Pharmaceutical scientist and medical device expert Sir Ray Avery says Director-General of Health Dr Ashley Bloomfield is "100 per cent correct" in warning that Covid-19 community transmission is now inevitable, and that families should start stocking up on their own personal supplies of masks.

There was a huge amount of misinformation regarding the best masks to use for the prevention of community transmission of pathogenic diseases such as Covid, his advice being based on more than 30 years' experience in reducing hospital-acquired infections and the manufacture of implantable medical devices free from microbiological contamination. He has carried out testing at hospitals in Singapore, Eritrea and Nepal.

"Firstly, there is the belief that Covid is only transmitted via aerosol droplet formulation, but this is not true," he said.

"In confined spaces Covid can be airborne for distances far greater than two metres, so having the right mask is imperative to protect people and their families from infection."


The most common masks used were cheap surgical varieties that were designed to prevent the wearer from spreading their own bio-burden bacteria to others via droplet formation. The problem was that such masks did not seal around the face, and exhaled air, contaminated with Covid, could escape around the edges, infecting someone in the immediate environment.

Nor did surgical masks filter out airborne bacteria, yeasts, moulds and viruses, so they would not protect against infection by Covid-19.

The gold standard for the prevention of Covid transmission was the N95 NIOSH-approved respirator mask that was universally used by frontline Covid medical staff.

"The important wording to look for when buying a mask to prevent contracting covid is a NIOSH-approved N95 mask," Avery said.

"Its certification is given only to manufacturers who demonstrate that their masks filter out bacteria and viruses and are free from harmful chemicals and bacteria, and most importantly provide a good face-fit seal. If the mask does not seal well around the face then it is about as useful as using a condom with holes in it.

"In New Zealand there has been a plethora of mask manufacturers popping up making masks locally, but many that we have tested don't have a good face fit and have no protection from contracting or spreading Covid-19.

"If people want protection from Covid and help protect New Zealand's team of five million, we must all buy a NIOSH-approved N95 mask and put it on. There will be an aluminium band around the nose area, so press this hard against the nose and face then cup the hands around the mask and blow hard into it If the mask is not fitted correctly, air can be felt coming out, usually around the upper part of the mask, so then reposition the mask until the seal is right, which will provide protection against Covid infection via airborne transmission, and will also protect others close by.

"The average person produces between 10 and 30 million bacteria per hour in a closed room environment ,so wear a mask and be a good Kiwi."