 | Howard McDaniel is president and owner of Even-Temp of Wichita, Inc... Howard started Even-Temp of Wichita, Inc. in 1991. Even-Temp is a fully-licensed and bonded residential and commercial mechanical contractor in Wichita and the surrounding areas. Howard has been a member of the Kansas Cooling Contractors Association (aka K.C.C.A.) since 2001. He is also a member of the B.B.B. and Chamber of Commerce. Howard’s education includes graduate of Pittsburg vocational technical college and 5 years of schooling through the Local 171 Plumbing apprenticeship school. Howard built Even-Temp to what it is today. He started his business working many hours, night and day, by himself to a successful business with over 20 employees. Howard is an honest, fair and considerate business man, which is proven by the number of customers he has and by the number of them that have been with him for over 10 years. Howard can be contacted at his office at (316) 262-2277, fax at (316) 262-5366, or you can e-mail him at Howard@eventemp.com. |
Home Improvement
2007-09-01 09:59:00
Difficulties with ozone exposure
Answer: The actual concentration of ozone produced by an ozone generator depends on many factors. Concentrations will be higher if a more powerful device or more than one device is used, if a device is placed in a small space rather than a large space, if interior doors are closed rather than open and, if the room has fewer rather than more materials and furnishings that absorb or react with ozone and, provided that outdoor concentrations of ozone are low, if there is less rather than more outdoor air ventilation.
The proximity of a person to the ozone generating device can also affect one’s exposure. The concentration is highest at the point where the ozone exits from the device, and generally decreases as one moves further away.
Manufacturers and vendors advise users to size the device properly to the space or spaces in which it is used. Unfortunately, some manufacturers’ recommendations about appropriate sizes for particular spaces have not been sufficiently precise to guarantee that ozone concentrations will not exceed public health limits. Further, some literature distributed by vendors suggests that users err on the side of operating a more powerful machine than would normally be appropriate for the intended space, the rationale being that the user may move in the future, or may want to use the machine in a larger space later on. Using a more powerful machine increases the risk of excessive ozone exposure. Ozone generators typically provide a control setting by which the ozone output can be adjusted. The ozone output of these devices is usually not proportional to the control setting. That is, a setting at medium does not necessarily generate an ozone level that is halfway between the levels at low and high. The relationship between the control setting and the output varies considerably among devices, although most appear to elevate the ozone output much more than one would expect as the control setting is increased from low to high. In experiments to date, the high setting in some devices generated 10 times the level obtained at the medium setting (US EPA, 1995). Manufacturer’s instructions on some devices link the control setting to room size and thus indicate what setting is appropriate for different room sizes. However, room size is only one factor affecting ozone levels in the room.
In addition to adjusting the control setting to the size of the room, users have sometimes been advised to lower the ozone setting if they can smell the ozone. Unfortunately, the ability to detect ozone by smell varies considerably from person to person, and one’s ability to smell ozone rapidly deteriorates in the presence of ozone. While the smell of ozone may indicate that the concentration is too high, lack of odor does not guarantee that levels are safe.
At least one manufacturer is offering units with an ozone sensor that turns the ozone generator on and off with the intent of maintaining ozone concentrations in the space below health standards. EPA is currently evaluating the effectiveness and reliability of these sensors, and plans to conduct further research to improve society’s understanding of ozone chemistry indoors. EPA will report its findings as the results of this research become available.
