WHAT IT IS
The Sanispira City and Travel disposable nasal filter traps particulate matter as tiny as 0.5 micrometers in size. Small and light, it is perfect for daily use, particularly during hazy conditions or even if you simply want to filter out dust and allergens from everyday traffic. 

Measuring 10mm in height and weighing less than 1g, it has been shown to be effective at blocking out 90 per cent of haze particles for up to six hours at normal to unhealthy PSI levels (0-300). At hazardous PSI levels (above 300), it remains effective for two to four hours. 

HOW IT WORKS 
The nasal filter, which is made from soft polymer, consists of two small domes connected by a flexible strap. To use, simply insert the domes into each nostril, ensuring they adhere properly to the walls of your nose. Coated with a patented biogel, the helix-shaped inner walls of the domes allows the air you inhale to flow upwards in a spiral manner before passing through the biogel, which in turn traps particulate matter. 

The filter has a lifespan of eight hours, and can be worn continuously or intermittently. Be sure to rinse it under running water before storing it in its protective case. 

WHAT WE LIKE
The filter was easy to wear and remove – all we had to do was tug at it gently to dislodge the entire contraption. The fit was good too, so while we could feel its presence, it wasn’t uncomfortable, even for those of us with sensitive noses. And unlike masks, which can quickly feel hot and stuffy, this didn’t obstruct our breathing. 

WHAT WE DIDN’T LIKE
While the device is touted as invisible, the strap connecting the domes is quite noticeable and looked like a nose ring of sorts, which proved to be quite distracting to the people around.

VERDICT 
A viable and convenient alternative to N95 masks. 

PRICE
Available in small and medium sizes, the filters cost $16 for a box of six, with a delivery fee of $3.80 within Singapore. Visit www.sanispira.sg for more details or to order. 

Also try: Another alternative to the Sanispira City and Travel nasal filter is the First Defense Nasal Screen, which functions like sticky tape: place the screen over each nostril with the adhesive side up. It filters up to 90 per cent of particles one micron or larger, and should be changed daily. $14.25 for a set of seven. Available at www.cypresspure.com