Most studies show that nasal cleansing removes many miseries, such as virus particles, bacteria, dust and pollen. It is a very useful adjunct to existing medications. An infection paralyzes the cilia in the nose, stagnating the removal of dirt and bacteria. A nasal rinse temporarily takes over the function of the cilia. (Combined quotes from the Volkskrant, 26-2-2017 and 17-5-2019)

Nasal rinsing may sound a little strange, but it is very easy and very effective. Nasal irrigation is included as standard treatment in ENT guidelines for treating people with chronic sinusitis and after nasal surgery, but nasal irrigation also works very well for allergies and even a common cold.
It is also important to rinse with an upward irrigation stream sprayed into the nose with slightly positive pressure so that the sinuses are properly reached. My preference is for ready-to-use sachets because then you always flush with the right concentration. The sachets also contain a combination of salts specially formulated for cleansing the sensitive nasal mucosa. Table salt is often perceived as sharp. In addition, it often contains iodine. This is irritating. Especially for the sensitive nasal mucosa. (quote from ENT supplement Telegraaf, 27-7-2017)

It is good to keep your nose clean. It is especially good for babies and children to rinse the nose with saline water, but also for adults. I also prescribe physiological salt rinses myself. That way you rinse away all the dirt, and if you swallow it, it's not a problem because you'll urinate it out again anyway. (quote from The Promise, 19-1-2019)