Handheld Meter Testing for IAQ Solutions PDF

# Handheld Meter Testing ## Chapter 5 - Handheld Meter Testing ### Introduction A measurement and testing process is necessary to investigate IAQ complaints and resolve problems. While measurement processes are important, sampling for specific chemical contaminants is not always the first step fo...

# Handheld Meter Testing ## Chapter 5 - Handheld Meter Testing ### Introduction A measurement and testing process is necessary to investigate IAQ complaints and resolve problems. While measurement processes are important, sampling for specific chemical contaminants is not always the first step for investigating a suspected IAQ issue. In many cases, a complaint can be resolved without any contaminant testing. Basic air properties and indoor air quality must be understood before addressing complaints and testing for contaminants. Handheld meters are used to test the levels of some contaminants. ### IAQ Complaints Complaints often vary from vague to precise and can sometimes lead to legal problems. Legal liability is a major concern for a company or building manager. Following the proper IAQ complaint procedures can help protect a company from legal issues. During an inspection process, **all ideas and actions should be documented in a work order.** A holding file should be established for these records. Notes from the work order should be recorded in an IAQ log, along with any HVAC system adjustments needed to meet acceptable air quality levels. **An IAQ log, with detailed measurements and facility notes, may refute claims made in subsequent litigation.** ### Complaint Procedure When a complaint is received, the response should be immediate. **Figure 5-1** describes the steps for a quick response: 1. Responding immediately increases the ability of stationary engineers to resolve IAQ problems before they become unmanageable. 2. Quick response saves money and helps maintain good relations with building occupants. The stationary engineer should speak with the occupant who filed the complaint. The person handling the complaint should be polite, concerned, and ask for further details about the nature of the complaint. All contributing factors that require investigation should be written down. The following steps should be followed during the investigation: 1. Establish when the symptoms first occurred. This information assists with evaluating possible reasons for the occupant’s complaint. 2. Conduct a visual inspection of the building occupant’s space to get a clear picture of the area and note any obvious issues. 3. Check items around the complaint location, such as obstructed grills, occupancy level, occupant activity, equipment, odors, lighting, and noise. 4. Examine the temperature and relative humidity in the area where the occupant feels symptoms most strongly. 5. Calibrate or repair any thermostats or sensors operating improperly. 6. Check the airflow from nearby diffusers and at the complaint source. 7. If airflow is not at the correct level, trained personnel check the airflow at every diffuser on the HVAC loop and rebalance the entire loop. 8. Examine the space conditions for problems such as water damage, mold or mildew, odors, dust, open chemicals products, or damaged walls. 9. Evaluate space activities and timing patterns, including office and custodial tasks. 10. Record any products used in the area, such as cleaning products, glues, correction fluid, perfumes, and tabletop air fresheners. 11. Review the chemical inventory and MSDSs for all the products used in the facility. 12. Note any changes made in the complaint area, such as the installation of new office partitions, the addition of laser printers, and the addition of people working in the space. 13. Inspect pathways leading out of the area if no obvious contaminants are found in the complaint area. 14. Review the contaminant pathway and accompanying prints for insight into the problem. 15. Evaluate spaces connected to the complaint area for contaminants. 16. If the initial steps do not solve the problem, conduct a more thorough inspection of the HVAC system. **When the problem is resolved, all forms used and a brief account of actions taken should be filed in the incident log.** The facility’s procedure for reporting all findings to the building occupants should be followed. Occupants should notify the appropriate authority about any recurring problems. #### IAQ Fact Gathering information from the complainant is necessary, but it doesn’t always lead to the problem source. It is important to remember that the true origin of an IAQ problem is often not the source that was initially expected. ### IAQ Compliant Investigation Procedures **Figure 5-1** shows an IAQ Compliant Investigation Procedure: 1. Respond to complaints immediately 2. Speak to the person who generated the complaint 3. Investigate changes, such as new partitions, addition of laser printers, and people in the complaint area 4. Document all work and information 5. Conduct visual inspections 6. Check airflow 7. Investigate conditions for water, mold and other problems 8. Investigate complaint space activities and timing patterns 9. Review any prints and possible contaminant pathways 10. Review all repairs and work orders for the complaint space and adjoining areas 11. Follow facility procedures for reporting findings to building occupants 12. Fill out and file all forms dealing with the resolution of occupant's complaints ### Measurement and Testing Measurements should always be taken when a facility or building first opens to establish readings as part of a preventive maintenance (PM) program. Initial measurements provide baseline information about the facility, which helps when troubleshooting IAQ complaints. When establishing baseline information, it is necessary to identify sample testing areas that represent the different parts of the facility. Testing may need to be performed more frequently during the baseline measurement program to obtain a good facility profile. #### Environmental Conditions and Contaminants Environmental conditions and the presence of chemicals and gases within a space can be easily measured with various test instruments (meters). **See Figure 5-2** Test intervals vary depending upon the kind of PM program and visual inspection schedule that a facility or building has in place. #### IAQ Test Instrument Measurements **Figure 5-2** shows measurable conditions and contaminants that can be measured easily with basic test instruments: | Measurable Conditions | Measurable Contaminants | |---|---| | Temperature | Nitrogen dioxide | | Pressure | Carbon monoxide | | Relative humidity | Carbon dioxide | | Air volume | Ozone | | Air velocity | Formaldehyde | #### Sampling Program It is essential to test the outdoor air when establishing a sampling program. Testing should also be used to answer questions raised by specific symptoms or to confirm a hypothesis based upon an initial investigation. For example, a formaldehyde problem can be confirmed by testing for itchy skin and watery eyes in a building where new furniture was installed. Some testing may also be part of a regularly scheduled air-sampling strategy to log baseline measurements of air quality. #### Specialized Tests Specialized tests are available but the majority of IAQ issues can be resolved by testing for standard air conditions and common contaminants. If additional tests are required, facility management can consult with outside professionals. #### Traceability Traceability is the unbroken chain of paperwork relating a test instrument’s accuracy to a known standard. In the United States, national standards for weights and measures are maintained by the National Institute of Standards and Technology (NIST). The instrument accuracy can be proven with a certificate of traceability. While not every instrument or situation requires traceability, it is helpful to provide defensible results. ### IAQ Direct-Reading Test Instruments When conducting complaint investigations, personnel may use direct-reading instruments, chemical detector tubes, airflow measurement devices, and passive monitors. *Direct-reading instruments,* also known as handheld meters, are capable of measuring general building conditions such as air temperature, airflow, relative humidity, carbon dioxide and carbon monoxide levels. #### Handheld Meter Applications Some handheld meters are capable of testing for multiple building conditions. For complaint investigations, measurements are taken both in the complaint area and outside the complaint area. When checking ventilation adequacy, measurements should coincide with known peak occupant concentration periods. Periodic sampling helps determine when the pollutant peaks occur. #### Calibration It is best to sample temperature, relative humidity, carbon dioxide, and carbon monoxide at periodic intervals. Every section of a facility should be part of the sampling. The frequency of the samplings is determined mainly by the type and size of the facility. The same instruments (for reading comparisons) are always used for IAQ samples, and instruments must be kept properly calibrated. All handheld meters must be calibrated on a regular basis. #### Calibration Considerations * **Carbon monoxide meters** usually require monthly calibration. * **Carbon dioxide meters** require calibration once a year. **See Figure 5-3** When calibrating an instrument, facts to be noted include: * The calibration frequency. * The date of the calibration. * The person who calibrated the instrument. These facts must also be documented in an IAQ log, along with any HVAC system adjustments required to ensure proper air quality levels. An IAQ log, with detailed measurements and facility notes (including the exterior of the building), is helpful for future troubleshooting circumstances and also serves as support material in the defense of legal actions. #### Extreme Care Extreme care must be used when taking IAQ measurements (including the use of the most accurate instrument available). Contaminant levels in commercial buildings are often low in comparison to industrial standards. Usually there is little difference between an acceptable and an unacceptable indoor environment in a commercial building. The error factor of inaccurate test instruments can imply that there is no problem or that a problem exists where none exists. Errors of any kind can have serious health and legal consequences. ### IAQ Test Instrument Calibration **Figure 5-3** shows IAQ Test Instrument Calibration: 1. Connect the airmeter to the gas cannister with hose and calibration cap. 2. Turn the airmeter ON by pressing the button and holding for 3 sec. 3. Enter airmeter CO and CO2 calibration mode. 4. Press the button to start the calibration procedure. 5. Press the button to zero the airmeter. 6. Remove nitrogen when zeroing is complete and press the button. 7. Enter the concentration value (from CO canister) using the button. 8. Press the button to store the entry. ### IAQ Compliant Investigation Procedures #### Instrument Selection Selecting an IAQ test instrument is a process that consists of several steps. One of the main uses of this process is to judge between acceptable and unacceptable conditions of air quality. IAQ test instruments must also have a level of precision high enough to provide acceptable statistical confidence. #### Instrument Accuracy and Precision A test instrument that does not have a high level of accuracy for an application cannot be trusted. * The detection limit of the test instrument should be above or below the precision level required for the application by a factor of at least 10. * The instrument range should be at least twice the level of concern in order to provide statistical confidence in the results. **See Figure 5-4** #### Scientifically Defensible Results Any conclusions drawn from an IAQ measurement must be scientifically defensible. Any conclusions drawn from the data gathered must adequately and truthfully represent the situation. Data correctly derived from test instruments can withstand scrutiny. #### Legal Claims and Counterclaims Legal claims and counterclaims are often based on the IAQ testing process. When selecting an IAQ test instrument, first a list of possible contaminants should be established. Separate reviews for each contaminant should then be set up. IAQ standards are used to develop the level of concern. #### Data Quality Objectives (DQOs) The next step is to define the DQOs. DQOs usually include: * Instrument precision * The method of detection * The detection limit * The representative nature of the samples. **The method detection limit is the minimum concentration of a contaminant that is reported as zero.** #### Representative Nature of Samples The representative nature of samples relates to the degree to which the measurements taken are characteristic of the whole area, medium, exposure, or dose for which the data is used to make decisions. When no regulations are in place for an application, the person doing the testing determines the DQOs. #### Operational Requirements After the DQOs are established, it is necessary to evaluate operational requirements, such as the proper frequency and duration for measurements being taken. Operational requirements are derived from the problem that exists and must be taken at the proper spot in the problem space or area. Other factors that may influence the instrument selection can include the following: * Active or passive instrument operational mode. * Output recording method, including continuous recording, single point in time, or weighted over time. * Report generated, such as electronic signal, computerized data storage, or laboratory report. * Portable or fixed test instrument. * Test instrument power requirements, such as batteries, AC, or mechanical. * Instrument calibration, including frequency, voltage and current generators, particulate generators that follow laboratory procedures or factory recommendations. * Cost of equipment. * Personnel training required for use of instrument. #### Documenting the Selection Process Document the selection process, decisions, and rationale. The specific details to be recorded include: * The objectives. * Levels of concern. * Data quality objectives. * Actual instrument selection. #### Quality Assurance (QA) Plans In addition to documenting instrument selection, it is advisable to include a written quality assurance plan. A written QA plan is a document designed to deliver defensible data acquired using test instruments about indoor air quality. **See Figure 5-5** and **Appendix A** A written QA plan should contain the following: * **Document control** * **Corrective measures** * **The established protocol** developed for each type of air sampling must be followed, especially when more than one person is taking measurements. Measurements taken with different test instruments or under varying methods and conditions can easily lead to false conclusions or interpretations. * **IAQ readings** that fall outside acceptable parameters must be double-checked by recalibrating the test instrument and retesting. #### IAQ Fact Many different handheld meters are on the market to choose from for IAQ contaminant measurements. Most meters have similar functions, but differences do exist between brands. It is essential to follow the manufacturer’s instructions before using a handheld meter. #### Air Properties The basic thermal properties of air must be tested in addition to testing contaminants. Maintaining space temperature and relative humidity is critical to keeping occupants comfortable. **See Figure 5-6** Complaints about excessively warm or cool temperatures should be corrected as soon as possible. Air comfort properties are also important for managing contaminants. Temperature and relative humidity play a vital role in controlling microbial contamination in building spaces. #### Air Comfort Properties **Figure 5-6** shows the measurement of basic air properties, in addition to contaminants, which provide a baseline for the general condition of air quality within a building. #### Temperature and Relative Humidity Temperature measurements are made with a thermometer and relative humidity measurements are made with a slings or fan-operated psychrometer. Humidity measurements can also be performed using a thermohygrometer. Today, thermometers, psychrometers, and hygrometers can be purchased with direct-digital readouts. Digital readout models minimize the need for calculations and using the psychometric chart. #### Thermometer Accuracy Thermometers used for IAQ measurements should have a temperature accuracy of at least ±2°F (approximately ±1°C). A humidity-sensing instrument, such as a psychrometer or hygrometer, should have an accuracy of at least ±2% relative humidity. Laboratories and manufacturing facilities usually require a higher accuracy. #### Digital Humidity Probes Digital humidity probes may be easiest to use because no calculations are needed to derive the relative humidity percentage. In many cases, multifunction test instruments provide carbon dioxide and carbon monoxide sensing as well as temperature and humidity measurements. **See Figure 5-7** #### Indoor and Outdoor Readings Temperature and relative humidity measurements are often taken simultaneously. A good IAQ investigation includes indoor and outdoor measurements of the temperature and relative humidity for purposes of comparison. Taking indoor and outdoor readings provides a clearer picture of the conditions under which the system is operating and the adjustments that are feasible. #### Establishing Baseline Measurement To establish baseline measurements, it is necessary to take daily temperature and relative humidity measurements in representative areas of HVAC zones. The HVAC system must be documented, including: * Occupancy levels * Types of equipment in use. * Type and amount of lighting #### Proper Sensor Placement When testing temperature, personnel should ensure that room sensors are properly located. An HVAC system often responds only to the temperature at the room sensor, so the test instrument probe should be placed within a few inches of the room sensor. #### Preventing Errors When performing temperature or humidity measurements, personnel should not breathe on temperature or relative humidity sensor probes. A stationary engineer should hold the probe so that his or her hands are far from the sensor or probe tip. The radiant heat from hands can cause sensors and probe tips to display incorrect temperature measurements. #### Temperature and Relative Humidity Readings Temperature and relative humidity readings should be taken at several locations and heights within an occupied space. Temperature measurements should be even throughout the space. Wide variations in temperature could indicate inadequate air circulation within the space or the presence of radiant heat from windows or equipment. The vertical temperature difference, from floor to ceiling, should not exceed 5°F within an occupied space. #### IAQ Fact The occupied zone is defined by ASHRAE Standard 62.1-2004, Ventilation for Acceptable Indoor Air Quality, as “the region within an occupied space between planes 3” to 72” (75 mm to 1800 mm) above the floor and more than 2' (600 mm) from any walls or fixed air-conditioning equipment.” #### Temperature Measurements Temperature measurements that vary widely suggest balance or control problems with the HVAC system. #### Mold and IAQ Issues Measurements are also taken in specific areas where mold or IAQ issues are more likely to be present. Cabinet doors and decorative furnishings can block airflow to small spaces, causing humidity to increase over the recommended value and contributing to mold growth. #### Air Volume Measurement An air volume measurement is taken to confirm that airflow out of each diffuser and register in a building meets design specifications. Comparisons can be made with a schematic duct system layout print or an outlet air balance report from the most recent written test and balance report. #### Testing Air Volume with Anemometer * Anemometers or air-capture hoods are used to measure the volume of air moving (flow rate) in cubic feet per minute (cfm). * An anemometer is a device that measures average air velocity or average airflow rate. An anemometer is placed at the opening of a diffuser and operated according to the manufacturer's instructions. **See Figure 5-8**. * The manufacturer’s specifications indicate the recommended number of readings and the location where measurements should be taken. #### Velocity Measurements Velocity measurements are averaged and then multiplied by the K factor for the specific type of diffuser in use. The K factor is a number that represents the actual open area and design characteristics of a specific diffuser. The result of the K factor equation is the flow rate, in cubic feet per minute (cfm), out of the diffuser. #### Anemometer vs. Flow Hood * A flow hood is a test instrument that is placed over a diffuser to measure the volume of air moving in cubic feet per minute. **See Figure 5-9**. * Flow hoods are easier to use than anemometers because they provide a direct reading without the need for calculations. * Flow hoods also save a considerable amount of time when performing field measurements. ### Air Circulation Air must be allowed to circulate completely through an occupied zone. Air is needed to flush contaminants from occupied and unoccupied spaces, which cannot happen when air is blocked from reaching certain locations. The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) sets the maximum air velocity in a building at 50 feet per minute (fpm) in the summer and 30 fpm in the winter. Higher air velocities may cause drafts. Anemometers or velometers with a range of 5 fpm to 100 fpm are appropriate tools for taking air velocity measurements. A velometer is a device that measures the velocity of air flowing out of a register. ### Chemical Smoke Test A chemical smoke test is an IAQ test that shows the airflow inside a space or from one space into another space. Chemical smoke flows with the smallest of air currents because chemical smoke is heatless. **See Figure 5-10** #### Flow Pattern Chemical smoke flows from high-pressure spaces to low-pressure spaces. * Smoke flowing from a space, such as under a door or through window seals, shows that the space is under positive pressure. * Smoke flowing back into a space, such as away from a door or window, shows that the space is under negative pressure. * Smoke released at the shell of a building (by doors or windows) indicates that HVAC systems are maintaining interior spaces under positive pressure relative to the outdoors. ### Handheld Meter Testing for Contaminants The presence of contaminants as part of the inside air of a building does not mean that occupants will experience harmful health effects. The duration, amount of exposure, and the type of contaminant determine the health effects felt by building occupants. #### Contaminant Testing Using Handheld Meters Some contaminants may be easily tested using handheld meters. Handheld meters are often used to test nitrogen dioxide, carbon monoxide, carbon dioxide, and ozone. #### Nitrogen Dioxide In the past, outside experts conducted real-time sampling for nitrogen dioxide. When elevated nitrogen dioxide (NO2) concentrations are present, there are also elevated carbon monoxide (CO) concentrations. Therefore, stationary engineers would perform CO samplings to get a sense of NO2 levels. Solving a CO problem generally solved any NO2 problem. Today, portable nitrogen dioxide monitors are available with the required level of accuracy. #### Permissible Levels of Nitrogen Dioxide * No standards have been agreed upon for permissible levels of nitrogen dioxide in indoor air. * ASHRAE and the U.S. Environmental Protection Agency National Ambient Air Quality Standards (NAAQS) list 0.25 parts per million (ppm) to 1.0 ppm for an hourly average limit and 0.053 ppm as the average 24 hr limit for NO2 in indoor air. **See Figure 5-11** ### Nitrogen Dioxide Exposure Limits **Figure 5-11** shows nitrogen dioxide exposure limits: | Classification | 10 Minutes* | 30 Minutes* | 1 Hour* | 4 Hours* | 8 Hours* | |---|---|---|---|---|---| | Nondisabling | 0.50 | 0.50 | 0.50 | 8.2 | 6.7 | | Disabling | 20 | 15 | 12 | 0.50 | 0.50 | #### Exposure Symptoms | Exposure | Symptoms | Prevention | First Aid Treatment | |---|---|---|---| | Inhalation | Burning sensation, cough, headache, dizziness, sore throat, nausea, and vomiting | Ventilation-area exhaust Respiratory protection-supplied air | Half-upright position with rest and fresh air; artificial respiration may be required. | | Skin | Burns, redness, and pain | Protective clothing and neoprene gloves | Rinse with water for 15 min; remove clothes (discard); rinse again for 15 min | | Eyes | Severe burns, redness, and pain | Nonvented eye protection or face shield | Rinse eyes with water for 15 min | | Ingestion | - | Do not drink or eat in nitrogen dioxide environment | Rinse mouth for 15 min | * in ppm Sources: Occupational Safety & Health Administration (OSHA), U.S. Department of Health and Human Services-Food and Drug Administration (FDA), and Praxair, Inc. #### Nitrogen Dioxide Monitor Usage A nitrogen dioxide monitor is a meter that measures the amount (in parts per million) of nitrogen dioxide in an air sample. Measurement of the concentration of NO₂ in an air sample is based on a chemical reaction between ozone(O₃) and nitrogen monoxide (NO), which produces light at a certain wavelength. The intensity of the light energy is proportional to the concentration of nitrogen monoxide and is measured by a photodetector. #### Nitrogen Dioxide Monitor Operations Inside a nitrogen dioxide monitor, sampled air is drawn through two separate paths. * In one path, the air is mixed directly with ozone, and the resulting light energy is measured to determine the concentration of nitrogen monoxide (NO) in the air. * In a separate path, sampled air is sent first through a catalytic reduction surface, which converts the NO₂ to NO. * The sample is then mixed with ozone to create light energy, which is measured with the photodetector. This measurement represents the combined concentrations of NO and NO₂ in the original air sample. * The difference between the two measurements is the level of NO₂ alone in the original air sample. #### Nitrogen Dioxide Measurement Procedures **Figure 5-12** shows nitrogen dioxide measurement procedures: 1. Set up the nitrogen dioxide monitor. 2. Synchronize the software between PPC and PC. 3. Turn the nitrogen dioxide monitor on. 4. Calibrate the probe. 5. Tap the View key on the display screen to view continuous nitrogen dioxide measurements. 6. Tap the Stop key on the display screen to stop nitrogen dioxide measurements. 7. Tap the Stop key again to turn off the nitrogen dioxide monitor. #### IAQ Fact Many types of contaminants can be measured by a handheld meter designed for that specific contaminant only. However, some handheld meters can measure several contaminants simultaneously. #### Carbon Monoxide Carbon monoxide (CO) can be measured by direct-reading instruments or detector tubes. Measuring more than one sample per location improves the accuracy of the results. Direct-reading instruments or detector tube measurements should be in the range of 1 ppm to 50 ppm. **See Figure 5-13** #### Accuracy of Detector Tubes The accuracy of detector tubes is ± 25%, at a minimum. Detector tubes take spot samples. They're sufficiently accurate for screening samples. It's important to follow the manufacturer’s directions when using detector tubes. Detector tubes are relatively inexpensive, and replacement tubes can be purchased as necessary ### Carbon Monoxide Exposure Limits **Figure 5-13** shows carbon monoxide exposure limits: | Classification | 10 Minutes* | 30 Minutes* | 1 Hour* | 4 Hours* | 8 Hours* | |---|---|---|---|---|---| | Nondisabling | 2500 | 1500 | 600 | 150 | 30-50 | | Disabling | 6000 | 3000 | 800 | 400 | 80 | #### Exposure Symptoms | Exposure | Symptoms | Prevention | First Aid Treatment | |---|---|---|---| | Inhalation | Asphyxiation | Ventilation-area exhaust Respiratory protection-supplied air | Artificial respiration and cardiopulmonary resuscitation | | Skin | Possible frostbite | Appropriate gloves-not rubber or neoprene | Rinse with warm water | | Eyes | Mechanical injury | Nonvented eye protection or face shield | Force eyes open and rinse with lukewarm water | | Ingestion | - | - | - | * in ppm Sources: Occupational Safety & Health Administration (OSHA), Spectra Gases, Inc., Washington State Department of Labor and Industries, and International Program on Chemical Safety (IPCS) #### Carbon Monoxide Meter Usage A carbon monoxide meter measures the amount (in parts per million) of carbon monoxide in an air sample. A carbon monoxide meter indicates that CO is present by displaying the amount on an LCD display and by using an alarm. The alarm is usually activated at a preprogrammed value of 35 ppm, but can be reprogrammed for any alarm value. Many CO meters indicate any amount displayed above 1000 ppm as OL (over measured limit). #### Carbon Monoxide Meter Operation CO is measured based on how it absorbs infrared radiation. An air sample is drawn into a chamber and exposed to a beam of infrared radiation. A decrease in the intensity of infrared radiation is proportional to the concentration of CO in the air sample. This is measured by a special detector. A duplicate beam passes through a reference chamber with no CO present. The difference between the two measurements corresponds to the measurement of CO concentration in the air sample. #### Carbon Monoxide Measurement Procedures **Figure 5-14** shows carbon monoxide measurement procedures: 1. Turn the carbon monoxide meter on. It performs a self-test, establishes a baseline for comparing the CO concentration of the testing environment, and then immediately starts taking CO measurements. 2. The meter establishes a new baseline before beginning continuous measurements. 3. The carbon monoxide meter displays CO measurements on its display. 4. It may also beep to indicate a new maximum level. 5. Move the meter to other locations to determine the area with the highest concentration. #### Carbon Dioxide Normal outdoor air concentrations of carbon dioxide (CO₂) range from 300 ppm to 350 ppm. Indoor carbon dioxide concentrations are slightly higher because people exhale carbon dioxide into indoor air space. During the workday, CO₂ levels peak before lunch and again late in the afternoon before people leave for home. #### Measurements of CO₂ Peak Levels Measurements of CO₂ peak levels are an indirect measurement of the amount of outdoor air being brought into a work area. According to ASHRAE Standard 62-2007, the upper indoor limit for CO₂ is 1000 ppm. **See Figure 5-15** #### Elevated CO₂ Levels CO₂ levels that exceed 1000 ppm indicate inadequate supply or distribution of outdoor air for the level of occupancy in a space. Elevated CO₂ levels are associated with occupant complaints. Occupant complaints can occur at levels below 1000 ppm, particularly if there is a contaminant source that has not been controlled or the occupant space does not have local exhaust ventilation. #### Corrective Actions To prevent problems, corrective action must be taken anytime levels of CO₂ reach or exceed 800 ppm. Outdoor concentrations above 400 ppm may indicate an outdoor contaminant problem, such as vehicle exhaust or combustion sources. Monitoring outdoor CO₂ levels provides an indication of the quality of air being brought into a facility. #### Concentrations of CO₂ Concentrations of CO₂ are also a good indicator of the concentrations of other contaminants. If CO₂ levels are high, it is likely that there are other IAQ problems. This makes it possible to appropriately suspect other contaminants even if the stationary engineer does not have meters to test for them. #### IAQ Fact Elevated levels of carbon dioxide are remediated by introducing more outdoor air into the building. If there are any other contaminants in the indoor air, increasing ventilation will likely also help lower their concentrations. ### Carbon Dioxide Exposure Limits **Figure 5-15** shows carbon dioxide exposure limits: | Classification | 10 Minutes* | 30 Minutes* | 1 Hour* | 4 Hours* | 8 Hours* | |---|---|---|---|---|---| | Nondisabling | 15,000 | 10,000 | 7500 | 6000 | 5000 | | Disabling | 30,000 | 20,000 | 15,000 | 10,000 | 10,000 | #### Exposure Symptoms | Exposure | Symptoms | Prevention | First Aid Treatment | |---|---|---|---| | Inhalation | Asphyxiation-headaches and drowsiness | Ventilation-area exhaust Respiratory protection-supplied air | Artificial respiration using oxygen | | Skin | Possible frostbite | Cuffless trousers-no rubber or neoprene gloves | Do not remove clothing-rinse with warm water | | Eyes | Stinging | Face shield | Force eyes open and rinse with lukewarm water | | Ingestion | - | - | - | * in ppm Sources: Occupational Safety & Health Administration (OSHA), Praxair, Inc., and Valero Marketing & Supply Company #### Preferred Measuring Devices The preferred measuring devices for CO₂ are direct-reading instruments that use infrared or electrochemical detection. The allowable instrument measurement range should be from 200 ppm to 2000 ppm, with an accuracy of ± 10% at 1000 ppm. Most direct-reading detector manufacturers bundle the CO₂ detector along with temperature and humidity measurements. Multifunction measuring devices often come with a data logger and software to store measurements and have the capability to retrieve the measurements later from a computer file. #### Detector Tubes Detector tubes can also be used, although detector tubes are less accurate. Detector tubes are also affected by hot or cold weather, which makes them less useful for outdoor measurement comparisons. #### Baseline Measurements Baseline measurements are taken from multiple samples in representative spaces of each HVAC zone. Outdoor samples must also be taken, specifically near the outdoor air intake. During each sampling period, personnel should record the air damper settings, relative occupancy, and weather conditions. Initially, it is recommended to take monthly measurements in representative areas of each HVAC zone. #### Carbon Dioxide Meter Usage A carbon dioxide meter measures the amount (in parts per million) of carbon dioxide in an air sample. A carbon dioxide meter indicates that carbon dioxide is present by displaying the amount of carbon dioxide on an LCD display. Carbon dioxide measurement is a common feature of multifunction meters, often combined with temperature, relative humidity, and carbon monoxide measurement functions. #### Measurement of Carbon Dioxide Concentrations Similar to carbon monoxide, carbon dioxide concentration is measured by its absorption of infrared radiation. It absorbs radiation at a slightly different wavelength, however, so with the proper filters and electronics, the concentrations of the two gases can be distinguished from each other. The similar methods of detection explain why concentrations of both gases can be measured by many multifunction meters. #### Carbon Dioxide Measurement Procedures **Figure 5-16** shows carbon dioxide measurement procedures which are similar to carbon monoxide measurement procedures: 1. Turn the carbon dioxide meter on. It performs a self-test and displays the meter’s battery charge, date, last calibration date, and absolute barometric pressure. **See Figure 5-16** 2. When taking measurements, the sensor should be held perpendicular to the airstream being measured. 3. The measured CO² concentration appears on the meter’s display. 4. The display can be toggled to show the maximum, minimum, and/or average CO₂ values. #### Stationary Engineer Responsibilities Stationary engineers should test and record carbon dioxide for multiple room locations by moving around the area with the meter. Each measurement should be carefully recorded in the IAQ testing log. Carbon dioxide should also be tested in various points in an HVAC system, including outside-air intakes, return-air grills, and mixed-air plenums. #### Carbon Dioxide Meters Capabilities Some meters allow the user to store these measurements and to use them to automatically calculate the percentage of outdoor air used to ventilate the system. ### Ozone According to the EPA, the permissible ozone (O₃) level for interior building spaces is 0.08 ppm. **See Figure 5-17** Testing for ozone levels is conducted by outside experts in many facilities because the precision analyzers can be expensive and require extensive calibration. These analyzers are based on the measurement of ultraviolet absorption to determine ozone concentrations. #### Portable Ozone Meters However, manufacturers have developed less expensive, portable ozone meters that can be used by stationary engineers. These meters use a measurement principle based on semiconductors and is not as accurate as the precision analyzers, but this measurement principle provides a useful estimate of the ozone levels. If these ozone meters detect an elevated concentration of ozone, further investigation can be conducted by outside experts with more sophisticated instruments. #### Dry Colormetric Ozone Sensors Also, dry colormetric ozone sensors (detector cards) are readily available and affordable for the constant monitoring of personnel in potential ozone-contaminated environments. These cards are worn as badges and change color to indicate approximate ozone exposure. #### Ozone Meter Usage An ozone meter measures the amount (in parts per million) of ozone in an air sample. An ozone meter indicates the ozone concentration on a multicolored bar graph or LCD display. Occupied space ozone meters usually have an accuracy range of 0.02 ppm to 0.14 ppm, or 0.0 ppm to 10 ppm. ### Ozone Measurement Procedures **Figure 5-18** shows ozone measurement procedures: 1. Turn the carbon dioxide meter on. 2. Hold the carbon dioxide meter perpendicular to the airstream. 3. Press the CO2 button to start taking carbon dioxide measurement. 4. The meter displays CO2 measurements. To show minimum, maximum, or average values, toggle the Min/Max button. 5. Record the carbon dioxide values. 6. Move to other test locations to take measurements. 7. Test for the percentage of outdoor air - CO2 8. Turn the carbon dioxide meter off. ### Ozone Exposure Limits **figure 5-17** shows ozone exposure limits: | Classification | 10 Minutes* | 30 Minutes* | 1 Hour* | 4 Hours* | 8 Hours* | |---|---|---|---|---|---| | Nondisabling | 0.3 | 0.2 | 0.12 | 0.11 | 0.1 | | Disabling | 25 | 10 | 2 | 1 | 0.5 | #### Exposure Symptoms | Exposure | Symptoms | Prevention | First Aid Treatment | |---|---|---|---| |