Ultrasonic Humidifiers, a Source of PM2.5?
Outdoor air quality is unpredictable. The weather and atmospheric conditions can change from one day to another; environmental pollution, car density, and even daily activities like smoking and lighting fires can affect the PM2.5 concentrations. In a sense, indoor air should be easier to maintain clean and breathable. But what if there is a silent enemy inside your home? Ultrasonic humidifiers may significantly contribute to PM2.5 levels inside your home.
How do they affect me?
Ultrasonic humidifiers use a piezoelectric transducer to generate ultrasonic vibrations that create tiny water droplets, then circulated into the air by a fan to increase the overall moisture levels. Because of this delivery method, impurities in the water become airborne. Even after the water droplets have evaporated, this fine particulate matter (PM2.5) remains in the air, increasing the PM2.5 concentrations to hundreds of μg m-3 in the area, which can then circulate into the entire household.
The type of water used in the humidifiers has also been a research topic. Various sources claim that tap water has little to no effect on people's health, given that few microorganisms present in the water could pose a threat to human health. However, according to the article Particulate matter emitted from ultrasonic humidifiers - Chemical composition and implication to indoor air (EPA, 20202), once they are airborne as PM2.5, these tiny particles can enter deep into our respiratory tract, causing short-term and long-term health risks.
Experts recommend using distilled water to minimize the risk of increased PM2.5 levels while using an ultrasonic humidifier.
Suppose you live in a dry area and require a humidifier. In that case, the EPA says "evaporative" or "steam vaporizer" humidifiers may spit out fewer microorganisms than "ultrasonic" or "cool-mist" machines. So consider this when purchasing your next device.
Your indoor PurpleAir sensor could also help you monitor the air quality inside your home. The glowing led light will indicate the air quality. If your sensor is showing high concentrations of PM2.5 and you don't know what to do, consider following these useful tips.