Can thermal imaging cameras help spot coronaviruses?


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A thermal imaging camera used in a train station in Bilbao, May 2020

As the locks are released, thermal cameras are popping up in all kinds of public places to assess people’s health.

What do thermal imaging cameras do?

Using infrared technology, thermal imaging cameras detect radiant heat from a body – usually the forehead – and then estimate the body’s core temperature. These cameras are an extremely powerful tool, often deployed by firefighters to track hot embers and police to search for suspects out of sight.

But they are not intended to be medical devices. How useful are they in the current pandemic?

They can give a reasonable measure of skin temperature, to the nearest half a degree – but it’s not the same as body temperature.

“These devices, in general, are less accurate than thermometers for medical devices like the ones you stick in the ear,” said Derek Hill, professor of medical imaging science at University College London.

What is normal body temperature?

About 37C (98.6F). A high temperature is generally considered to be 38 ° C or more. But the normal temperature can vary from person to person and change throughout the day. It can also fluctuate during a woman’s monthly cycle.

Taking an accurate measurement of central body temperature is not easy. Although it can be measured on the forehead, mouth, ear and armpits, the most accurate way is to do a rectal reading.

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Body temperature

  • 37 ° C(98.6 ° F) normal body temperature

  • 38 ° C(100.4 ° F) or higher, high temperature / fever

Source: NHS

Do thermal cameras detect coronaviruses?

No, they only measure temperature. High temperature or fever is just a common symptom of the virus. Others include nausea, headache, fatigue, and loss of taste or odor. But not everyone with the virus has a high temperature and not everyone with a high temperature is infected with the coronavirus.

Thus, thermal imaging cameras alone will miss infected people with other symptoms or no symptoms at all – known as false negatives. They will also identify people with fever for another reason – known as false positives.

So are thermal imaging cameras useful?

Temperature control alone “may not be very effective,” says the World Health Organization. The cameras must be correctly configured and take into account the ambient temperature. One risk is that the cameras could put operators to sleep in a false sense of security.

“They’re … just one of many tools,” said James Ferryman, professor of computer vision at the University of Reading.

What if I wear a face mask or a tarp?

“The heat that radiates from the skin is likely to be affected by wearing face masks,” says Professor Ferryman.

This is why most temperature measurements are based on the forehead, which is usually exposed.

Will I be warmer if I exercise?

Not necessarily. The temperature of the skin actually decreases during exercise because perspiration appears on the surface of the skin.

The body is good enough to regulate its temperature even after exercise, so it should be really high enough to appear.

How else do I take my temperature?

With portable thermometers pointed at the forehead. They do not need to touch the skin, but should be a few inches from it. Although accurate to a fraction of a degree near skin temperature, they correctly detect fever about 90% of the time compared to a rectal thermometer, says Professor Hill.

Where can I expect to be temperature tested?

Thermal scanners are now in place at some UK airports – including Bournemouth. The temperature control is being tested for some passengers at Heathrow, while Manchester Airport says the equipment is also being tested – but the results will not be communicated to passengers or “used to influence whether a customer can travel”. The international ferry port of Portsmouth has also installed a thermal scanner to filter departing passengers.

  • Coronavirus: what are the UK travel quarantine rules?

Schools are deploying portable laser thermometers to check children every morning. And some employers are planning to introduce staff testing in the workplace.

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Digital thermometers are used in schools to check children

At work, do I have to take a temperature test?

Under UK employment law, individuals must agree before an employer can monitor the temperature of staff members. Certain employment contracts will already allow this type of test to be carried out, by what is called “implied consent”.

If employees don’t agree – and there is no pre-agreed policy covering the situation – then taking the temperature of someone is illegal, says the professional organization for HR and people development. Employers must also treat medical information they collect fairly and transparently – according to the Information Commissioner.

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CoronaVirus translator

What do all these terms mean?

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  • Antibody test
    A medical test that can show if a person has had coronavirus and now has some immunity. The test detects antibodies in the blood, which are produced by the body to fight the disease.
  • Asymptomatic
    Someone who has an illness but has none of the symptoms it causes. Some studies suggest that some people with coronavirus are carriers of the disease, but do not have common symptoms, such as a persistent cough or high temperature.
  • Containment phase
    The first part of the UK’s strategy to fight the coronavirus, which involved quickly identifying infected people and tracking down anyone who had been in close contact with them.
  • Coronavirus
    One of a group of viruses that can cause serious or mild illness in humans and animals. The coronavirus that is currently sweeping the world is the cause of Covid-19 disease. Colds and flu (flu) are other types of coronaviruses.
  • Covid-19
    The coronavirus disease first detected in Wuhan, China in late 2019. It mainly affects the lungs.
  • Delay phase
    The second part of the UK’s strategy to combat the coronavirus, in which measures such as social isolation are used to delay its spread.
  • Fixed penalty notice
    A fine designed to deal with an offense on the spot, rather than in court. These often relate to driving offenses, but now also cover anti-social behavior and violations of coronavirus locking.
  • Flatten the curve
    Health experts use a line on a graph to display the number of new cases of coronavirus. If many people get the virus in a short period of time, the line may suddenly increase and look a bit like a mountain. However, taking steps to reduce infections can spread the cases over a longer period of time and means the “curve” is flatter. This makes it easier for health systems.
  • Influenza
    Abbreviation for influenza, a virus that regularly causes illness in humans and animals during seasonal epidemics.
  • Leave
    Supports companies affected by the coronavirus by temporarily helping to pay the salaries of certain employees. It allows employees to stay on the payroll even when they are not working.
  • Collective immunity
    How the spread of a disease slows down after a sufficiently large proportion of a population has been exposed to it.
  • Immune
    A person whose body can resist or fight a disease would be immune to it. Once a person has recovered from coronavirus disease, Covid-19, for example, it is thought that they cannot catch it again for a while.
  • Incubation period
    The period of time between the detection of a disease and the onset of symptom display.
  • Intensive care
    Hospital services that treat very sick patients. They are managed by specially trained health personnel and contain specialized equipment.
  • Confinement
    Restrictions on traffic or daily life, where public buildings are closed and where people must stay at home. Blockages have been imposed in several countries as part of drastic efforts to control the spread of the coronavirus.
  • Mitigation phase
    The third part of the UK’s strategy to combat the coronavirus, which will involve attempts to reduce the impact of a high number of cases on public services. This could mean that the NHS would stop all non-critical care and that the police would only respond to major crimes and emergencies.
  • NHS 111
    The NHS 24-hour online and telephone service, which provides medical advice to all who need it. People in England and Wales are asked to call the service if they are concerned about their symptoms. In Scotland they should check with the NHS inform and then call their general practitioner within office hours or 111 hours. In Northern Ireland, they should call their general practitioner.
  • Epidemic
    Several cases of disease occurring quickly, in a cluster or in different places.
  • Pandemic
    An epidemic of serious illness spreading rapidly in many countries simultaneously.
  • Phase 2
    It is at this point that the UK will begin to lift some of its lockout rules while trying to reduce the spread of the coronavirus.
  • EAR
    PPE, or personal protective equipment, is clothing and kits such as masks, aprons, gloves and protective glasses used by medical personnel, carers and others to protect themselves against infection by patients with coronavirus and other people who may be carriers.
  • Quarantine
    The isolation of people exposed to a contagious disease to prevent its spread.
  • R0
    R0, pronounced “R-nil”, is the average number of people who will catch the disease from a single infected person. If the R0 of the coronavirus in a particular population is 2, then on average each case will create two new cases. The value therefore gives an indication of the extent of the spread of the infection.
  • Recession
    This happens when there is a significant drop in income, jobs and sales in a country for two consecutive three-month periods.
  • Sars
    Severe acute respiratory syndrome, a type of coronavirus that appeared in Asia in 2003.
  • Self-isolation
    Stay indoors and avoid contact with other people, to prevent the spread of disease.
  • Social distancing
    Stay away from others, in order to slow the transmission of a disease. The government advises not to see friends or relatives other than those with whom you live, to work from home if possible, and to avoid public transportation.
  • Emergency state
    Measures taken by a government to restrict daily life while it is facing a crisis. This may involve closing schools and workplaces, restricting the movement of people, and even deploying the armed forces to support regular emergency services.
  • Statutory instrument
    These can be used by government ministers to implement new laws or regulations, or to modify existing laws. They are an easier alternative to adopting a comprehensive federal law.
  • Symptoms
    Any sign of disease, triggered by the body’s immune system while it is trying to fight the infection. The main symptoms of coronavirus are fever, dry cough, and shortness of breath.
  • Vaccine
    A treatment that causes the body to make antibodies, which fights a disease and gives it immunity against new infections.
  • Fan
    A machine that resumes breathing from the body when the disease has caused lung failure.
  • Virus
    A tiny agent that copies itself inside the living cells of any organism. Viruses can kill these cells and interrupt the body’s normal chemical processes, causing disease.

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