air cleaner

OZONE LEVELS AND THEIR EFFECTS
Data from IOA
Edited by Den (Zdenek) Rasplicka - Ozone Services

ppm = Parts per million volume air concentration
0.001 ppm
Lowest value detectable by hypersensitive humans. Too low to measure accurately with elaborate electronic equipment.

0.003 ppm
Threshold of odor perception in laboratory environment, 50 per cent confidence level.

0.003 ppm to 0.010 ppm
The threshold of odor perception by the average person in clean air. Readily detectable by most normal persons. These concentrations can be measured with fair accuracy. Ozone levels measured in typical residences and offices equipped with a properly operating electronic air cleaner when outdoor ozone level is low. Infiltrating outdoor ozone could cause higher indoor concentrations.

0.020 ppm
Threshold of odor perception in laboratory environment, 90 per cent confidence level.

0.001 to 0.125 ppm

Actually the preferred method of rating air purifiers is the CADR which is based on how fast the air cleaner or air purifier cleans the air in a sealed room. This is a useful rating for comparing one air cleaner to another. The problem with this concept is that we don't live in sealed rooms. The truth is that you cannot predict how clean the air will be in your house based solely on the CADR. Nobody's home is perfectly sealed, doors open and close, and particles are generated by virtually any activity within the house. So, the number of particles floating in your home air is the result of a constantly shifting balance between particles entering the home, being generated within the home, natural settling, and active removal by air cleaning devices.

The DC1100 works on an entirely different technology than the inexpensive sensor built into your air purifier. The DC1100 is a true Laser Particle Counter that works on the same principles as the $8,000 particle counters used in pharmaceutical and semiconductor clean rooms. Those guys really do need to know how clean their air is and they don't use sensors like the one on your air cleaner. Those cheap sensors usually have an LED and photodiode arranged at an angle so the photodiode will pick up any light scattered back off the particles in the air. This design is inexpensive, but suffers from very poor signal to noise ratio and can only detect light scattered off many particles in a volume of air. In contrast, the DC1100 uses a focused laser which results in a drastically higher signal to noise ratio. This means that air can be flowed through a focused laser beam and the DC1100 is actually sensitive enough to detect individual particles.

We have yet to see a decent quality monitor on either an air purifier or an air cleaner. They typically display air quality as only "good", "clean", 5 green LEDs or some other vague way which gives the user no real information. Our tests have shown that these inexpensive type air quality sensors are inaccurate, with a tendency to drift up and down. Furthermore, they have the major limitation of only measuring the air quality right at the air purifier or air cleaner. Of course that is where the air is going to be cleanest, but unless you have the air purifier strapped around your neck it is not the air you are breathing. Besides, does it make sense to trust your air purifier to tell you it's doing a good job? So, these built in sensors are essentially a gimmick and worthless to anyone serious about improving their air quality.

Again, Natural Air is not a medical device. However, if your doctor writes a prescription for an "air cleaner" or similar description, Medicare may (and we stress the word "may") approve the expense.