© Ranta Images/GettyReports are spreading of a mysterious vaping-related lung disease
Two deaths in the US have now been attributed to vaping-related lung conditions, and state governments are taking actions to crack down on the types of e-cigarettes available. Here's what you need to know about this mysterious illness and the response to the outbreak.

How did these deaths occur?

In July, an Illinois resident developed a lung infection and died after using a vaping device that contained marijuana oil. Yesterday, officials in Oregon said that a resident of the state who used e-cigarettes had also died after being hospitalised for a severe lung infection. It's not clear why these respiratory problems led to the people's deaths. It could be that something either in the e-cigarette or the substances smoked through them caused serious inflammation of the lungs.

Has anyone else got ill from vaping?

The US Centers for Disease Control and Prevention (CDC) says that as of 27 August, 215 possible cases of vaping-related severe lung disease have been reported by 25 states. In addition to the deaths in Illinois and Oregon, this multistate outbreak includes people who have reported coughs, shortness of breath, chest pain, fever, fatigue, nausea, vomiting and diarrhoea. These symptoms developed over days or weeks. Some people turn up to hospital with symptoms that look like pneumonia, and have been put on ventilators or treated in intensive care units.

Do we know whether these symptoms are caused by vaping?

We're not certain, but there could be a connection. In every one of these cases, people reported using e-cigarettes. But no single e-cigarette product or substance has been associated with all the illnesses. The CDC says that recent inhalation of cannabis products and THC, the main psychoactive compound in marijuana, has been reported in many patients from two states.

Ann Thomas, a public health physician in Oregon, said in a statement that we don't yet know the exact cause of these illnesses, or whether they're due to contaminants, to ingredients in the liquid used in e-cigarettes, or to the devices themselves.

One potential cause has been identified by the US Food and Drug Administration (FDA), according to reports in the Washington Post. An oil derived from vitamin E was found in nearly all cannabis samples from people who fell ill in New York. But that oil wasn't found in tests of the nicotine products that had been used by others who also had lung problems after vaping.

So, are e-cigarettes dangerous?

We simply don't know. Some research has shown that vaping is less harmful than smoking traditional cigarettes, but using e-cigarettes still carries a risk. "Vaping exposes users to many different substances for which we have little information about related harms - including flavourings, nicotine, cannabinoids, and solvents," said CDC Director Robert Redfield in a statement.

The CDC also issued a warning to the public not to buy e-cigarette products off the street, and not to modify the devices.

What is happening now?

Public health departments in some states are urging people to stop using any kind of vaping device immediately. On 4 September, Michigan became the first US state to ban flavoured e-cigarettes. The state's governor ordered the Michigan Department of Health and Human Services to ban the sale of flavoured nicotine vaping products in stores and online, as well as ban the marketing of vaping products as clean, safe or healthy.

These flavoured options are marketed heavily to young people, who are increasingly using e-cigarettes. The FDA found in 2018 that vaping increased 78 per cent from 2017 to 2018 among high school students, and 48 per cent among middle school students.

UPDATE: The state of Indiana confirmed on Friday that a third person over the age of 18 had died from a severe lung injury linked to a history of vaping. The state says it is investigating a total of 30 cases of lung disease linked to vaping.