Category Archives: Indoor Air Quality (IAQ) Testing

Residential Radon Gas Testing – Mold and Indoor Air Quality Inspection by ScanTech Technical Consulting

Radon is one of the leading causes of lung cancer

Radon is one of the leading causes of lung cancer in the United States

In a rush to test your home for radon gas or radioactivity in natural stone such as granite or marble? Did you know that radon is the 2nd leading cause of lung cancer? (Smoking is 1st and radon gas synergistically increases mortality rates for smokers)

While it is not well known, radon gas levels EXCEED EPA action limits of 4 picoCuries/liter (pCi/L) in up to 10 % of all homes in Dallas county with an additional 14 % falling into the marginal range of 2 – 4 pCi/L. This means that 1 out of 4 homes (10 % + 14 % = 24%) in Dallas either have a radon issue or fall into a caution category. Other counties, such as Tarrant, Collin and Denton are not immune either. (see the link below on Radon FAQ from ScanTech for more details)

Example areas of the Metroplex (not a complete or comprehensive list) which have been found by ScanTech testing to have excess radon levels which are statistically higher than the 24 % quoted above include:

  • North Dallas and Far North Dallas
  • Lake Highlands
  • University Park
  • Highland Park
  • Park Cities area
  • Richardson
  • Arlington

ScanTech now has the capability to test and get results within as little as 24 hours of initial deployment using a high quality digital tester in case your option period is about to expire.

Our services are both faster and cheaper than competing methods or companies and we have been performing radon testing for homeowners in the DFW area for over 10 years.

Testing is performed by an engineering graduate experienced in radioactivity measurements,  indoor air quality testing including mold inspection, formaldehyde and radon gas testing.

AARST NRPP National Radon Testing Professional Certified

AARST-NRPP Nationally Certified Radon Residential Measurement Provider ID # 108991 RT*

*Meets HUD, Fannie Mae, Freddie Mac and GSA requirements

Mold Assessment Consultant – Texas Dept. of Health Service License # MAC1387

(Activated charcoal short term radon test kits are accurate as well, but typically require at least 4 business days to get results under best case conditions and a complete kit deployment and pickup service is almost always more expensive due to the additional travel)

Call / text to 214.912.4691 – please include physical address, square footage property and email

More information is available here:

RADON FAQ Dallas /Fort Worth — DFW North Texas Area

Radon Deaths United States Annually

Annual Radon Deaths Updated Chart

Cities for radon / air quality inspection services include: Dallas, Austin, Houston, San Antonio, Spring, The Woodlands, Round Rock, 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, Duncanville, Lancaster, Rowlett, Royse City, Trophy Club, Southlake and Hurst. Counties served include Dallas, Collin, Denton, Tarrant and Rockwall County.


Indoor Air Quality (IAQ) Testing Services (including chemicals / carcinogens like Formaldehyde) Available – Fast Onsite Results!

Formaldehyde NFPA Diamond from MSDS (Material Safety Data Sheet)

Formaldehyde NFPA Diamond from MSDS (Material Safety Data Sheet)

ScanTech Technical Consulting performs indoor air quality tests including particulate matter in the air (residential and commercial) in the 0.5 – 2.5 micron and 2.5 micron + range  (PM 2.5 and PM10) in order to evaluate how clean your air is with respect to dust and other fine particles. We also offer formaldehyde and VOC levels testing due to chemicals used in the manufacture of pressed wood flooring, lumber, laminates, glues and other adhesives in your home and factory/office.

More information on formaldehyde can be found here:

We can also test for VOCs, (Volatile Organic Compounds) CO2 (Carbon Dioxide) levels and O2 oxygen levels in your home to check ventilation quality. Datalogging over time available to show trends and measure the effects of HEPA filtration and electrostatic air ionization units.

Our background in organic and environmental chemistry, epidemiology, advanced microbiology, medical geology  and human physiology makes us uniquely qualified to answer your concerns regarding the invisible environment you breathe every day.

July 2016 ruling by the EPA on the emissions of formaldehyde of wood products produced or imported into the United States:

The following tables and information are from:

Health Effects Notebook for Hazardous Air Pollutants

To convert concentrations in air (at 25°C) from ppm to mg/m3: mg/m3 = (ppm) × (molecular weight of the compound)/(24.45) For formaldehyde which is CH20: 1 ppm = 1.23 mg/m3.

Explanation of Formaldehyde Levels

Formaldehyde Regulatory and Health Levels Comparison

Formaldehyde Regulatory & Health Levels Comparison

AIHA ERPG–American Industrial Hygiene Association’s emergency response planning guidelines. ERPG 1 is the maximum airborne concentration below which it is believed nearly all individuals could be exposed up to one hour without experiencing other than mild transient adverse health effects or perceiving a clearly defined objectionable odor; ERPG 2 is the maximum airborne concentration below which it is believed nearly all individuals could be exposed up to one hour without experiencing or developing irreversible or other serious health effects that could impair their abilities to take protective action.

ACGIH STEL–American Conference of Governmental and Industrial Hygienists’ short-term exposure limit expressed as a time-weighted average exposure; the concentration of a substance which should not be exceeded at any time during a workday.

LC50 (Lethal Concentration50)–A calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.

NIOSH IDLH–National Institute of Occupational Safety and Health’s immediately dangerous to life or health limit; NIOSH recommended exposure limit to ensure that a worker can escape from an exposure condition that is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from the environment.

NIOSH REL–NIOSH’s recommended exposure limit; NIOSH recommended exposure limit for an 8- or 10-h time-weighted average exposure and/or ceiling.

OSHA PEL–Occupational Safety and Health Administration’s permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek.


Radon Gas Risk Factor Safety Levels Comparison

How do you put the risk from radon into perspective, especially since all homes contain some level of radon gas in them and there is no “safe level” except zero?

I have found the following charts to be helpful in evaluating risk: (please click on the pictures for a full sized detailed view)

Radon Gas Safety Cancer Risk

Radon Gas Chart Safety Level Relative Risk Factors

Radon Risk Smokers Non-Smokers

Radon Risk Chart for Smokers vs. Non-smokers

Notice that the risk for a radon level at the EPA action limit of 4 picoCuries/liter is similar to the same risk of dying in a car wreck. I have personally observed several residences that I have tested in Dallas county to EXCEED this limit including my own home.

Radon is linked to not just lung cancer, but recent epidemiological evidence also suggests that radon gas may also be a risk factor and contributor to

  1. Acute Myeloid Leukemia (AML)   13 % – 25 % of all cases worldwide.
  2. Kidney cancer
  3. Certain childhood cancers
  4. Melanoma

Radon Gas Testing Methods & Equipment

There are a variety of ways to monitor the radon levels in a residence, home or commercial building and the best detector for your needs depends on balancing cost, accuracy, ease of use and type of application such as a long or short term test.

The chart below gives a comparison of different detectors including the time period duration during which radon is measured.

Comparison of Different Radon Detection Methods

Comparison of Different Radon Detection Methods

Radon & Radioactivity Measurement Safety Guide

Measuring radioactivity from radon is potentially very confusing for the lay person for several reasons. One of which is that there are several different units of measurement depending on the application, era of standards and preference based on world regionalisms. Applications include activity, (which radon measurement falls under) absorbed dose, which is the measure of radioactive energy absorbed by tissue per unit mass and dose equivalent which is the measure of absorbed doses from DIFFERENT types of radioactivity such as alpha, beta, and gamma radiation. Many scintillation meters still measure this in the older measurement unit rem (Roentgen Equivalent Man) or microrems for gamma radiation.

For instance, when measuring radon, North America prefers to use the picoCuries per liter (pCi/L) designation as opposed to Becquerels  or Bq / meter^3 which is typically used in Europe and the UK. These both measure a specific number of atomic disintegrations per volume of space.

In the case of the Becquerel, this is 1 atomic disintegration per second or 60 events per minute. For a picoCurie, this is translated as 2.2 radioactive disintegrations per minute. A convenient conversion chart is shown below.

Just as a quick conversion from the picoCurie/liter to the Becquerel / m^3:

1 picoCurie / liter = ~ 37.1 Bq/m^3     EPA action limit 4 pCi/L = ~ 148.4 Bq/m^3

Units of Measurement for Radioactivity and Dose

Units of Measurement for Radioactivity and Dose

As an added note, a little known unit of radon is what is known as a Working Level (WL) which is the quantity of radon that will produce 1.3 X 10^5 MeV (Mega Electron Volts) of potential alpha particle energy per liter of air. A single WL of radon is equal to the RDP’s (Radon Decay Products) in equilibrium with 100 pCi/L of radon. Because the equilibrium value for RDP’s for indoor environments is typically 0.5, radon concentrations of 1 WL would be around 200 pCi/L.

Entry Routes and Factors Affecting Indoor Radon Levels in Homes

Many people wonder how radon gas levels could be present in Dallas / Fort Worth Metroplex DFW area – how does it get inside your home and affect your health and safety?

The fact is that all parts of the Earth, regardless of geography, have some level of background radiation due to nuclear disintegrations of naturally occurring radionuclides (radioactive isotopes) including uranium in the soil, water and air. On average, rocks contain only about 1-3 ppm of uranium, though some species have as much as 100 ppm. These are typically metamorphic minerals such as granite, black shale, schist, gneiss, phosphorites, some sedimentary rock (including limestone in some cases) with a high phosphate content and metamorphic rocks derived from these rocks.

On average worldwide, the radioactive concentration of U-238, Thorium-232 and Radium-226 are ~0.65 pCi (picoCuries) per gram though this can vary significantly in very localized areas.

Radon geology home construction

Radon Intrusion Paths into Home

The major source of indoor radon is soil gas transported by pressure-induced convective flows (as shown in the illustrations) with potential entry points marked. Radon transport is enhanced when the base of the building is under significant negative pressure. Homes built on soils with higher radon release (based on soil type, porosity, pore volume, water content, etc.) and convection based transport are typically more sensitive to atmospheric factors such as temperature, wind and barometric pressure. Radon movement through soil can also occur through diffusion or both diffusion and convection.

Homes built on soils with a higher clay content (as opposed to those with sandy / gravelly soils) tend to have lower radon gas levels, but there may be trade-offs with higher moisture levels which can give rise to issues with mold, dust mites and general structural deterioration.

What are the major entry routes into your home?

1) Cracks in concrete slabs

2) Spaces behind brick veneer walls that rest on uncapped hollow-block foundations.

3) Pores and cracks in concrete blocks.

4) Floor wall joints.

5) Exposed soil as a sump.

6) Drain tile, if drained to an open sump.

7) Mortar joints.

8) Loose fitting pipe penetrations.

9) Building materials including some rocks and other decorative stones such as marble and granite.

10) Drinking / tap water.

11) Open tops of block walls.


Atmospheric Factors with Radon Levels in Homes

Atmospheric Factors with Radon Levels in Homes (Animated Graphic)

What factors affect indoor radon overall?

1) Low ventilation rates.

2) The nature of soil permeability. (by diffusion / convection mechanisms)

3) Construction materials used. Can be a significant factor in natural stone where Radium-226 concentrations are elevated. (exceed 1 pCi/gm or 1 picoCurie per gram) Emanation depends on radium density and material porosity.

4) Home water supply.

5) Meteorology (such as temperature, pressure and humidity) and the local geology of the environment.

6) Soil radon production rates based on radioactive material composition (most in the U.S. have base radon concentrations between 200 – 2000 pCi/L)

7) Cracks and fissures in the underlying geology

8) Building substructure (slab on grade, pier and beam, basement, etc.)

So Much of Texas is Considered Zone 3: Is it Safe? (free from Radon Gas)

I recently had a client inquire about my services and asked for an official proposal. Before I could respond, within 30 minutes they sent a follow up message saying that because the Dallas / Fort Worth area is considered a Zone 3 region according to the EPA, that testing isn’t necessary.

This is a serious misunderstanding of what the different radon gas Zone designations mean, even according to the Environmental Protection Agency which states explicitly on their website:

“All homes should be tested, regardless of zone designation.”

“All homes should test for radon, regardless of geographic location or zone designation.”

While a structure located in Zone 3 has a statistical likelihood of having a lower level of radon, there are still thousands of homes, residences and structures in the DFW area that will exceed the action limit of 4.0 picoCuries per liter if tested. I have found several myself in the course of testing as this percentage of homes is 10 %. It is not probable, but a 1 in 10 chance is fairly high when gambling against the chance of lung cancer.

I have found a number of homes in the North Dallas area (including mine) whose radon levels are high enough to warrant mitigation. With radon gas now killing more people than drunk drivers, it is well worth the small investment to get your residence checked.

MERV (Minimum Efficiency Reporting Value) Ratings and Filters

You generally cannot place a True HEPA filter in your air furnace because of the flow restriction would place too heavy a load on the blower unit. But you can get a higher efficiency MERV filter that can give some of the benefits of better filtration and indoor air quality without unnecessarily straining the HVAC unit or restricting the air flow.

But to get a good balance between clean air and not damaging your HVAC unit, consult with an air conditioning professional and / or consult with the manufacturer regarding the recommended MERV filter range that can be used in your particular model. Also, the higher your MERV rating, the more often you may have to check and/or change it as it will tend to clog faster.

MERV ratings are numbers that generally measure the quality of an air filter, but can be hard to understand without some context and this chart is a handy reference.


MERV Chart Air Quality

MERV Rating Chart with application comparisons   *Note – the pm size designations listed should be in um or microns

Allergens Air Purifiers

Air Purifier Guide to Size Ranges of Allergens in microns (millionth of a meter or um)

The MERV rating is a filter standard established by ASHRAE  (American Society of Heating, Refrigerating and Air-Conditioning Engineers) but when you shop for a filter online, you may also find references to MPR and FPR.

MPR (Micro-Particle Performance Rating) is a standard used by 3M (notably the Filtrete series) that rates filter performance with respect to the ability to screen out sub-micron (less than 1 um) particles, but can be confusing when comparing to MERV. Note that less than a micron is on the low end of the PM2.5 Fine particle range as designated by the EPA. (0.5 – 2.5 microns)

FPR (Filter Performance Rating) works a little like MERV numbers (but on a 4 – 10 color coded scale) developed by Home Depot for filters they sell including Honeywell.

To get a relatively close comparison, the following chart may be useful when shopping for a more suitable HVAC filter.

MERV MPR FPR Ratings Compared and Explained from

MERV MPR FPR Ratings Compared and Explained from (not endorsed by ScanTech)

While this chart is useful, it is not guaranteed to completely stop all of the biological and inorganic contaminants that are listed. Your mileage may vary.

MERV Filter Models


Composition of Dust Particles and Particulate Matter in The Air

When I test for PM2.5 and PM10 which are Fine Particle and Coarse Particle designations used by the EPA, I am often asked what is the nature of this particulate matter. These may also be referred to as TSP (Total Suspended Particulate) or RSP (Respirable Suspended Particulate) matter. While it is very difficult to tell exactly what it is without microscopic analysis and will vary depending on the environment, an educated guess can be made based on what sources are nearby and the potential contribution of those sources based on typical size regimes.

Possible sources are pollen, toxic mold spores, smoke, bacteria, pet dander, construction dust, etc.

There are some useful reference charts that not only talk about the ranges of certain pollutants, but also give an indication of different filtration mediums which are relatively effective in removing these contaminants.


Particulate Matter in Air Quality

Air Filtration with Regard to Particle Size

*NOTE – HEPA (High Efficiency Particulate Air) filters are typically rated at 99.97% efficiency for particles of 0.3 um or larger. At this time, I am not sure that a HEPA filter will remove more than 95% of particles which are 0.01 microns in size as this chart seems to imply.

Also, beware of filters and vacuum cleaners which claim to be “HEPA-like”, “HEPA-type” or “99% HEPA” as these are not true HEPA filters and are often inferior in quality with regard to air filtration efficiency.

BTW – the term DS efficiency mentioned in the Pleated Filter (40% DS ) refers to Atmospheric Dust Spot Efficiency which measures how well a filter removes staining dust from the air.


HEPA Air Filtration Particle Ranges

HEPA Filtration Particle Chart


Particle Filtration Size Chart HEPA vs. ULPA

Particle Filtration Size Chart HEPA vs. ULPA


Characteristics of Particles and Particle Dispersoids

Characteristics of Particles and Particle Dispersoids

This is a fairly technical diagram for general reference use.


Origin of Dust Particulate Matter

Origin of Dust Particulate Matter

Water Filtration Particle Sizes and Composition for Contamination Control

For aqueous media such as drinking water, here are some reference charts which compare ranges of relevant pollutants, and suggest different filtration mediums which are relatively effective in removing these contaminants.

Particle sizes thin film membrane filtration

Particle sizes thin film membrane filtration

*NOTE – there is an error in this chart at the very top. Instead of pm which is traditionally for picoMeters, the correct unit should be in um or microMeters. (Microns)


Water Filtration vs Particle Size

Water Filtration vs Particle Size


Water Filtration Particle Size Chart Common Contaminants

Water Filtration Particle Size Chart Common Contaminants