Airports deploy thermal cameras to control Covid-19, science suggests it’s merely ‘safety theatre’

London City Airport

While flights were suspended and the terminal was closed, London City Airport installed thermal scanning cameras, which were fully operational when flights resumed from the airport on Sunday 21 June.

The cameras are located at the entrance of terminals, at the arrivals corridor and at staff entrances. As with other airports such as Heathrow, Bournemouth and Manchester, there will be signage indicating their use to passengers.

Though other airports state they are conducting trials on the use of thermal cameras, Joe Rankin, head of communications at London City Airport, said its smaller, “more manageable setup” allows the airport to use cameras without a testing phase. “It’s not a trial … it’s operational and in place,” he said.

“The camera detects an elevated skin temperature and the computer alerts the operator to that passenger,” he said. “Our system is quite instantaneous, so it’s kind of like watching a live computer feed.”

Rankin said the cameras are a permanent fixture. The airport may put more effective alternatives in place at a later stage, such as health passports or “rapid testing” to allow passengers to show they don’t have the virus.

He said these additional measures would prove more useful than a thermal check, “which obviously isn’t testing anyone for Covid-19, just temperatures”.

Each passenger will be treated on a case-by-case basis, said Rankin. “If you walk down the corridor in the terminal and you have an elevated skin surface temperature on our system, that alone does not prevent you from flying,” he said.

Once a passenger is flagged as hot, they will be given the opportunity to pause and cool down. They may be asked to have their temperature taken again with a hand-held device, and asked to answer questions about their symptoms and health.

If the passenger has Covid-19 symptoms, the airport will inform the airline. “We will make a decision in conjunction with the airline, although ultimately, it’s for the airline to determine whether the passenger travels,” said Rankin.

This policy is not universal across airports. Cornwall Airport Newquay has stated the airport itself will not allow passengers to remain in the building or board an aircraft if they are found to have a temperature of 38°C or higher.

According to the airline KLM, a passenger will be turned away from a flight if found to have a fever, though family members will still be allowed to board.

Rankin said the temperature scanning equipment stores “data such as numbers of passengers” and “temperatures being recorded”.

The system is anonymised and does not store any personally identifiable information, he said.

“It doesn’t store an image of you that can be identified and used,” he said. “It’s not tethered to your booking with the airline or anything like that.”

Rankin said any data collected would be used by City Airport for analysing trends.

Heathrow presses for international standard for health screening

Heathrow Airport CEO John Holland-Kaye is pressing for the government and the aviation industry to develop a common international standard for health screening at airports.

The airport began trials of thermal cameras to detect passengers with raised temperatures at the Terminal 2 immigration hall and Terminal 5 on 21 May.

The cameras use facial recognition technology to identify people’s faces in order to take temperature readings of multiple people as they walk by.

Heathrow records the temperature readings, gender of passengers, their age group, whether they are a child, teenager, adult or alder, how fast a passenger is walking, whether they were wearing a face mask and other information about passengers which may affect their temperature, such as whether they were holding a cup of tea.

The airport claims, however, that this information will not be linked back to individual passengers or staff.

A spokesperson for Heathrow told Computer Weekly that it would not stop passengers or refer passengers with elevated temperatures to healthcare professionals during the trial.

Heathrow declined to say whether passengers with higher temperatures would be allowed to board their flights, if the system goes live.

“There isn’t an escalation process at this stage as we are just trialling the technology to understand whether it is medically beneficial, provides passenger reassurance and is compatible with an airport environment”.

Bournemouth plans to ‘intercept passengers’

Bournemouth Airport plans to introduce multiple thermal cameras in the departures and arrivals area that will allow “border staff to intercept any passengers showing signs of a high temperature.”

Dan Cartter, head of innovation at SCC, part of the Rigby group of companies which owns Bournemouth Airport, said that airlines are considering putting clauses in their terms and conditions that would allow people with a higher temperature to be refused access to a flight.

“Until the airlines state that, the airport is largely powerless to stop people getting on the flight,” he said.

During lockdown, some 200 engineers visited the airport daily to carry out maintenance work on grounded planes. The airport used a tripod-mounted thermal camera to monitor temperatures of staff as they passed through the security area.

Cartter said the cameras, which can automatically identify and focus on a person’s face, can identify temperature to an accuracy of plus or minus 0.5°C.

The trial did not identify any engineers with elevated temperatures, said Cartter, but it reassured airport staff that the airport was looking after their safety.

With passenger flights about to resume, the airport plans to install three thermal cameras to cover two entrance doors and the arrivals gateway in the airport – though no final decision has been taken.

Airport staff will give passengers who show signs of an elevated temperature government advice on Covid-19. That could include advising them to go home and isolate or to take further tests, said Cartter.

“You need to find people at the entrance before they have interacted with other people and infected other people,” he said.

Airlines likely to be given the final say

Some European airports, including Brussels and Venezia airports, explicitly state on their websites that passengers detected with temperatures above normal will not be allowed in the terminal.

It is likely that airports will follow London City by delegating the decision to bar or accept passengers who appear to have a higher-than-normal temperature to airlines.

Unlike airports, airlines can change their terms and conditions to exclude people who do not pass temperature checks.

Many are already taking passengers’ temperatures before they board. Ryanair, easyJet and Air France, for example, warn on their websites that people who fail temperature checks may denied travel and sent home.

Yet science makes it clear that thermal screening for temperatures is not effective at diagnosing infections. Airports have used them in the past to try to control other infections – with less than impressive results.

Scientists in New Zealand, for example, found that thermal cameras were “not much better than chance” at identifying passengers who were likely to be infected with influenza.

Their chief benefit would be “to deter unwell people from travelling, or to demonstrate to their citizens that they are doing everything they can to protect population health”.

Canadian scientists reached the same conclusion over the Sars epidemic from 2002 to 2003, concluding that the predictive value of screening was “essentially zero”.

“Easily visible measures, such as thermal scanning machines, may generate a sense of confidence or reassurance that disease will be detected and prevented from entering the country,” they said.

But any sense of reassurance could be quickly dispelled when it becomes clear that cameras are failing to prevent the spread of the disease.

Profiling is ‘deeply concerning’

There are questions, too, about whether using cameras to perform mass checks on passengers is proportionate under data protection and human rights laws.

The UK’s Surveillance Camera Commissioner wrote in April that in the unique time of a pandemic, it might be proportionate to use thermal scanning as a condition of entry, if people have given consent.

But he said: “Mass use without individuals’ knowledge seems disproportionate and would require much stronger justification.”

Big Brother Watch’s Carlo said Heathrow Airport had fallen short of this requirement by failing to give passengers an obvious option to opt out of walking by the cameras.

Heathrow Airport’s website says passengers who want to avoid the cameras can talk to airport staff and ask to use a different route, but that information is hard to find, said Carlo.

She has also queried Heathrow’s plans to store anonymised data about passengers. The fact the information is recorded anonymously or, in the case of Bournemouth, isn’t recorded at all, does not make such monitoring legal, she said.

“The fact is that it is yet another kind of checkpoint, and this time a health surveillance one. We are getting more towards the monitoring of our bodies and our health. It’s about the loss of rights that will happen there and then,” she said.

EASA – thermal scanning ‘ineffective’

The European Union Aviation Safety Agency and the European Centre for Disease Prevention and Control are advising airports and airlines how to re-open as lockdown measures are eased.

Their guidance document concludes that thermal screening of passengers has many limitations and that there is little evidence of its effectiveness in detecting Covid-19 cases. 

The International Air Transport Association (IATA), a trade group which represents 290 airlines, told Computer Weekly it gives guarded support for temperature as part of a “multi-layered approach” to restarting aviation.

And IATA is clear about the limitations: thermal scanning measures the surface temperature of travellers, which is less reliable for detecting illness than measuring their core temperature.

Thermal scanning will not detect people with early-stage illness, asymptotic illness, those with symptoms that do not include fever, or those who have taken medicines such as paracetamol to reduce their temperature, it said.

Across Europe, airports including Paris, Brussels and Venice, and now the UK, are buying into thermal screening.

One exception is Germany, where Munich Airport told Computer Weekly that German health authorities have concluded that thermal screening of passengers adds negligible value to the health screening measures already in place. A spokesperson said: “General fever measurement for all arriving passengers would be ineffective.”

Guidance from the European Union Aviation Safety Agency and the European Centre for Disease Prevention and Control concludes that thermal screening of passengers has many limitations and that there is little evidence of its effectiveness in detecting Covid-19 cases

EASA warns that effective screening of passengers entails huge human laboratory and logistical resources, which will detract from the preparedness planning for a potential second wave of the Covid-19 pandemic.

Christian Ionut Panait, a medical expert for the Romanian Civil Aeronautical Authority and director of communications for EASA, said thermal screening alone should never be used as the basis for preventing someone travelling.

“As fever can have a variety of reasons, a person being identified with fever should undergo a comprehensive assessment performed by a healthcare professional to try to isolate the cause of the fever. Based on this assessment, the health authorities should decide whether the passenger may board the flight or not,” he said.

So why do it? There are three reasons, said Panait. Thermal screening might identify a passenger who did not know they had Covid-19 symptoms. Second, the technology has a deterrent effect for infected passengers who might be tempted to fly.

“And last,” he said, “it has a reassuring effect for passengers, crew members and staff that all possible measures have been taken in order for them to have a safe journey or work experience, as applicable.”

The science shows thermal surveillance is far more about making passengers feel safe than it is about controlling the risks of Covid-19.

In the words of IATA, surveys during the Covid-19 outbreak have “indicated that airline passengers are reassured by temperature screening” at airports and it could also “deter passengers who might otherwise travel while feeling unwell”.

The risk of such safety theatre is that it will divert resources and attention away from planning for and mitigating a second wave of the virus.

What the scientists say

In a February 2020 advisory note on Covid-19, the World Health Organisation (WHO) warned that “temperature screening alone may not be very effective as it may miss travellers incubating the disease or travellers concealing fever during travel, or it may yield false positive (fever of a different cause)”. It said that if temperature screening is implemented, it should be accompanied by health questionnaires, which should be promptly evaluated. Notices informing passengers what symptoms to look out for and where to seek medical support should be made available.

Epidemiologists from the Center for the Mathematical Modelling of Infectious diseases nCoV working group found that thermal scanning at airports was of limited value for preventing the spread of Covid-19. A February 2020 study found that “due to the duration of the incubation period of 2019-nCoV infection, we find that exit or entry screening at airports for initial symptoms, via thermal scanners or similar, is unlikely to prevent passage of infected travellers into new countries or regions where they may seed local transmission”. 

The European Centre for Disease Prevention and Control said in a technical report for public health authorities in May 2020 that thermal screening of passengers is a “high-cost, low-efficiency measure”. Evidence from the early phases of the Covid-19 pandemic indicates that entry screening is “ineffective in preventing SARS-CoV-2 virus introductions”. It said that while entry screening processes may help dissuade ill persons from travelling and enhance public confidence, communication needs to be carefully balanced in this case, to avoid creating a false impression of security.

The European Union Aviation Safety Agency (EASA) and the European Centre for Disease Prevention and Control advised airlines and airports on 21 May that “it should be recognised that thermal screening has many limitations and little evidence of effectiveness in detecting Covid-19 cases”. Many symptomatic people do not have a fever and a large percentage of Covid-19 infections are transmitted by people without symptoms. Thermal screening “may give a false impression of safety”, it said, and its implementation “requires public health resources that could be better invested in other measures”.

The European Centre for Disease and Control reported on 26 May that, based on current knowledge, relatively large numbers of people with Covid-19 will be in the incubation phase without symptoms while travelling. Covid-19 has an incubation period of 2-14 days, with 75% of cases developing symptoms in a period of between four and seven days. “These travellers,” it said, “will not be detected by exit or entry screening, even in a scenario assuming high-sensitivity detection of symptomatic travellers.”

A study by scientists in New Zealand in 2011 found that infrared thermal imaging scanners were not effective for mass screening passengers arriving at airports for influenza. The scanners performed “moderately well” in detecting fevers. But the cameras were “not much better than chance” at identifying passengers that were likely to be infected by influenza. The authors said governments could introduce screening for other reasons than to detect influenza, for example “to deter unwell people from travelling, or to demonstrate to their citizens that they are doing everything they can to protect population health”. But this would risk the potential loss of public confidence during a flu pandemic when it becomes clear that many infected travellers were not detected by screening when they entered the country.

In 2005, a study by Canadian scientists found that health screening passengers arriving at Canadian airports failed to detect a single incidence of Sars. The study found that because Sars had a low prevalence, the positive predictive value of screening was “essentially zero”. The scientists said that “easily visible measures, such as thermal scanning machines, may generate a sense of confidence or reassurance that disease will be detected and prevented from entering the country”. But any sense of reassurance could be quickly dispelled when the first case was detected despite screening measures.

The International Air Transport Association (IATA)’s medical advisory group published a paper on 27 April on “restarting aviation following Covid-19”. It found that temperature screening would miss many of those with early-stage illness, those who are infected but have no symptoms, or have taken medication such as paracetamol to lower their temperature. It found that research during Covid-19 “indicted that airline passengers are reassured by temperatures screening undertaken in airports”. Temperature screening needs to be done with validated equipment or manually by trained staff, but it warns that even then there will be false positives and false negatives. Screening is more likely to be useful where Covid-19 prevalence is higher, such as “returned travellers” rather than the general travel population. “It may be of some benefit, applied selectively along with other measures.”