Laser printers and photocopiers can release small amounts of pollutants into indoor air during operation. Older laser printers, in particular, could produce ozone during the printing process. Therefore, it is better not to place a printer immediately beside a person’s desk, especially in a poorly ventilated room.

Laser printers have become common in homes and offices. During printing, toner is transferred to the paper and then fixed to the paper by heat and pressure. The printing process can release particles and volatile organic compounds (VOCs), while some older laser-printer technologies could also generate ozone.

Ozone is a respiratory irritant, and exposure to elevated concentrations can cause coughing, throat irritation, breathing difficulties, and other respiratory effects. However, the amount of ozone produced varies considerably between printer models. Studies by the National Institute for Occupational Safety and Health (NIOSH) found that older printers using corona-wire technology could produce significantly more ozone, while newer printers using charged-roller technology produced very little ozone.

Laser printers and copiers can also contribute to indoor particulate matter and VOCs. The U.S. Environmental Protection Agency (EPA) recommends good ventilation when operating printers and copiers and notes that increased filtration and ventilation can reduce exposure to indoor particles from these devices.

For better indoor air quality, place printers and copiers in well-ventilated areas rather than directly beside people who spend many hours at a desk. Regular maintenance should also be performed according to the manufacturer’s instructions. If a printer produces a strong or unusual odor, excessive dust, or other noticeable emissions, improving ventilation and having the equipment inspected may help reduce exposure.

作者：Michael Chiu，MWS，CI
Previously published in Ming Pao Daily News, Updated and Revised in 2026