Mr. Simon Jones:

There is a hierarchy of control in ventilation. The first phase involves removing the pollutant in the first instance, which requires the replacement of stale air with air that is typically from outdoors. If that outdoor air is not safe enough, filtered outdoor air is used. That is the first defence. The second is when polluted air cannot be removed wholesale from a space. In that case, recirculation through filtering of the space is the next solution. This is where we start to talk about HEPA filters, be they portable or part of the building. Where air is recirculated, the pollutants are passed through effective filters to deal with them. The next phase is to deactivate the substance one is seeking to prevent from entering. This is where we start to talk about technology such as UV lights, which can kill viruses.

All these technologies, in the right circumstances and appropriately used, have been able to show complete effectiveness at removing pollutants from spaces but they have to be appropriately specified. One has to understand what one is trying to achieve with them in the given space. A good example is HEPA filter recirculation through portable devices. Those devices can typically remove close to 100% of viruses in a single air pass. While they are very effective, their ability to be effective in a space depends on how much air they are capable of moving in a given period. Therefore, they have to be appropriately sized and located in the right spots, and so it goes. The simple answer to the Deputy's question is that these technologies are capable of dealing with almost every issue we face, be it Covid or another pollutant, in these spaces; the challenge is using them appropriately.