If you were among those who had no clue about SpO2 (Saturation of peripheral oxygen) in 2019, you were not alone. That’s changed and how. COVID-19 has created more awareness for SpO2 or oxygen saturation levels than ever before. SpO2 monitoring has become a big part of the sales pitch for many wearables in a post-pandemic world

The basics: SpO2 refers to oxygen saturation or in simple terms an estimation of the amount of oxygen in the blood. The ideal blood oxygenation level necessary to supply the energy your muscles need to function is around 95 to 100% (90 to 100% is acceptable)

Why it matters now: levels below 90% are a sign of poor blood oxygenation or hypoxia that is a cause for concern. If a person has a mild case of COVID-19 and is self-isolated at home, SpO2 readings are useful to monitor any dip in oxygen levels. SpO2 readings are equally useful for those with sleep apnea (a sleep disorder in which breathing repeatedly stops and starts) as well as those with active lifestyles; one reason why many fitness-focused wearables like Garmin have kept tabs even in a pre-pandemic world.

Keeping tabs: if you’ve been to a gym or hospital (for a COVID vaccine) or even the odd hotel or restaurant over the last 12 months you might had a device clipped to your finger. SpO2 is measured by Pulseimetry, a non-invasive method that emits and then absorbs a light wave passing through blood vessels. These clinical, clip-on devices that attach to your finger (or even your earlobe) depend on the variation of the light wave passing through the finger; this generates the value of the SpO2 measurement. The degree of oxygen saturation causes variations in the blood’s colour.

Wearable tech: Since 2020 we’ve seen a whole host of smart watches and fitness trackers embedded with Optical SpO2 sensors. These wearables typically use red and infrared light sensors that analyse the colour of your blood. The degree of oxygen saturation causes variations in the blood’s colour. During a blood oxygen measurement, the back crystal on the Apple Watch 6 shines red and green LEDs and infrared light onto your wrist. Photodiodes then measure the amount of light reflected back. Advanced algorithms depend on this data to calculate the colour of your blood. This colour determines your blood oxygen level — bright red blood has more oxygen, while dark red blood has less.

 

Smartwatches with SpO2 sensors

 

Apple Watch 6: offers both on-demand measurements that can be taken when the user is still and periodic measurements when they are inactive including during sleep. The Blood Oxygen sensor on the sixth-gen Apple Watch compensates for natural variations in the skin and improves accuracy by employing four clusters of green, red, and infrared LEDs, along with the four photodiodes on the back crystal of  Apple Watch, to measure light reflected back from blood. (Rs 40,900 onwards).

 

Apple Watch 56

 

Samsung Galaxy Watch 3: it’s sleek yet sturdy and can flit effortlessly from boardroom accessory to gym companion. It’s loaded with wellness features. This wearable uses red LED and infrared rays to estimate your SpO2 levels. The SpO2 sensor works seamlessly and on demand. (Rs 29,600 onwards)

 

Samsung Galaxy Watch 3

 

Fitbit Versa 2: doesn’t offer spot checks, it’s SpO2 sensors are linked to sleep data. A new watch face displays your SpO2 readings almost by default. This feature is also available on the first-gen Fitbit Versa (Rs 14,000 onwards)

 

 

OPPO Band Style: keeps a tab on your blood oxygen levels, you can view these numbers on the Hey Tap Health App. OPPO claims that the band runs non-stop SpO2 monitoring (28,800 times) during an eight-hour sleep cycle. You do have the option of ‘on demand’ readings too. (Rs 2,799)

 

 

OnePlus Band: one of the cheapest devices to offer SpO2 tracking. It works quite well as long as you follow simple instructions like fastening the band tight and staying still with your hand on a flat surface as it measures your blood oxygen levels. The companion App (OnePlus Health) is pleasing on the eye and offers an elaborate dashboard. (Rs 2,499)

 

 

Amazfit T-Rex Pro: unmistakably rugged, geared for all your outdoor pursuits. This smartwatch has 15 military-grade certificates to back its rugged credentials. It’s designed to resist extreme environments and withstand extreme temperatures. It also offers SpO2 monitoring. (Rs 12,999)

 

 

Garmin Fenix 6 Pro Solar: hardcore fitness buffs will appreciate the reliable Pulse Ox Blood oxygen sensor in this wearable. It also measures how your body’s oxygen levels adjust to thinner air at higher altitudes (Rs 88,490)