Indoor Air Quality Solutions, IAQS

What is the Minimum Efficiency Reporting Value?

The Minimum Efficiency Reporting Value, also known simply as MERV, measures the performance of air purifiers, specifically large purifiers intended to clean an entire house or building. Large, whole-house purifiers are not evaluated in the same manner used to measure the effectiveness of small, portable air cleaners, which are sometimes given Clean Air Delivery Ratings (CADR) instead.

Whole house and building air purifiers usually receive MERV ratings of between 1 and 16, though the upper limit is sometimes extended to 20. Common residential air purification systems tend to fall within a narrower range. Higher numbers translate to more effective air filtration. According to the online encyclopedia Wikipedia, “The scale is designed to represent the worst case performance of a filter when dealing with particles in the range of 0.3 to 10 micrometers.”

MERV Rating Chart

Who Uses MERV Ratings?

The MERV rating system was initially created by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (or ASHRAE for short) in 1987. However, this evaluation system was based on older methods that date back to 1968, when ASHRAE issued “Standard 52,” the first formal testing standard for filters. According to an article by engineer Donald Newell, the purpose of the Standard has not changed since its early days, and is designed to determine the following attributes of air filters:
• Particle removal capability
• Resistance to airflow
• Expected operating life

MERV ratings measure only the first quality, however. The MERV rating of an air cleaner is determined according to updated standards set by the ANSI/ASHRAE Standard 52.2-1999.

How is an Air Cleaner’s MERV Rating Determined?

Air cleaners are given MERV ratings based on the results of a series of tests. Simply put, the process works as follows:
1. Test particles are introduced into the air of the testing area. These particles fall into one of twelve categories, based on size. The smallest category contains particles ranging from .3 to .4 micrometers (also known as “microns”). The largest includes particles from 7 to 10 micrometers.
2. The air is then passed through the filter being tested. The density of particles in the air is measured before and after the air passes through the filter to determine how effective the filter is at removing pollutants in each size category.

After this is done, the process is repeated five more times, so that there are ultimately six measurements for each of the twelve categories. The MERV number is assigned based on the worst result. Hence the “minimum” in “Minimum Efficiency Reporting Value.”

What Does an Air Cleaner’s MERV Rating Mean for You?

A helpful chart detailing what MERV ratings mean can be found at http://www.mechreps.com/PDF/Merv_Rating_Chart.pdf. Of particular interest is the column detailing what types of pollutants are filtered out at each level.

Precise technical details will be less important to the average customer than an answer to the question, “What MERV ratings are acceptable for my home?” The United States Environmental Protection Agency provides some information on this matter. “Medium efficiency filters with a MERV of 5 to 13,” it states, “are reasonably efficient at removing small to large airborne particles. Filters with a MERV between 7 and 13 are likely to be nearly as effective as true HEPA filters at controlling most airborne indoor particles.” Furthermore, the EPA adds that “medium efficiency air filters are generally less expensive than HEPA filters, and allow quieter HVAC fan operation and higher airflow rates than HEPA filters since they have less airflow resistance.”

HEPA (High Efficiency Particulate Air) filters are the top-of-the-line air filters. Most homes are not capable of having whole-house HEPA filtration systems installed without extensive modification. Therefore, the EPA’s recommendation of filters with a MERV rating from 7 to 13 is something that potential customers should keep in mind.

The National Air Filtration Association gives a roughly similar answer. The highest range it recommends for residential systems is 9-12; higher numbers are said to be suited for hospitals or commercial buildings rather than homes.

Limitations of the MERV Rating System

An air cleaner’s MERV rating is based on its ability to filter out undesirable particles from the air. Not all indoor air pollution is particle-based, however. Gasses contribute significantly to pollution as well. The ability of an air purifier to remove particles is not predicative of its ability to remove gasses, so the MERV rating is not helpful in this regard.

Newell’s article cautions that air filters given the ASHRAE test “are likely to perform worse than predicted because of various installation conditions.” This is known as the “installation effect.” Therefore, it is important to remember that MERV ratings are assigned based on a purifier’s performance in carefully controlled testing conditions, and not the “real world.”

And finally, as stated above, MERV ratings are only relevant to large air cleaners intended to affect whole buildings. Common small portable air cleaners do not have MERV ratings.

Conclusion

The MERV rating system is a helpful way to describe the capabilities of different large air cleaners. It is determined through rigorous testing and is gives the worst-case performance of the filter, so the MERV number is not inflated. No one should forget to consider MERV ratings when shopping for such cleaners. There are, however, other factors to consider as well, so it would be a mistake to think that buying the right air filtration system is a simple matter of picking the unit with the highest MERV.

http://www.microshield-es.com/mervfilters.html

John P. Lapotaire, CIEC
Certified Indoor Environmental Consultant
Microshield Environmental Services, LLC
www.Microshield-ES.com

Indoor air pollutants are unwanted, sometimes harmful materials in the air. Indoor air pollution is among the top five environmental health risks. Usually the best way to address this risk is to control or eliminate the sources of pollutants, and to ventilate a home with clean outdoor air.   The ventilation method may, however, be limited by weather conditions or undesirable levels of contaminants contained in outdoor air. If these measures are insufficient, an air cleaning device may be useful. Air cleaning devices are intended to remove pollutants from indoor air. Some air cleaning devices are designed to be installed in the ductwork of a home’s central heating, ventilating, and air-conditioning (HVAC) system to clean the air in the whole house. Portable room air cleaners can be used to clean the air in a single room or specific areas, but they are not intended for whole-house filtration. The following pages will provide information on different types of air cleaning devices and how they work.

Indoor Air Pollutants
Pollutants that can affect air quality in a home fall into the following categories:

•Particulate matter includes dust, smoke, pollen, animal dander, tobacco smoke, particles generated from combustion appliances such as cooking stoves, and particles associated with tiny organisms such as dust mites, molds, bacteria, and viruses.

•Gaseous pollutants come from combustion processes. Sources include gas cooking stoves, vehicle exhaust, and tobacco smoke. They also come from building materials, furnishings, and the use of products such as adhesives, paints, varnishes, cleaning products, and pesticides.

What Types of Pollutants Can an Air Cleaner Remove?
There are several types of air cleaning devices available, each designed to remove certain types of pollutants.

Particle Removal

Two types of air cleaning devices can remove particles from the air — mechanical air filters and electronic air cleaners. Mechanical air filters remove particles by capturing them on filter materials.

High efficiency particulate air (HEPA) filters are in this category. Electronic air cleaners such as electrostatic precipitators use a process called electrostatic attraction to trap charged particles. They draw air through an ionization section where particles obtain an electrical charge. The charged particles then accumulate on a series of flat plates called a collector that is oppositely charged. Ion generators, or ionizers, disperse charged ions into the air, similar to the electronic air cleaners but without a collector. These ions attach to airborne particles, giving them a charge so that they attach to nearby surfaces such as walls or furniture, or attach to one another and settle faster.

Gaseous Pollutant Removal

Gas-phase air filters remove gases and odors by using a material called a sorbent, such as activated carbon, which adsorbs the pollutants. These filters are typically intended to remove one or more gaseous pollutants from the airstream that passes through them. Because gas-phase filters are specific to one or a limited number of gaseous pollutants, they will not reduce concentrations of pollutants for which they were not designed. Some air cleaning devices with gas-phase filters may remove a portion of the gaseous pollutants and some of the related hazards, at least on a temporary basis. However, none are expected to remove all of the gaseous pollutants present in the air of a typical home. For example, carbon monoxide is a dangerous gaseous pollutant that is produced whenever any fuel such as gas, oil, kerosene, wood, or charcoal is burned, and it is not readily captured using currently available residential gas-phase filtration products.

Pollutant Destruction

Some air cleaners use ultraviolet (UV) light technology intended to destroy pollutants in indoor air. These air cleaners are called ultraviolet germicidal irradiation (UVGI) cleaners and photocatalytic oxidation (PCO) cleaners. Ozone generators that are sold as air cleaners intentionally produce ozone gas, a lung irritant, to destroy pollutants.

Ozone is a lung irritant that can cause adverse health effects.

•UVGI cleaners use ultraviolet radiation from UV lamps that may destroy biological pollutants such as viruses, bacteria, allergens, and molds that are airborne or growing on HVAC surfaces (e.g., found on cooling coils, drain pans, or ductwork). If used, they should be applied with, but not as a replacement for, filtration systems.

•PCO cleaners use a UV lamp along with a substance, called a catalyst, that reacts with the light. They are intended to destroy gaseous pollutants by converting them into harmless products, but are not designed to remove particulate pollutants.

•Ozone generators use UV light or an electrical discharge to intentionally produce ozone. Ozone is a lung irritant that can cause adverse health effects. At concentrations that do not exceed public health standards, ozone has little effect in removing most indoor air contaminants. Thus, ozone generators are not always safe and effective in controlling indoor air pollutants. Consumers should instead use methods proven to be both safe and effective to reduce pollutant concentrations, which include eliminating or controlling pollutant sources and increasing outdoor air ventilation.
Visit http://www.epa.gov/iaq/pubs/ozonegen.html for more information on ozone generators sold as air cleaners.

John P. Lapotaire, CIEC
Certified Indoor Environmental Consultant
Microshield Environmental Services, LLC
www.Microshield-ES.com

Jason Earle. Founder and CEO of Mycelium Holdings LLC
Posted: 07/02/2012

With 50 Percent of Childhood Asthma Uncontrolled, Time to Look Homeward

“Despite available treatments, less than 50 percent of asthmatic children control their symptoms,” announced Prof. Nikos Papadopoulos, Chair of the International Consensus (ICON) on Pediatric Asthma, two weeks ago at The European Academy of Allergy and Clinical Immunology (EAACI) 31st Annual meeting, Geneva, Switzerland.

As a childhood asthmatic, and someone who has long worked with families to regain control of their indoor air, that number nearly knocked me off my chair.

Granted, many of the worst cases of asthma exist in developing nations where there is, sadly, little anyone can do about it. This is largely due to substandard living conditions and poor education, compounded by inadequate medical care. When people cook over unventilated open flames indoors, asthma is bound to rear its ugly head. Combine that with a whole host of other variables and you have yourself an epidemic.

But more disconcerting are the cases here in our own backyard, where we have the ability to do something about it, yet we’re still not doing all that can be done.

It’s well known there are higher concentrations of asthmatics in urban environments, especially in close proximity to highways, but asthma is an equal opportunity ailment. It affects people across the whole human spectrum, with kids being the hardest hit.

While medications are an important part of controlling symptoms — they save lives every single day — one of the most overlooked aspects of asthma prevention is the home environment, where many children spend most of their time. In essence, asthma = inflammation + irritation. Most of the irritants that trigger asthma symptoms are avoidable, and really have no place in a healthy home.

-Dampness of any sort, which invariably leads to:

•Mold growth
•Dust mites
•Pests

– Noxious chemical cleaners

– Air fresheners

– Candles

– VOCs

– Cigarette smoke (does this even need to be said?)

– Carpet in the basement (yes, I know, it’s common, but so are most mistakes)

– And much, much more.

I’ve written about this in the past. Here’s a a piece I did about spring cleaning that elaborates on these items in greater detail, if you’re so inclined to dig deeper.

There was a time when doctors made house calls. These have been supplanted by eight-minute clinic visits. Symptoms are discussed, but underlying causes are rarely explored. Physicians simply have no practical way to know what’s going on in the home, nor do they have the time to pursue it. While numerous studies have been done proving the positive impact of custom, home-based environmental interventions directed at educating the affected and reducing asthma triggers indoors, it has not been done consistently on a large scale.

Interestingly, the CDC Community Preventive Services Task Force put out a report late last year in which they recommend these home-based initiatives. The report cited extensive data showing that a relatively small investment in these programs can yield significant health care savings, reduce the number of missed school days, increase the productivity of the parents who would otherwise miss work to care for their children and, of course, improve quality of life for the whole family.

The average person spends more than 90 percent of every day indoors, yet we hear relatively little in the media about what we’re doing to our indoor environment. Buildings are built tighter to save energy, while a dizzying array of pollutants accumulate indoors, all helping to steadily increase the reach and cost of a disease that should already be on the decline. It’s part of our modern condition.

There is much that can be done at relatively low cost. Most synthetic cleaning products, for example, can be swapped for natural versions (many of which work better!); air fresheners can be jettisoned in favor of HEPA air purifiers and HEPA vacuum cleaners, and pillows, mattresses and bedding can be fitted with allergen encasements. Some homes require professional help, especially those with serious moisture, mold or pest problems, but a great percentage will benefit from minor to moderate interventions.

The home environment is what I call the last mile in asthma treatment and prevention. It is where education and awareness can help turn the asthma juggernaut around, and where more attention needs to be directed. The solutions to much of this suffering are hiding in plain sight.

John P. Lapotaire, CIEC
Certified Indoor Environmental Consultant
Microshield Environmental Services, LLC
www.Microshield-ES.com

Face it. Anywhere in Florida makes for a great place to live. Yet every home endures a certain amount of unwanted, indoor air pollutants. In fact, the United States Environmental Protection Agency (EPA), ranks indoor air pollution as one of the top five environmental health risks faced by U.S. citizens.

Indoor air pollution builds up via in-home activities such as cooking, cleaning and even indoor remodeling projects. To eliminate the associated risk factors, a Florida homeowner could attempt to replace the indoor air with cleaner outdoor air. However, residential ventilation systems usually don’t include outdoor air supply.  If you consider opening a window that could occasionally be rendered inefficient due to unfavorable weather conditions, elevated humidity, or extreme accumulations of contaminants in the outdoor air.

At times, homeowners must embrace alternative indoor air cleaning methods. Some residents of Florida are known for making use of indoor air cleaning devices and products that attach to your homes air handler such as UV lights or hydroxyl and ozone generators in an attempt to disinfect purify or destroy air contaminants before they are recycled back into their home air supply.  But those are just bells and whistles that don’t actually correct the issue.

We recommend that you begin the improvement of your indoor environment using the 7 Principals of Healthy Homes.

1. Dry:
Damp houses provide a nurturing environment for mites, roaches, rodents, and molds, all of which are associated with asthma.

2. Clean:
Clean homes help reduce pest infestations and exposure to contaminants.

3. Pest-Free:
Recent studies show a causal relationship between exposure to mice and cockroaches and asthma episodes in children; yet inappropriate treatment for pest infestations can exacerbate health problems, since pesticide residues in homes pose risks for neurological damage and cancer.

4. Safe:
The majority of injuries among children occur in the home. Falls are the most frequent cause of residential injuries to children, followed by injuries from objects in the home, burns, and poisonings.

5. Contaminant-Free:
Chemical exposures include lead, radon, pesticides, volatile organic compounds, and environmental tobacco smoke. Exposures to asbestos particles, radon gas, carbon monoxide, and second-hand tobacco smoke are far higher indoors than outside.

6. Ventilated:
Studies show that increasing the fresh air supply in a home improves respiratory health.

7. Maintained:
Poorly-maintained homes are at risk for moisture and pest problems. Deteriorated lead-based paint in older housing is the primary cause of lead poisoning, which affects some 240,000 U.S. children.

John P. Lapotaire, CIEC
Certified Indoor Environmental Consultant
Microshield Environmental Services, LLC
www.Microshield-ES.com