If your office desk is in close proximity to a laser printer that is heavily used, you should move it somewhere else.

The laser printing process involves the emission of ultrafine particles, less than 0.1 micrometres in diameter. When the printer toner and paper pass over the hot printer roller, chemicals – known as volatile organic compounds – are released into the air. Here they react with ozone and condense, forming the particles.

Whether these particles are harmful is the subject of ongoing research. However, there is evidence that similar-sized particles from other sources may damage our hearts and lungs: vehicle exhausts, burning wood and even cooking.

Not all the printers release the same amount of particles. Some create 1000 times more particles than others, temperature being a crucial element. But it is always a good idea to keep a printer in a well ventilated room, not too close to working stations.