IC Sentinel

pdfDOWNLOAD Rev. 7/8/2014


About IC Sentinel®:

IC Sentinel® is a real-time environmental quality monitoring solution, comprised of facility-wide, low-cost, compact, multi-sensor modules.

IC Sentinel® sensors can be placed anywhere in the facility to allow real-time, 24/7 monitoring and long-term profiling. The sensors can also be conveniently moved around the facility as needed to monitor construction or problematic areas.

Infection Control

• Monitor airborne particulate count facility-wide
• Monitor differential room pressure of key areas
• Verify performance of Protective Environment rooms
• Verify performance of Operating Rooms
• Verify performance of Airborne Infection Isolation rooms
• Test for elevated humidity levels

Facilities Management

• Monitor construction and renovation areas for particulates
• Verify barrier and air filtration, effectiveness
• Monitor indoor air quality (IAQ), verify performance of HVAC
• Generate real-time alerts

Patient Satisfaction

• Monitor and baseline sound levels
• Monitor and baseline light levels
• Monitor air quality and humidity


This applications guide provides guidance in the installation and application of the IC Sentinel® product to achieve the following objectives:

• Choosing metrics on which to set thresholds
• Creating a baseline prior to setting thresholds
• Establishing a methodology for setting thresholds

This applications guide is provided to assist responsible personnel in configuring, using, and setting thresholds with IC Sentinel. This is only a guide. Facilities personnel must decide which parameters to monitor and set thresholds for, and how to communicate alarms.


The IC Sentinel® system provides you with 24/7 monitoring for the following metrics:

• Airborne Particulates
• Differential Room Pressure
• Air Quality/CO2
• Relative Humidity
• Light
• Sound

By default the sensor collects data for all of these metrics. Most facilities will be interested in all of the metrics, as they serve the Infection Control, Facilities, and Patient Satisfaction areas. There is no trade-off or compromise in collecting all of the metrics, however, individual metric collection may be disabled if desired.

If a particular metric is of no interest, and you do not want that metric displayed, or alarms generated for it, you can disable all reporting of that metric in the main options page. On the options page, simply check the N/A box in the left most column to disable all reporting of a particular metric. As with all alarms and thresholds, you can perform this from the main options page making this is a global setting which will affect all IC Sentinel® units in your facility. Or, you can perform this from an individual unit's option page, affecting that single unit.

After choosing the metrics to measure and display, the next step is to decide which metrics on which you want to generate alarms. It is quite likely that one or more metrics are of interest from a data gathering perspective, but may not be worthy of alarm generation. There is a balance between getting needed alarms and alarm fatigue, which occurs when you are overloaded with too many alarms and become insensitive to them.

You will note in the default installation, that room pressure and light are not set to generate alarms. If the alarm box is checked, any time that the threshold(s) for that metric is (are) exceeded an alarm will be generated. If the alarm box is not checked, the data for this metric is still displayed, but no alarms will be generated regardless of the data value.

Also note that in the main administrative page, when a user account is generated, you can select on which alarms each user will be notified. The alarms being discussed in this guide are all "data" alarms, not "network" or "calibration" alarms. "Data" alarms are generated when a metric exceeds a set threshold. "Network" alarms are generated when a unit is down, and not responding to the server. "Calibration" alarms are generated when a unit is due for yearly calibration. Alarm fatigue can be mitigated by ensuring the correct staff is assigned to the correct alarm categories.

Averaging of Data

Note that on both the global and individual option pages, for each metric there is an option to average, or smooth the data, with a wide range of averaging options. Averaging is very useful in controlling the "noise" and variability of the data, and reducing alarms that might be generated on very short term unique events, that the user would prefer to ignore. Averaging is a useful tool in preventing alarm fatigue.

The default averaging windows are:

Airborne Particulates: 20 Minutes
R/T Air Quality: 1 Minute (STEL is fixed at 15 mins, TWA is fixed at 8 hrs)
Differential Room Pressure: 1 Minute
Relative Humidity: 10 Minutes
Sound: 10 Minutes
Light: 10 Minutes

These averaging windows can be changed as needed by the user to obtain a slower response (increased averaging), or a faster response (decreased averaging).

When graphing and exporting data, either the averaging windows set on the threshold page can be used, or different averaging windows can be selected as desired for the purposes of graphing and exporting. Regardless of the averaging window chosen, when graphing selecting the real time button will add the real time, non-averaged data to the graph for comparison purposes, and to give a visual indication of the amount of averaging selected.

When first baselining a facility, a user can try multiple averaging values to achieve the desired response time to unusual or hazardous events, while minimizing false alarms and ignoring short transient events. Then, selecting an averaging value which is a compromise between too fast of a response and too slow of a response can be made.

Note that the averaging value can be independently chosen for each metric. Some metrics such as airborne particulates can benefit from increased averaging to ensure an accurate representation of the room, while other metrics such as room pressure can utilize decreased averaging in order to respond quickly to a loss in room pressure.

IC Sentinel® Global Options/Threshold Page

The following screenshot shows the main global options page, where a user can select which metrics to display, which metrics to alarm on, and the thresholds for each alarm. Selections made on the global options page will be applied to all IC Sentinel® Units. A similar options page is available for each individual unit, to allow the user to set thresholds differently on a per unit basis.

General guidelines from this document are also summarized at the bottom of these pages, however it is recommended that all staff responsible for setting thresholds review this document, and the references provided if needed, prior to setting thresholds.


Sample screen

Initial Threshold Setting Considerations

One methodology in setting alarm thresholds is to first baseline your facility, and then to use this data in setting thresholds. In this case, un-check every alarm box during the baselining period. Apply this setting to all units, and operate the IC Sentinel® system for an adequate length of time. You may want to collect data for at least 24 hours, and for perhaps as long as a week or more. It may be appropriate to re-visit the baseline over time, perhaps quarterly or yearly. As the data is being collected, review the values of each metric using the graphing functions available to see both daily and long term trends and issues.

If you are satisfied that your facility is operating at a normal and acceptable state during the baseline period, then setting thresholds that are slightly more tolerant than the worst case baseline values may be appropriate. This will allow you to be alerted if conditions in your facility deviate from this baseline.

Another methodology in setting alarm thresholds is to set thresholds per recommendations from international or U.S. based standards organizations, such as the ISO (International Standards Organization), OSHA (United Stated Occupational Safety and Health Administration), the FGI/AIA (Facilities Guidelines Institute/American Institute of Architects), and ANSI/ASHRAE/ASHE (American National Standard Institute/American Society of Heating, Refrigeration and Air-Conditioning Engineers/American Society for Healthcare Engineering).

Examples of metrics that can have thresholds based on standards organizations are airborne particulates, differential room pressure, air quality/CO2, and humidity.

Airborne Particulate Measurement Background

Airborne particulate count is an important metric for infection control, but can create a challenge in monitoring and determining an acceptable level. This section provides guidance on methods to set thresholds for particulate count.

The IC Sentinel® system counts airborne particulates in four channels, 0.5 um, 1um, 5um, and 10 um. Counts can be referenced to particles per cubic feet, particles per cubic meter, or particles per liter. Additionally, Counts can be reported in either a cumulative, or differential mode. These modes will be explained in more detail later in this applications note.

The IC Sentinel® system counts the absolute number of airborne particulates from 0.5um to 10um. There are two widely adopted cleanroom classifications for airborne particulates that are absolute in nature, as well as FGI/AIA guidelines that are relative in nature.

Before global cleanroom classifications and standards were adopted by the ISO, the U.S. General Service Administration's standards (US FED STD 209E) were applied virtually worldwide. As the need for international standards grew, the ISO established a technical committee and several working groups to establish its own set of standards, now known as ISO 14644-1.

These cleanroom standards were developed for critical applications, where an absolute contamination level was important, such as semiconductor processing and pharmaceutical manufacturing. This same concern with absolute levels of contamination also has application to Infection Control in healthcare institutions, such as preventing infections during surgical procedures, or preventing infections within immune compromised patient communities.

ISO 14644-1 contains 9 classes, ISO 1 through ISO 9. FED STD 209E contains 6 classes, Class 1 through Class 100,000. The following chart shows both the ISO 14644-1 and FED STD 209E standards for comparison. In all cases, these measurements are in a cumulative mode, and are absolute in nature.

ISO 14644-1 Cleanroom Standard, Maximum Particles/m^3


> 0.1um































Class 1








Class 10








Class 100








Class 1,000








Class 10,000








Class 100,000








N/A, Urban Air

In comparison to the absolute international and U.S. cleanroom standards, the FGI/AIA ANSI/ASHRAE/ASHE 170/2014 Design Guidelines recommend the following relative requirements:

• Protective Environment
  o HEPA (99.97% removal of 0.3um and greater particles)
• Class B, C Surgery, Inpatient Care, Treatment, Diagnosis
  o MERV 14 (85% removal of 0.3um, 90% removal of 1um and greater particles)
• Class A Surgery, Laboratories
  o MERV 13 (75% removal of 0.3um, 90% removal of 1um and greater particles)
• Nursing Facility
  o MERV 13 (75% removal of 0.3um, 90% removal of 1um and greater particles)
• Inpatient Hospice Facility
  o MERV 13 (75% removal of 0.3um, 90% removal of 1um and greater particles)
• Assisted Living Facility
  o MERV 7 (70% removal of 1um and greater particles)

Note that these requirements are relative to the facility fresh outside air intake particulate level.

High Efficiency Particulate Air (HEPA) filters are assigned MERVs based on their performance in accordance with standards published by the IEST (Institute of Environmental Sciences and Technology).

Minimum Efficiency Reporting Value (MERV) is a measure used to describe the efficiency with which particulate filters remove particles of a specified size from an air stream.

There are also several European health care airborne particulate standards, some of which are more thorough than the US standards, in that they consider differences between a room at rest (unoccupied) and in use (occupied as intended).

At rest measurements can be useful to determine how well the basic facility air filtration system is performing. In use measurements can be useful to determine how well the room ventilation design is performing at keeping particulates generated by personnel and their movement from entering the protected area located around the patient.

In any given operating room for example, the design of the ventilation system is such that filtered air is allowed to flow directly down onto the patient, and then wash away from the patient, and eventually be directed into return ducts outside the protected area. In this manner, particulates generated by personnel do not enter the protected area, and are instead directed into the return ducts.

The German standard DIN 1946-4:2008-12 requires a at rest limit of class H13 HEPA filter (ISO 5) in Class 1 rooms, and also specifies a degree of protection during occupied times of at least 2.0 if surgical lights are present, and at least 4.0 if no surgical lights are present. A degree of protection of 2.0 is equivalent to ISO 7, and a degree of protection of 4.0 is equivalent to ISO 5.

The French standard NF S 90-351:2003-06 and the Italian standard UNI 11425:2011-09 both place limits on airborne particulates in an at rest situation at ISO 5.

Setting Airborne Particulate Thresholds

The FGI/AIA standards are relative, requiring a certain percentage reduction with respect to the actual outdoor environment. Please refer to the IC Sentinel® Applications Guide for Healthcare Environmental Air Quality Monitoring for guidance in sampling the outdoor environment. You can baseline and continuously monitor the outdoor environment, and set thresholds which vary based upon the outdoor environment.

However, an alternative option to consider, and that we recommend, is setting low enough fixed absolute limits for healthcare facilities, based upon worldwide cleanroom standards, and a worldwide definition of nominal outdoor urban air quality, which is ISO 9.

Rather than monitoring four size channels, and setting individual limits per channel, IC Sentinel® has the unique ability to categorize airborne particulates in terms of compliance to an absolute ISO Class based standard.

The IC Sentinel® system measures particles from 0.5um to 10um, and spans the ISO cleanroom standards, as well as the FGI/AIA standards, and uses extrapolated ISO based limits for the 10um channel.

The following table shows the IC Sentinel® ISO Class limits:

IC Sentinel® ISO Class Limits, Maximum Particles/m^3
ISO/FED STD Class > 0.5um > 1um > 5um > 10um
ISO 3/Class 1 35 8.3  0.29 0.07
ISO 4/Class 10 352 83 2.9 0.69
ISO 5/Class 100 3,520 832 29 6.93
ISO 6/Class 1,000 35,200 8,320 293 69.3
ISO 7/Class 10,000 352,000 83,200 2,930 693
ISO 8/Class 100,000 3,520,000 832,000 29,300 6,925
ISO 9/Urban Air 35,200,000 8,320,000 293,000 69,255

If you assume that the outside air quality is equivalent to ISO 9/Urban Air as the reference point for the FGI/AIA requirements, it is possible to map these relative requirements into absolute limits. Using this methodology to set limits will require facilities located where the outside air is dirty to provide additional filtering to achieve an indoor particulate level that is as low as a facility located where the outside air quality is equivalent to or better than ISO 9/Urban Air.

Using ISO 9 as a fixed reference, each ISO level represents the following relative reductions in particulate levels:

• ISO 9 Reference: 100%
• ISO 8: 90%
• ISO 7: 99%
• ISO 6: 99.9%
• ISO 5: 99.99%
• ISO 4: 99.999%
• ISO 3: 99.9999%

Using the limits specified in the FGI/AIA standards, we can map these requirements into the following ISO levels:

• A HEPA limit of 99.97% removal based upon ISO 9 as a reference would result in using an ISO 5 limit (99.99%).
• A MERV 13/14 limit of 90% removal based upon ISO 9 as a reference would result in using an ISO 8 limit (90%).

Using the above IC Sentinel® ISO Class Limits, we recommend using IC Sentinel® in the ISO Class alarm mode, with the ISO Class alarm thresholds set as follows:

• Protective Environments
  o IC Sentinel® ISO Class 5 (At Rest)
  o IC Sentinel® ISO Class 5.5 to 6 (In Use)
• Class B, C Surgery
  o IC Sentinel® ISO Class 5 (At Rest)
  o IC Sentinel® ISO Class 5.5 to 6 (In Use, Invasive Implant Procedures)
  o IC Sentinel® ISO Class 6 to 7 (In Use, General Procedures)
• Class A Surgery, Inpatient Care, Treatment, Diagnosis, Laboratories
  o IC Sentinel® ISO Class 8 (In Use)
• Nursing Facility
  o IC Sentinel® ISO Class 8 (In Use)
• Inpatient Hospice Facility
  o IC Sentinel® ISO Class 8 (In Use)
• Assisted Living Facility
  o IC Sentinel® ISO Class 8 (In Use)
• Any other location requiring tight control
  o IC Sentinel® ISO Class 6-7 (In Use)

Of course, you can choose to not use the IC Sentinel® ISO Class of airborne particulate thresholds. Custom limits can be set in each of the particle count size bins, 0.5um, 1um, 5um, and 10um. Additionally, these thresholds can be calculated in either Cumulative or Differential mode.

The ISO based measurements are inherently made in the Cumulative mode. The cumulative counting mode includes all particles that are equal or greater to the channel size. For example, if a 7um particle is counted, it would yield one count in each of the 0.5um, 1um, and 5um channels, and a zero count in the 10um channel.

The differential counting mode includes all particles that are equal or greater than the channel size, but less than the next greater channel size. For example, if a 7um particle is counted, it would yield a zero in the 0.5um and 1um channels, a 1 in the 5um channel, and a zero in the 10um channel.

The default IC Sentinel® mode of operation is ISO Class 8 mode, which is a Cumulative mode of operation.

In any given facility, it will likely be necessary to set each IC Sentinel® unit thresholds separately. For example an Operating Room would require lower thresholds, and a construction area or general treatment room would have higher thresholds. One can use the global threshold setting to set all units to the most commonly used threshold, and then individually adjust units as needed.

The airborne particulate sensor normally operates with a 50% duty cycle, one minute on and one minute off, to allow for precise sound measurements to be made during the off cycle. In environments such as operating rooms if noise measurement is not needed, the particulate pump can be set to always run, which decreases the measurement uncertainty of the particulate measurement.

This pump can be set to off, which disables airborne particulate measurements and improves the accuracy of the sound measurement. The available pump modes are : 50% duty cycle (default), always on (sound measurement disabled), and always off (airborne particulate measurement disabled).

Differential Room Pressure Thresholds

Certain rooms within a healthcare institution must be pressurized, either positively or negatively. Examples of positively pressurized rooms are OR (Operating Room) and PE (protective environment) rooms. Examples of negatively pressurized rooms are AII (Airborne Infection Isolation) rooms and construction areas.

The FGI/AIA ANSI/ASHRAE/ASHE 170/2014 Guidelines require the following differential pressure limits to be maintained:

• AII Rooms: Negative 2.5 Pa/0.01 in WC
• Bronchoscopy Procedure/Sputum Induction Rooms: Negative 2.5 Pa/0.01 in WC
• PE Rooms: Positive 2.5 Pa/0.01 in WC
• Class B/C OR Rooms, Operating/Surgical Cystoscopic Rooms, Caesarean Rooms: Positive 2.5 Pa/0.01 in WC
• Hospital Construction Barriers: Negative 7 Pa/0.03 in WC.

The CDC (Centers for Disease Control and Prevention) EIC MMWR recommends:

• PE Rooms: >Positive 8 Pa
• AII Rooms:
Note that these should be tested for pressure on an on-going basis, and pressurization should be maintained at all times.

For rooms requiring differential room pressure to be maintained, we recommend setting an alarm threshold at least 5 Pa in general, at least 8 Pa for PE rooms and construction barriers. Be certain to properly select either a negative or positive threshold, as appropriate.

Note that the thresholds for differential pressure are very small, and difficult to measure. The IC Sentinel® pressure sensor comes calibrated from the factory, but differences in physical orientation (horizontal on a desk/cart versus vertical in the wall mount bracket), and shifts due to physical shipping and handling can cause the zero point of the sensor to shift slightly. While this shift is small with respect to the limits above, we recommend that each IC Sentinel® being used for pressure measurement be re-zeroed once after final installation. This can be executed from an individual unit's options page.

For further information regarding how to measure differential pressure, please see the IC Sentinel® Differential Pressure Accessories Application Guide.

Air Quality/CO2 Thresholds

Although normal levels of CO2 are considered harmless, under the right conditions CO2 can cause adverse health effects. High concentrations of CO2 in confined areas can be potentially dangerous. CO2 may act as an oxygen displacer in confined spaces and cause a number of reactions. These reactions include, but are not limited to: dizziness, disorientation, suffocation, and under certain circumstances, death. CO2 is measured in terms of ppm, parts per million, by volume of air.

CO2 is a good indicator of proper building ventilation and indoor air exchange rates. It is measured in buildings to determine if the indoor air is adequate for humans to occupy the building.

The following are symptoms from differing concentrations of CO2:

• 2,000 ppm: Shortness of breath, deep breathing
• 5,000 ppm: Breathing becomes heavy, sweating, pulse quickens
• 7,500 ppm: Headaches, dizziness, restlessness, breathlessness, increased heart rate and blood pressure, visual distortion
• 10,000 ppm: Impaired hearing, nausea, vomiting, loss of consciousness
• 30,000 ppm: Coma, convulsions, death

The IC Sentinel® system reports CO2 three ways, R-T (Real-Time), STEL (Short Term Exposure Limit), and TWA (Time Weighted Average). These three CO2 measurements differ only by how long the measurement is integrated over. R-T results are integrated over 15 seconds, STEL measurements are integrated over 15 minutes, and TWA results are integrated over 8 hours.

OSHA has set the following PEL (Permissible Exposure Limits) for occupied buildings:

• STEL: 30,000 ppm
• TWA: 5,000 ppm

The default IC Sentinel® CO2 limits are:

• R-T: 1,250 ppm
• STEL: 1,250 ppm
• TWA: 1,250 ppm

These can be changed, or not selected for alarm, as deemed appropriate.

Relative Humidity Thresholds

The FGI/AIA ANSI/ASHRAE/ASHE 170/2014 Guidelines require the following relative humidity limits to be maintained:

• Critical and Intensive Care: 30-60%
• Endoscopy Procedure Rooms: 30-60%
• Class B/C Operating Rooms: 20-60%
• Treatment/Recovery Rooms: 20-60%
• PE/AII Rooms: Max 60%

The default IC Sentinel® relative humidity limits are 30-60%. These can be changed, or not selected for alarm, as deemed appropriate.

Note than when an IC Sentinel® unit is first powered on, there is a 30 minute delay in the measurement and reporting of relative humidity to allow the humidity sensor to stabilize.

Light Thresholds

An ambient light sensor is provided that approximates the human eye response to visible light. Rejection to infrared and 50/60 Hz lighting ripple is also provided. The light level is displayed as Lux. The light sensor input port is located on the top of the unit. Ensure that this port is facing the main desired source of light for best operation.

An alarm can be set for the desired light level, configurable for both low light or high light thresholds. The default IC Sentinel® setting is for this alarm to be disabled, with limits of 200 Lux and 2000 Lux. These can be changed, or not selected for alarm, as deemed appropriate.

Sound Thresholds

An audio sound sensor is provided. It features a wide dynamic range logarithmic amplifier, and an A-Weighted audio filter, designed to approximate the human ear response to different sound frequencies. The audio level is displayed as dB (decibel) sound pressure level, A-weighted (dBA SPL).

This sensor can be used to provide a quantitative baseline of the noise level within a healthcare environment. Normal speaking voices are approximately 65 dBA. Levels above 85 dBA can permanently damage hearing. The NIOSH (National Institute for Occupational Safety and Health) has established a permissible exposure time of 8 hours at a level of 85 dBA SPL.

The FGI/AIA ANSI/ASHRAE/ASHE 170/2014 Guidelines supply the following sound guidelines:

• Separate limits should be set for day and night periods.
• The night limit should be 5 to 10 dBA below the day limit.
• Daytime limits typically vary between 55 and 65 dBA.

An alarm can be set for the maximum sound level desired. The default IC Sentinel® threshold is 80 dBA SPL. This can be changed, or not selected for alarm, as deemed appropriate.

When airborne particulates are also measured, the sound measurement is de-sensitized during the airborne particulate pump cycle. This pump can be set to off, which disables airborne particulate measurements and improves the accuracy of the sound measurement. The available pump modes are : 50% duty cycle (default), always on (sound measurement disabled), and always off (airborne particulate measurement disabled).


AIA: American Institute of Architects, www.aia.org
ANSI: American National Standards Institute, www.ansi.org
APIC: Association for Professionals in Infection Control and Epidemiology, www.apic.org
ASHE: American Society for Healthcare Engineering, www.ashe.org
ASHRAE: American Society of Heating, Refrigeration, and Air-Conditioning Engineers, Inc., www.ashrae.org
CDC: Centers for Disease Control and Prevention, www.cdc.gov
DIN: Deutsches Institut fur Normung, www.ansi.org
FGI: Facilities Guidelines Institute, www.fgiguidelines.org
IEST: Institute of Environmental Sciences and Technology, www.iest.org
NF: Association Francaise de Normalisation, www.afnor.org
NIOSH: National Institute for Occupational Safety and Health, www.cdc.gov/niosh
OSHA: United States Occupational Safety and Health Administration, www.osha.gov
TJC: The Joint Commission, www.jointcommision.orgUNI: Ente Nazionale Italiano di Unificazione, www.uni.com