SINGAPORE - New N95 masks come in three sizes, and have an internal valve that can be fitted with a micro-ventilator.

They were developed by ST Engineering subsidiary Innosparks. The masks fit better, to protect wearers from airborne contaminants, and are more comfortable.

The AIR+ Smart Masks are the result of over a year of research, which included doing 3D face scans on over 800 primary and secondary school students.

The masks keep the temperature within as much as 4 deg C lower than that of a standard N95 mask.

They also reduce the level of accumulated carbon dioxide from up to 5 per cent in a standard mask to 1.5 per cent.

Increased carbon dioxide build-up can cause health conditions such as headaches and shortness of breath.

"We have arrived at an elegant solution to close the gap in today's protective masks and make a difference in people's lives," said Mr Fong Saik Hay, chief technology officer of ST Engineering.

The masks will be available at all Watsons outlets by the end of the week. The pricing will be determined by Watsons but the recommended price by ST Engineering is around $7 for a box of three masks and $29.90 for a rechargeable micro-ventilator which is sold separately.