<p>Nanoparticulate (ultrafine particle) indoor air pollution is an emerging concern. Evidence points to airborne nanoparticles’ potential adverse effects, including the impact on blood pressure, the pulmonary and cardiovascular systems, cognitive performance, oxidative stress, allergen sensitization, and inflammation. Nanoparticles originate from various sources. However, no study to date investigated emissions of nanoparticles and fine particles from electric motors in household appliances, ubiquitous indoors. This study fills this knowledge gap with an investigation of incidental emission of aerosol particles from seven electric motors taken from household appliances. The appliances were made by several different manufacturers and tested at the respective appliance’s maximum and minimum power settings as intended for use by the consumer. Aerosols were continuously measured and characterized during 24-hour measurement periods using a NanoScan scanning mobility particle sizer (SMPS). Two of the seven motors (AP B and AP G) emitted very few particles, with an average total number concentration below 10&#xa0;cm^− 3. One electric motor (AP E) emitted over 170 times more aerosol particles at the maximum power setting compared to the minimum power setting. Another motor (AP A) had the highest emission of all motors at both the minimum and the maximum power settings. The total number concentration of aerosol particles exceeded 2700&#xa0;cm^− 3 and 3900&#xa0;cm^− 3 when operating two of the investigated electric motors (AP A and AP E, respectively) at the maximum power setting. We recommend that manufacturers of electric motors and household appliances test fine and ultrafine aerosol particle emissions from their products and address the problem. The design of household appliances equipped with electric motors should consider low-aerosol-emission motors and/or the installation of high-efficiency air filters in the motor air cooling duct(s) downstream of the electric motors.</p>