Are we using the right thermal body scanners for screening temperature as a measure to prevent the spread of Covid-19? May be not.

In fact, there seems to be a lack of clarity on these thermal scanning devices. Multiple thermal scanners reviewed by BusinessLine reported different temperatures for the same human body. The temperature displayed on these scanners varied from 87°F to 97.5°F within a span of 30 minutes. No other metrics were changed between these tests.

Asked about the varying temperatures exhibited by these devices, an online retailer said, “We don’t know about the technical specifications of these devices, we just act as traders for these thermal scanners. The product is manufactured and imported from China and that is all we know.”

Most of the thermal scanning devices are sold out on online platforms, as the country gears to tackle the Covid-19 crisis.

Restricting entry

These scans are being used to identify potential patients of Covid-19 who are prevented them from entering crowded establishments such as government offices and even residential housing societies. A large number of residential housing societies have also deployed these scanners and are keeping a check on visitors.

According to the US National Library of Medicine, the average normal body temperature is generally accepted as 98.6°F (37°C). But some studies have shown that the ‘normal’ body temperature can have a wide range — from 97°F (36.1°C) to 99°F (37.2°C). A temperature over 100.4°F (38°C) is most often presumed to be fever caused by an infection or illness. The human body temperature also normally changes throughout the day.

Correct way to use scanners

“The correct way to use these thermal scanners is to place the subject at a distance of 1-3 cm from the scanning device. If the person being scanned is beyond this distance, the air temperature is also factored in by the device in its reading. This gives a false sense of comfort to the assessors and the people being scanned. This can also be the reason why so many devices are reporting human body temperatures around 88°F or 90°F, much below the actual temperatures,” said Gaurav Khurana, CEO at Sahyog Wellness.

“Many people are using infrared thermometers that are used in coal mines. They are not recommended for the human body and are very harmful. The devices being sold in the Indian market are all manufactured outside India and imported from there. Since they use laser technology, the government does not allow them to be made in India; hence the import-reliance. Due to the sudden surge in demand after the Covid-19 outbreak, most stocks have already been depleted. Fresh stocks are in transit but they are facing logistic hurdles because of the lockdowns. The government should move to ease import restrictions so that these medical devices can be procured and domestic demand met,” Khurana added