- a highly flammable chemical linked to an increased risk of cancer. After a mandatory evacuation order, crews released vinyl chloride into a trench and burned it off -- averting an explosion but spawning new health concerns.
Officials have said tests show the air and municipal water are safe and allowed residents to return home. But some have reported a variety of new health problems including rashes, nausea, bloody noses and trouble breathing.
CNN is chronicling the latest events as new information unfolds. Here's what we know:
Correction: An earlier version of this story misspelled the first name of Ohio Environmental Protection Agency official Tiffani Kavalec.
™ & © 2023 Cable News Network, Inc., a Warner Bros. Discovery Company. All rights reserved.