Print toner is a common source for which type of particles in a modern office?

• A. Ozone
• B. Visible dust particles
• C. Sub-micron respirable particles
• D. Large particle debris

Answer: (C)

Printing toner can become aerosolized during the printing process, and the particles produced are extremely small. In modern laser printers, the toner is heated in the fuser, which can aerosolize the powder into very fine particles that stay suspended in the air. These particles often fall in the sub-micron range, meaning they are smaller than one micron in size and are capable of being inhaled deep into the lungs. Because of their tiny size, they are considered respirable, which is why sub-micron respirable particles are the most accurate choice here. Ozone is a gas rather than a particle, and while some printers may emit ozone, it doesn’t represent a particulate emission. Visible dust and large debris are much bigger and less relevant to inhalation exposure from toner.