There are many brands of air purifiers with ionizers that produce a very tiny amount of Ozone as a by-product. Earlier there were even Ozone generators sold as air cleaners. Many embassies and organizations in India have purchased these machines in large numbers to help protect their employees and families. Are they, in fact, effective and are they safe?
These machines can be effective in reducing particulate matter from the air. They use an electrostatic charge to create “negative ionization” which further causes “coagulation” of the very small particles and hence they are able to get high-efficiency filtration of particulates with low-quality filters. Lower quality filters mean less pressure drop and better airflow.
Unfortunately, the two issues that most people don’t realize are as follows:
With lower quality filters, the efficiency of the filtration is high when the filters are new as the air delivery is high. But as the filters get choked quickly, efficiency drops quickly and one must change the filters more frequently on these machines (as compared to any machine that does not do the negative ionization). This adds up quickly and the life-cycle cost of these machines is typically VERY high.
More importantly, as per the US EPA, these machines are categorized as “safe” machines from an Ozone production perspective. Ozone at the ground level is a very harmful oxidating agent that causes higher levels of asthma and lung problems. These machines only produce a very small amount of Ozone – much less than the safe limit of 50 ppb. This is great in countries like the US where they do NOT have an ambient Ozone problem. However, in India, we have a very big problem with ambient Ozone. Hence, if we add a small amount of Ozone to an already existing problem, we are making the problem worse. We need to get technologies that reduce or eliminate the indoor air quality problem and not technologies that add to the problem. And given that these machines are typically used in closed non-ventilated spaces, the Ozone accumulation can get even higher over time.