Mike Dinsdale of Brother UK missed the point when he said there might be concern about the fine particles getting into skin pores and into the nose (Jury still out on laser printer pollution, 3 September).

The problem with ultrafine particles, those less than 2.5 microns in diameter, is they will get into the lungs where they can cause premature death. These potentially harmful fine particles are referred to by the US Environmental Protection Agency and other national environmental programmes as PM2.5. While it is not likely that the particles from one printer will adversely affect health, those particles, along with particles currently in the air or soon to be emitted into the air, combine to adversely affect human health, especially in the young and elderly.

As a retired air pollution agency executive officer, I believe this issue needs to be studied further to determine the concentrations workers are being subjected to.

Richard Baldwin