People suffering from asthma are dying unnecessarily because of complacency among both medical staff and patients, according to the first national study of asthma deaths in the UK.
Researchers found that in nearly half of the cases they looked at, asthma sufferers did not receive any medical help during their final asthma attack.
The National Review of Asthma Deaths says sufferers and medics must be better at recognising the danger signs.
The UK has 5.5 million asthmatics.
Although deaths linked to the condition have been falling, there were 1,242 in 2012 - meaning the UK has some of the highest asthma death rates in Europe.
Holly Sparshott, from Gosport, died of asthma at the age of 12. Her mother, Sarah, is campaigning to raise awareness about how dangerous the disease can be.
The national study involved a detailed examination of the circumstances around 195 such deaths.
Among the review's key findings were:
- The standard of care received was less than satisfactory in a quarter of cases where people died and there was "room for improvement" in the care received by 83% of those who died.
- Triggers for asthma attacks had not been documented in more than half of the cases and 57% were not recorded as being under specialist supervision in the year before death.
- Deficiencies were found in both routine care and in the treatment of attacks.
- There was widespread under-use of preventer inhalers and excessive over-reliance on reliever inhalers.
- 10% of those who died did so within one month of discharge from hospital following treatment for asthma; at least 21% had attended an emergency department at least once in the previous year.
- Over half of those who died were being treated for mild or moderate asthma at the time; experts concluded that this was mostly because neither doctors nor patients themselves recognised how serious their asthma really was.
- Of those who died, 19% were smokers and others, including many children, were exposed to second-hand smoke in the home.
- Some patients had not collected their prescriptions for preventative treatment or did not attend regular asthma check-ups.
Researchers found that clinicians and patients alike had become complacent about the illness.
Since asthma symptoms can come and go, some patients may forget or feel they don't need to keep taking their medication, for example.
The report calls for better monitoring and improved education for doctors, nurses, patients and carers.
Dr Kevin Stewart of the Royal College of Physicians, which managed the review, said: "It's time to end our complacency about asthma, which can, and does, kill. There are important messages in this report for clinicians, for patients and their families and for policy-makers.
"We haven't paid enough attention to the importance of good routine asthma care by clinicians with the right training and experience and the part that patients themselves play in this.
"Too often we have also been slow to detect signs of poor asthma control and slow to act when these have been present, with tragic consequences for some families."
Prof Chris Griffiths of Queen Mary University of London was also involved in the report.
He said it revealed that care had deteriorated since an analysis in 2005.
Prof Griffiths said: "These worrying statistics can and must be turned around in the next decade.
"Those of us who work in general practice must implement the recommendation to have a named clinician responsible for asthma in each practice.
"Despite facing huge challenges as we work to meet current NHS organisational change, we need to prioritise asthma care in order to reduce deaths in the UK."
Kay Boycott, chief executive of the Asthma UK says the charity "wholeheartedly endorses" the report.
She said: "This confidential enquiry has identified prescribing errors of a frankly horrifying scale and is a damning indictment of current routine practice."
In many of the cases the experts examined, warning signs were found to have been ignored.
'Call to action'
Ms Boycott added: "Past attacks are a clear risk factor for future attacks, but more than two-thirds of the people hospitalised in the month before they died did not get properly checked up afterwards.
"It's heart-breaking that the review has found 46% of deaths could have been avoided with better routine care."
Prof Mike Morgan, NHS England's national clinical director for respiratory services, said: "These statistics are a call to action for commissioners, health professionals and patients.
"Every patient should have a care plan which should be regularly reviewed and patients should be supported to manage their asthma, including effective inhaler technique and knowledge of their condition."
The Irish, Scottish and Welsh Governments said they would look closely at the key findings of the report.
A spokesman for the Department of Health in Northern Ireland (DHSSPS) said: "As part of its continuing commitment to improve services, the department will consider the findings and recommendations of the National Review of Asthma Deaths and what lessons can be learned from the report."