Asthma sufferers have revealed the plight of the disease in a moving documentary, including one who is at risk of a full-blown attack anytime she gets on a bus.
Frida Batsby says she takes a risk every time she gets on the bus to university, with smoke, dust and even perfume setting her asthma off.
Fellow patient Amanda Collin likens an asthma attack to being trapped 'underwater, gasping for breath'.
While Jean Falkiner, whose symptoms went undiagnosed for years, compares the ordeal to having an 'anvil stuck on your chest that you cannot get off'.
The documentary BREATHLESS: The Story Of Life With Severe Asthma was created by filmmaker Michelle Coomber.
One in 12 adults in the UK are being treated for the common condition, Asthma UK statistics show.
And in the US, one in 13 people suffer, according to the Centers for Disease Control and Prevention.
Severe asthma is a specific type of the condition that does not get better with go-to medication. It affects around 200,000 people in the UK.
Some people's airways may be too inflamed for normal drugs to have an effect or the inflammation could be brought on by chemicals that are not targeted by go-to treatments.
'Imagine you're underwater trying to gasp for air'
Ms Collins was diagnosed with asthma when she was just 18 months old, with it being 'all she has known'.
Having spent much of her childhood in and out of hospital, she remembers a friend she made on the ward having a cardiac arrest minutes after she started coughing.
Speaking of an asthma attack, Ms Collins said: 'Imagine if you're underwater and you're trying with every effort you can to gasp for breath.
'And that desperation as if you're trying to come up for air.'
Amanda Collins (pictured) describes an asthma attack as feeling like you are 'trapped under water, gasping for air'. Her symptoms sometimes leave her unable to walk down the stairs
Ms Collins, 40, claims her symptoms can become so severe she is unable to get down the stairs or feed herself.
She credits oral steroids for 'saving her life many times' but is forced to tolerate the side effects, including bloating, insomnia and mood swings.
Oral steroids help to calm the airways and stop inflammation by blocking the effects of chemicals released by the immune system.
If taken long term, they have been linked to a greater risk of infection, high blood pressure and weak bones.
Ms Collins, who lives in England, has developed osteoporosis as a result of the drugs, with her bone density reportedly being that of a person twice her age.
'There's no going back from osteoporosis,' she said.
Ms Collins feels she has 'slipped through the net', having