Category Archives: Indoor Air Quality (IAQ) Testing Dallas – Fort Worth – Austin – Houston

EMF Testing Indoor Air Quality Radon Gas Testing: 214.912.4691 Dallas – Houston – Austin – Fort Worth

Powerline Home Safe Distance Cell Phone RF Surveys

Cell Tower Site on High Voltage Power Line near homes in residential area in North Dallas – EMF Testing and Surveys

EMF Testing / Magnetic Field Survey & Safe Distance Measurement Services

EMF testing for those concerned about living near powerlines and feeders is available for commercial clients and limited residential with reports that range from verbal to complete reports with photo documentation and graphics. We also provide consultation on viable strategies and products for EMF protection. We travel all over Texas and cities in adjacent states including Dallas, Houston, Fort Worth, Austin, San Antonio and Oklahoma City.

RF (Radio Frequency) Scans and Evaluations – Maximum Permissible Exposure (MPE)

We test RF energy for frequency and amplitude in order to find sources and evaluate safety with respect to FCC regulatory, compliance and precautionary guidelines, and to determine potential interference issues between wireless routers, cell phone repeaters / boosters, Radio Frequency Identification (RFID) systems, and wireless microphone / audio / video data systems.

Magnetic / Electric / RF & EMF Shielding Consultations including proper grounding

If you have an issue with electromagnetic energy that is either a safety issue or causes equipment interference, we are fully qualified to assess, troubleshoot and make sound recommendations to fix or mitigate the situation.

Radon Gas Measurements & Surveys (Short / Long Term Testing)

With a background in radon and radiation safety, we are capable of evaluating and reporting on radon gas levels, how they compare with EPA standards and whether a mitigation solution is called for.

EMF Testing for Electrical Wiring Issues Indicated by Excessive EMF Fields

Whether you believe in the safety hazards of EMF or not, the most common source of high EMF fields inside the home is improper wiring which fails to conform to current NEC code. ScanTech can detect and direct repairs on electrical wiring that manifests as an abnormal magnetic field.

Preliminary Construction Surveys / Property Transfer Phase I Environmental Site Due Diligence Survey testing regarding Indoor Air Quality (IAQ) – EMF Consultation for Safety and potential EMI – Radon Testing for Multi-Family Dwellings and Commercial Buildings.

We are often called out to site before a structure or complex is erected in order to survey and communicate any possible issues and the potential impact of nearby power lines, substations, transformers, cell towers and other EMF/RF generating sources. We also make construction recommendations for minimizing electromagnetic field emissions for safety and electromagnetic Interference concerns with sensitive manufacturing and research equipment.

Indoor air quality testing for VOC levels regarding Certificate of Occupancy permits according to City of Dallas Green Ordinances. Also known as the 804.2 Post-Construction, Pre-Occupancy Baseline IAQ Testing which is a 4 hour test for 500 uG / m^3 or less of VOCs.

Magnetized & Radiation Contaminated Metals, Stone and Imported Products

ScanTech has been in the radiation survey business for over 10 years and is routinely called upon to investigate cases of suspected radioactive contamination and magnetized ferrous metals which can cause unusual issues. Our instrumentation includes several Geiger counters with capable of detecting Alpha and Beta particle emissions, X-Rays and includes specialized Gamma radiation scintillation detectors.

Weak Cell Phone Signal Reception Issues & Wireless LAN Problems / RFID Interference

Weak Cellular Phone (including 2G / 3G / 4G LTE) & Wireless Strength Measurements with consulting for correction / mitigation in commercial buildings, residential and multifamily properties with poor coverage, slow data rates and dropped calls for all major telecom and communications carriers including Sprint, T-Mobile, Verizon, AT&T for smartphones, tablets, iPads, etc. Radio Frequency Identification system troubleshooting and interference issues investigated. We also perform FCC RF Compliance surveys for MPE (Maximum Permissible Exposure) including rooftop antenna installations.

Implanted Biomedical Device EMF / EMI Measurement Compliance Surveys and Testing for Patient Safety

Medical Device Compliance Testing (Pacemakers, Implantable Defibrillators, ICD’s etc. – Medtronics, St. Jude Medical, Boston Scientific, Mortara) for individuals returning to work or home after implant surgery to identify potential hazards from AC/DC Magnetic and Electric Fields, Microwaves, RF and general EMI (Electromagnetic Interference).

Hospital Infant Anti-Abduction Security Systems

ScanTech troubleshoots RFID integrated systems designed to protect neonatal care facilities that employ systems such as Hugs by Stanley Healthcare and MyChild by McRoberts Security Technologies.

Electrostatic Discharge (ESD) Testing, Consulting And Evaluation for Commercial, Industrial and Biomedical Companies / Applications / Clients

We have the equipment to determine the sheet resistance of ESD flooring material and if anti-static grounding is working as well as the ability to identify troublesome materials and processes which can cause equipment malfunction and electric shock / fire / explosion hazards. We can also measure relative air ion counts, humidity and the direct DC static voltage on surfaces (positive or negative) up to 30,000 V to determine which objects in the environment may be damaging your static sensitive equipment.

Indoor Air Quality (IAQ) Surveys to Determine Relative Air Cleanliness PM2.5 / PM10 / HEPA Filtration Efficiency / Formaldehyde / VOC / CO2 (Carbon Dioxide) / O2 Oxygen % Concentration & Contamination for Commercial Building and Industrial / Occupational Atmosphere Evaluations with expertise in Nanotoxicology and Medical Environmental Illness Testing

We have time based datalogging air laser analysis available to characterize particulate matter such as small particle contaminants (down to 0.5 microns such as bacteria) and large particle counts (2.5 um and larger) for potential pollen, dust and mold detection which are also known as RSPs. (Respirable Suspended Particles) We can also check for formaldehyde concentrations and VOCs (Volatile Organic Compounds) levels from outgassing materials such as pressed wood flooring or glues and other binders.

Elevated CO2 (carbon dioxide) levels are indicative of Sick Building Syndrome and poor air exchange characteristics in a structure.

New nanomaterials on the market have raised concerns about the potential toxic effects of nanoparticles (such as carbon nanotubes, titanium dioxide, silver NPs, etc.) in particulate, aerosol, aqueous forms and their in-vivo effects.

Commercial, industrial, occupational health and limited residential applications.

OSHA Sound / Noise Level Surveys for Safety Audits

Sound (Commercial) & Industrial Safety field surveys and measurement including for acoustic OSHA sound and STC (Sound Transmission Class) noise levels / ordinances / testing (meeting ANSI & IEC Type 2 standards) to determine compliance and evaluate potential issues with excessive or disruptive noise.

Photometric Glare & Illumination (Lighting Level) Surveys for Safety, OSHA and City Ordinance Compliance

Photometric mapping to identify poor / insufficient / excessive illumination, security camera glare, ATM lighting security assessments, ADA lighting requirements / compliance, and privacy. Many cities have enacted ordinances which limit the amount of light emanating at the property line at night in foot candles. (fc) We can also measure lighting flicker rates which can cause headaches and other performance issues as well as evaluate possible disruption of circadian rhythms which lead to insomnia and lack of restful REM sleep.

Metallurgical Analysis & Consulting

Materials analysis for ferrous / non-ferrous metals / alloys. Tools and tool steel quality evaluations for carbon content. Also magnetic / RF / electric shielding capability, corrosion resistance, heat resistance, degree of temper, quench methods, elasticity, weathering, and electrical quality consulting. Metamaterial composite research for nanotechnology, biomedical, and exotic applications. (graphene, nanoparticles, carbon nanotubes, nanodiamond, etc.) Radioactivity testing for scrap metal or other suspected products.

Formaldehyde: Indoor Air Quality Pollutant and Testing


Formaldehyde Testing Dallas – Fort Worth

ScanTech offers selective testing of indoor formaldehyde testing in both residential and commercial buildings in the Dallas – Ft. Worth region.

Formaldehyde (Chemical formula CH2O and also known as Methanal) is a colorless, water soluble gas at room temperature with a pungent, irritating odor at less than 1 part per million. (1 ppm – and detectable as low as 0.83 ppm) It is an inexpensive chemical with excellent bonding properties produced in high volume throughout the world. A major use is in the fabrication of urea-formaldehyde (UF) resins used primarily as adhesives when making plywood, particleboard and fiberboard. In the 1970’s it was a component of UF foam insulation in sidewalls until it was banned in 1982 by the U.S. Consumer Product Safety Commission because they found levels as high as 4 ppm. (but the ban was later overturned)

Due to it’s very low boiling point of -19 Celsius, formaldehyde is technically a VVOC (Very Volatile Organic Compound) and has very strong chemical and photo-chemical reactivity. It is commercially available as formalin which contains 38% formaldehyde and 6% – 15 % methanol.

Many common household cleaning agents contain formaldehyde and other sources include cigarette smoke and the combustion byproducts of gas / wood stoves and unvented space heaters such as kerosene heaters. It can also be found in paper products such as facial tissues, paper towels and grocery bags.

In general, emission or outgassing rates of formaldehyde increase with temperature, humidity, wood moisture content and decreased formaldehyde in the air. (due to passive diffusion) Generally, some remediation can be found by decreasing humidity and temperature, sealing materials with vinyl wallpaper or non-permeable paint and increasing ventilation. (air exchange rates)

Plywood is composed of several thin sheets of wood glued together with UF copolymeric resin which originally had a high HCHO to urea ratio of 1.5 to 1 to ensure adequate chemical cross-linking of all primary and secondary amino groups. Because the excess HCHO outgasses significantly and subsequently caused health complaints, this ratio was reduced to 1.05 to 1. Particleboard (compressed wood shavings mixed with UF resins at high temperatures) can emit formaldehyde continuously for comparatively long times; from several months to several years. Medium density fiberboard (MDF) was found to be the highest emitter of formaldehyde. Elevated levels are more likely to be found in newer homes with pressed wood materials such as flooring lumber mixed with the UF resin.

UF wood adhesives have excellent bonding performance, but are somewhat chemically unstable and release monomeric formaldehyde due to hydrolysis of the methyol end groups and sometimes the methylene bridges themselves. This means that hydrolytic decomposition and outgassing of HCHO is dependent on moisture levels, so UF-bonded wood products are primarily for indoor use where humidity levels are typically controlled.

Emissions do tend to decrease with time as the materials out-gas, age and cure. It is also used in the production of urea-formaldehyde foam insulation. (UFFI)

While there are several other sources of formaldehyde such as wood and forest fires, cigarette smoke, motor vehicle combustion, and decomposition of methane by sunlight and oxygen, etc. indoor levels are generally higher than outdoor levels. (10 – 20 parts per billion or 0.010 ppm – 0.020 ppm but may reach levels of 50 ppb in areas with significant photochemistry / smog )

Formaldehyde Molecule

Formaldehyde Molecule

Formaldehyde is also produced in the human body in small amounts as it is a metabolic byproduct of drinking alcohol (ethanol) among other chemical pathways. But the amount is relatively small and rapidly broken down into formic acid.

Individual sensitivity to formaldehyde varies, but from 10 – 20 % of the population appears to be highly sensitive to relatively low concentrations. This may be a result of TVOC (Total Volatile Organic Compound) synergy with other pollutants. The principle symptoms experienced are irritation of the eyes, nose, throat, dry facial skin and asthma like symptoms. (difficulty breathing, constriction of the bronchial tubes) Higher concentrations may even lead to headaches, fatigue, insomnia, nausea, unnatural thirst, menstrual irregularities, epistaxis, (nosebleed) coughing, chest / abdominal pain, and rapid heartbeat. (tachycardia)

Allergic dermatitis may occur from skin contact. There are also neurological-like symptoms in some, (including depression) with the chance of potential sensitization and even upper respiratory system cancers. There is some controversy about the cancer causing / carcinogenic effects with some evidence showing that risk only substantially increases at very high exposure levels such as in occupations which deal directly with formaldehyde such as embalmers and anatomists. But formaldehyde has been shown to be genotoxic in cell cultures which causes damage through DNA cross-linking, single strand breaks and chromosome aberrations which indicate that HCHO is mutagenic as well.

Regardless in testing, levels as low as 0.25 ppm (which is below the detectable odor threshold) significant eye and throat discomfort increases in frequency. Chronic bronchitis and asthma are more prevalent in children in homes with HCHO levels in the 0.06 – 0.12 ppm with a 22% decrement between the two values.

Testing Particulate Matter and Indoor Air Quality (IAQ)

Respirable Suspended Particles (RSP) are particles or fibers in the air that are small enough to be inhaled. Particles can exist in a number of states including solids, liquids, a combination of the two. Particulate matter that is either inherently organic life (such as viruses or bacteria) or are given off by biological life (such as mold spores, pieces of fungi, pollen, plant fibers, etc.) are what is known as bioaerosols.

There is another class of compounds which are chemicals released by biological organisms known as Microbial Volatile Organic Compounds or MVOCs. These are typically low molecular weight chemicals which have a high vapor pressure so they tend to remain in the air long enough to be detected and/or breathed in. Often they are responsible for odors that result from bacterial / toxic black mold growth or other primary/secondary metabolic byproducts of microorganisms.

In general, particles of 10 um (microns) or greater in diameter will tend to get caught in the mucous membranes of the nose before they have a chance to settle in the lungs. But particles between 2.5 um and 10 um (known as PM10 which is short for Particulate Matter 10 um) can migrate to tissues of the upper respiratory tract where they can cause health issues depending on the nature and the concentration of the contamination. Particles smaller than 2.5 um (known as PM2.5) can actually penetrate the alveoli, or small air sacs of the lungs and enter the blood stream.

The particle counter used by ScanTech measures both small (0.5 – 2.5 um) and large (2.5 – 10 um) particles to warn of potential hazards in the air you breathe.

Particle Size Penetration Respiratory System

The smaller the particles, the deeper they penetrate into the respiratory system


Radon Gas Testing in Dallas / Fort Worth and Texas: More Critical For Home Safety Than You Think

Radon Gas Home Inspections in Dallas Texas    Radon Gas A Home Danger in Dallas

20,000+ Lung Cancer Deaths Annually in the United States

I had another radon gas inspection job in Garland recently and a remark by one of the interested parties got me to thinking. This was relayed by a third party, but I believe the statement was something along the lines of: “Texas homes do not have a radon problem” which I know to be patently false as I have found homes that tested beyond the EPA action limit of 4 picoCuries/liter including MINE. (I have measured 4.9 – 8.0 pCi/L in the Lake Highlands area which is equal to a pack of cigarettes a day) I have also personally been to several residences that had radon mitigation systems in place, and when they were turned off, the levels went back into the danger zone.

So how do myths and misinformation like this get perpetuated? Radon is a more common issue in other parts of the United States and tends to be more detectable in homes with basements, (as radon is heavier than air) but it is common enough in the North Texas region to be worth checking as a part of indoor air quality testing in Dallas and Fort Worth.

The number of homes in the Dallas, Tarrant, Collin and Denton counties exceed the EPA action limit 5 – 10 % of the time which IS statistically significant; up to 1 out of 10 homes. Furthermore if you add in the number of homes which are marginal (2.0 – 3.9 picoCuries/Liter) as radon gas concentrations vary throughout the day, year, etc. then the number of potentially affected homes in North Texas is closer to 16 – 24 %.

Also, the World Health Organization (WHO) recommends a lower limit than the EPA with the mitigation safety limit set at 2.7 pCi/L versus the higher limit of 4.0 pCi/L by the Environmental Protection Agency. And there is NO SAFE LIMIT of radon gas, any amount is bad, but you can’t get away from it entirely as even outdoor levels are typically 0.3 pCi/L and average indoor is 1.1 – 1.3 pCi/L.

So how dangerous is radon gas? Here is a quick risk comparison by the EPA:

Radon Gas Risk Statistics

Radon Gas Risk Statistics

This graph shows only 15,000 deaths annually, (the lower number is because the stats are derived from 1986 data quoted by Environmental Science Technology Vol 24 pp. 774 – 1990)  but a more recent EPA report (2014) shows closer to an estimated 20,000+ lung cancer deaths annually due to radon – 2nd only to smoking in direct cause – which is actually higher than the fatalities caused by drunk driving in which a great deal of energy has been focused on in recent years.

The problem with radon gas is that it is invisible, silent, and much harder to track than the erratic, weaving driving patterns of an inebriated driver. Couple this with a mythologies like: “Texas homes don’t have radon” or “You need to have a basement for radon to be an issue” and this becomes a significantly overlooked risk and safety factor that is relatively easy to test for and not necessarily that expensive to correct.

How does radon gas do it’s damage? By the emission of inhaled alpha particles that get into the lungs and whose ionizing radiation damages cell DNA. This mechanism works by attacking DNA molecules within the cells to form free radical ions, or changes the molecules themselves into excited molecules that can form biochemical pathways to cancer.

Radon Gas Inhaled Lung Damage Alpha Radiation

Radon Lung Damage Alpha Radiation

So even if your home has no basement (very few residences in Texas do) then why be concerned? Because the gas can still seep in through cracks in the foundation or gaps in a pier and beam construction. (you don’t need a basement to have a radon issue)

Radon Gas Home Inspection in Dallas / Ft. Worth to find potentially unsafe levels of radioactivity due to these various sources of entry

Radon Gas Home Inspection in Dallas / Ft. Worth to find potentially unsafe levels of radioactivity due to these various sources of entry

The solution is to first retest to make sure that the radon levels are consistently high enough to warrant attention and if so, proper ventilation is designed and installed by a professional radon mitigator, and then the residence retested to make sure that the system is working. Incidentally, ScanTech does no mitigation as we consider it a potential conflict of interest.

But for a prospective homeowner who is interested in a property, it is important to get the radon checked as soon as possible once you are inside the option period. The reason why is because of the time delays in deploying the kits, waiting the 48 – 96 hours for the kits to develop, transit time to the lab and the radon lab processing / reporting time. This means a dead minimum of 4 days under IDEAL circumstances with rush fees and hand trucking the kits in to the lab. Otherwise, it can take up to over a week which can easily exceed the standard 10 day option period.

ScanTech does have the ability to check the radon levels with a special digital tester that can get results much more quickly (in as little as 1 – 2 days after deployment) with the same level of accuracy as the activated charcoal radon test kits described above and it is less expensive when comparing a return trip to retrieve the device and interpret the results versus a return trip for the charcoal kits.

The charcoal kit route is more feasible if the testing is not as time sensitive and/or the client is willing to either mail or hand carry the kits into the radon testing lab itself located in Dallas County.


RADON FAQ PAGE for Dallas / Fort Worth & Surrounding Counties

Counties & Cities Served by ScanTech Technical Consulting

Service Cities for EMF – Indoor Air Quality Testing Smart Meter – RF (Radio Frequency) inspection services include: Plano, Highland Park, University Park, Park Cities, Arlington, Fort Worth, Grapevine, Frisco, Denton, McKinney, Allen, Lewisville, Irving, Mesquite, Bedford, Euless, Richardson, Coppell, Grand Prairie, Garland, Addison, Farmers Branch, Rockwall, Carrollton, Parker, Rowlett, Lucas, Fairview, Park Cities, Keller, Roanoke, The Colony, Highland Village, Lake Dallas, Corinth, Prosper, Austin, Houston, Round Rock, Spring, The Woodlands, Bastrop, Duncanville, Lancaster, Rowlett, Royse City, Trophy Club, Southlake and Hurst. Counties served include Dallas, Collin, Denton, Tarrant, Travis, Harris and Rockwall County.

ScanTech EMF & Radon Service Area

ScanTech Dallas – Fort Worth EMF, Indoor Air Quality & Radon Testing Service Areas

EMF Safety Levels in Homes and Residences – A Commentary

I had a question recently after performing a survey where my prognosis was essentially: “There is no reason for excessive concern regarding EMF fields with respect to this property.”

This seemed like a sufficiently concise response, and yet I got a response back that was along the lines of this:

“You didn’t mention any range of values like highest and lowest safest values in your report. Can you please let us know the range.”

A very good question and this was my response:

The reason I did not put a range is because there is no such thing as a hard, rigid number as to what is safe or unsafe because there are so many factors involved.

If I told you that 3 milliGauss (mG) is the safe limit, that implies that 2.97 mG is perfectly fine and 3.04 mG is dangerous which would not be a true statement.

While I believe EMF fields have an effect on the human body, it is fairly weak in typical fields found in everyday life because the human body compensates for a variety of conditions in a  continuous process called homeostasis. Also by focusing too much on the magnetic fields you will have a tendency to overlook more established and dangerous conditions such as radon gas, poor indoor air quality, antibiotic resistant bacteria, mold, mosquito and tick borne viruses and diseases, etc.

EMF fields do not behave like chemicals which have fairly well established dosages and exposure levels set by government agencies and scientists such as LD50 (Lethal Dose 50 %) or STEL. (Short Term Exposure Level) There are variables such as frequency, peak levels, time of exposure and susceptibility of the individual which is based on genetics, immune system function and so on.

What I do is survey a property and compare it to other places that I measure and look more at orders of magnitude rather than a 1-2 milliGauss difference.

Do you know what the level of the fields are in the place you live in now?

Are you aware of what are typical and ordinary values of magnetic fields in other suburban (or urban) homes in the area?

Many homes I have surveyed in the certain urban areas have average interior values of 5 – 8 mG (due to increased power density and decreased utility easement distances) and there are a few homes where I have found 10 – 35 mG. Standing or driving beneath a high power line will have a value of anywhere from 2 – 290 mG so the difference between 1 mG in a home and 2 mG in a home is relatively small in the context and scale of how much fields can and do vary. In deciding what house to live in, you can spend a lot of time and effort trying to find a place that has a lower level like 0.3 mG – 0.5 mG (which is very close to as low as you can get without having electricity at all) but that does not really mean that the home is safer overall to live in for the reasons and risk factors I mentioned above.

There are some environmental factors where a slight change is very noticeable and important to comfort such as temperature – some people find 69 F to be comfortable, but others prefer 72 F. On a planet where temperatures range from below 0 degrees to over 100, that is very small (a few percent difference) but important.

EMF fields are not like that as at the 1 – 2 mG level for example, there is hardly any range left to decrease to 0.0 mG as you are already close to the bottom in what is known as ALARA. (As Low As Reasonably Achievable) Even though 2 mG is 100 % higher than 1 mG and may seem like a large increase, the health risk levels do not behave in a LINEAR fashion as you might find with known toxins. At the worst, it is better to view EMF levels on more of a logarithmic scale (powers of 10) rather than integer multiples.

But in respect to your request I will give you some ranges that in my opinion are fine for where people spend 90 % of their time or more, but I have to emphasize the most of the time part because I do not feel it is beneficial for people to be scared if for a fraction of the time (for instance, even 20 hours a week) the magnetic field exceeds these numbers. Also EMF meters do not always agree with each other because of design and frequency weighting.

Finally, the stress of worrying about EMF causes more damage on average than the EMF field itself as stress itself is a proven health hazard. If you are afraid, children pick up on those emotions and it definitely impacts them. It is good to be concerned and make informed decisions, but I caution people against letting fear overtake common sense and practicality.

And with that thought in mind, one of the unifying concepts I have observed in working with thousands of clients is if they are concerned enough to pay to have an EMF survey because they care that much about their family, they are already doing a lot of the right things to protect themselves and those they love.

Pacemaker / Biomedical Implant Electromagnetic Interference EMI Sources & Issues

While pacemakers and other biomedical implants and implantable devices are somewhat more resistant to electromagnetic interference (EMI) than in previous generations, there are also more sources of potential EMI from new technologies such as hybrid vehicles, wireless chargers and so forth.

For example, the DC magnetic field from headphones can exceed 10 Gauss and can demonstrably interfere with the operation of a pacemaker. Cardiac centers a few years ago did a study and found that up to 15 % of patients with a pacemaker experienced interference issues when headphone came within 1.2 inches of the device, and up to 30 % of patients with an ICD (Implanted Cardioverter Defibrillator) also demonstrated operational abnormalities caused by the close proximity of the speaker.

While cell phones and MP3 players are less likely to cause issues, they should still be kept away from the heart / bioimplant area as there is a chance that RF energy from these electronic device could cause unpredictable behavior. Several years ago, there were some studies that indicated that MP3 players themselves (separate from the magnetic field of the speakers) could not affect a pacemaker, but since then MP3 players have evolved to other transmission modalities which involve using radiated Bluetooth frequencies.

Also, very recent studies (June 2015) have shown that cell phone can influence pacemakers in unexpected ways. At close range (within 6 inches) pacemakers can misinterpret the signal from a cell phone as a cardiac signal which then responds by consequently pausing the cardiac rhythm of the patient and could lead to fainting. For ICDs, the cell phone signal could be mistaken for ventricular tachyarrhythmia and lead to a painful shock as the ICD is programmed to respond to what it thinks is abnormal heart rhythm.

Also, high electric fields such as those beneath high voltage power lines could induce similar behavior if the implants are set to configurations which lower their EMI susceptibility.

Pacemaker ICD Diagram

Pacemaker ICD Diagram