I live in California and may have been exposed to carbon monoxide. What is the first thing I should do?

First, treat a possible carbon-monoxide (CO) exposure or alarm as an emergency: get everyone, including pets, into fresh air, call 911 or the fire department, and do not re-enter or try to locate the source until responders say it is safe. Seek prompt medical evaluation for anyone exposed or feeling unwell, and tell the clinician about the possible CO exposure. CO is odorless and colorless; reported symptoms can include headache, dizziness, weakness, nausea, chest pain, or confusion. Serious exposure can affect the brain or heart, and CDC advises discharged patients about possible delayed neurologic complications and follow-up. After safety and care, preserve information: photographs, alarm information, lease or maintenance requests, repair invoices, witness names, and medical records. Avoid altering a suspected appliance or alarm before it is inspected. California generally requires dwelling owners to install approved CO devices in homes with a fossil-fuel appliance, fireplace, or attached garage. A legal claim still turns on evidence of a responsible party’s duty, breach, causation, and damages. Injury claims are generally subject to a two-year filing period; claims against a public entity usually require an administrative claim within six months.