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The ATI air monitoring system offers the user an accurate and cost effective means of determining exposure levels of airborne chemical hazards without the complicated procedures necessary with more traditional sampling methods. With the ATI system, a credit-card sized monitoring card is simply attached in the breathing zone of an individual or placed in the area being monitored, and at the end of the sampling period, the exposure level is read directly by means of a portable electronic reader. Results are available immediately and on site enabling the user to take immediate corrective action if necessary without the delay and expense of laboratory analysis.
ATI air monitoring cards are passive devices that operate on the principle of diffusion. Air sampling is often carried out by pumping a measured quantity of air through a collection media such as charcoal or silica gel from which the targeted hazard is subsequently desorbed or extracted and its concentration determined by conventional analytical means such as chromatography. There are certain drawbacks inherent in this so called active or dynamic method in that it is expensive, inconvenient and often inaccurate due the multiple opportunities for malfunction and error. The alternative passive method uses diffusion to move the sampled air into contact with the collection media. Passive methods are attractive to the user in that they are more economical and simpler to use. The National Institute of Occupational Safety and Health (NIOSH) has recognized and addressed this issue by publishing "The NIOSH Protocol for the evaluation of Passive Monitors." This protocol sets guidelines and standards for passive monitors of all types by addressing the factors most critical to their performance such as analytical recovery, sampling rate, capacity, reverse diffusion, shelf-life, interferences and accuracy plus the effects of temperature, humidity and face velocity. All ATI monitoring cards are validated in accordance with and adhere to the criteria set forth in the NIOSH Protocol assuring the user of a viable, low cost and accurate option. The sensitivity and range of the cards are based on either the OSHA Permissible Exposure Limit (PEL) or the Short Term Exposure Limit (STEL) values.
ATI air monitoring cards operate on the principle of controlled diffusion. An airborne hazard enters the card through
a protective membrane which serves to regulate the rate of diffusion and reduce the effect of face velocity on the
performance of the card. The functional element of all ATI cards is a surface-active layer or coating called the
chromophore that has been treated with an analytical reagent specific to the hazard for which the card is designed.
Upon exposure, the chromophore undergoes a color change in proportion to the concentration of the hazard.
This color change is then scanned and converted into parts per million concentration by the ATI electronic
reader. Each ATI card is specific to the hazard for which it is designated.
The ATI electronic reader is a very accurate, portable, battery-operated combination reflective spectrophotometer and microcomputer. The instrument is programmed to perform several tasks, but its primary function is to analyze the exposure-induced color change in the monitoring cards and convert it into parts per million concentration. Each reader contains a "smart display" that walks the user through the steps required for card analysis. The keypad enables the user to easily enter pertinent data such as temperature, humidity and sampling period.
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