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Air Filtration for Schools

June 28, 2011

“…every child and school employee should have the right to an environmentally safe and healthy school that is clean and in good repair.”

— American Public Health Association

The Problems

The statistics are a bit unnerving; 53 million school children and 6 million teachers, administrators and others walking into 120,000 school buildings every day – at least 50% of these schools have been diagnosed with indoor air quality problems.1

The most precious natural resource of any country is found in their young people and the United States is placing too many kids in jeopardy by exposing them to buildings that are less-than-conducive to a positive, healthy learning environment.

“When taken collectively, schools are a major consumer of energy – some 425 Trillion Btu’s per year, 7% of all energy used by commercial buildings.”


The Department of Energy says, “Our nations K-12 schools are challenged to serve a growing student population and rising community expectations with aging buildings, constrained operating budgets, and ever-increasing energy bills.” Each year, taxpayers spend $6 Billion on energy for these schools – about 25 percent more than necessary. That $1.5 Billion could be redirected to hire 30,000 new teachers or purchase 40 million new textbooks annually.2

Add to this energy bill another alarming statistic:

The American Lung Association estimates Statistics show 6.3 million school aged kids miss some 10 million with asthmas and, as result, asthma is the leading cause of school absenteeism due to chronic illness.3 And the Centers for Disease Control and Prevention estimates approximately 14 Million school days per year lost because of asthma exacerbated by poor indoor air quality in schools.

The American Public Health Association states, “…every child and school employee should have the right to an environmentally safe and healthy school that is clean and in good repair.”

While we know many of the problems of school indoor air quality problems can be solved with good engineering practice and proper Maintenance, Operation, and Repair ( MOR), cleaner air provided by increased levels of air filtration provide the solution upon which many of the IAQ problems develop.

Particulates in the Air

Because schools represent a much denser population percentage than a typical commercial office building, the bio-burden becomes even greater. Viable and non-viable particulates brought in on people’s clothing and through open doors and windows – add to that the activity level of most young people which increases the shedding of skin cells and other particulates – makes school air some of the dirtiest air in any environment.

Many schools utilize low efficiency (MERV 1-4) filters that remove minimal levels of all particulate matter. For any parent who has taken their child to school first thing in the morning and picked them up in the afternoon, the difference in the smell of the school at the end of the day is astonishing. For those in the school, they have become accustomed to the odor and do not realize their air is full of particulates and odors.

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“When the building’s air filters do not remove the particles from the air, the occupant’s lungs become the filter.”

– H. E. “Barney” Burroughs-Building Wellness Consultancy

With these tremendous problems comes tremendous opportunities for collaboration of schools with NAFA Certified Air Filter Specialists (CAFS). NAFA members across the world have stepped forward to help local schools provide better air filtration and cleaner environments for their students.

Here are just two examples:

Case Study #1

Norpsec Filter, Ltd.
Sarnia, ON
President – Bob Jackson, CAFS

Norspec Filtration Ltd. in Canada worked with the Thames Valley District School Board beginning in 2000. TVDSB began to realize that their “low bid” contract for air filters was not working when parents, teachers and custodial staff began complaining. They revised their air filter requirements with the note that they were looking for solutions to their air quality problems.

Norspec made a presentation to TVDSB outlining an “Air Filter Management Program” that included replacement of all low MERV # filters with MERV 8 pleated filters along with MERV 8 synthetic ring and link panels. Next, Norspec assisted with development of a change- out schedule that involved a 3-month survey of all 195 school locations to verify size, quantity, and existing status of the air handling system. Finally, they worked with the school district to assemble a “Filter Committee” with representatives from Norspec, along with school officials and personnel from purchasing, maintenance and health & safety that met on a quarterly basis to assess proposed solutions along with addressing any filter issues brought to the committee.

Each school had its own filter change schedule and filter order sheet with specific times and dates for ordering and changing. The program was monitored by the Filter Committee. This monitoring revealed that the individuals involved in changing air filters knew little about air filtration. With more than 400 people involved, Norspec held 5 training sessions – one in each region of the district. Over the intervening years, this training has become a yearly event to accommodate new personnel and reacquaint existing employees with filtration concepts.

The Filter Committee continues to meet regularly to discuss issues, troubleshoot problems and look for better ways to improve overall air quality. As a result of this partnership between TVDSB and Norspec, the school has realized cost savings from reduced change- outs in many schools, along with reduction of storage and damage.

With the increased in air quality at the schools the Board has reported significant cost savings in other areas such as housekeeping and equipment maintenance. In 2004, Norspec Filter nominated Thames Valley District Schools for the NAFA Clean Air Award which they subsequently received.

Case Study #2

This case study shows the value that NAFA-member companies can bring to facilities with knowledge and training along with higher efficiency filters to help provide clean air in the schools.

Air Industries, Inc.
North Andover, MA
Stephen W. Nicholas, CAFS, NCT

The Keefe Technical School is a 30 year old facility with approximately 300,000 sq. ft. of space. They provide classes and training for (13) different vocational/technical careers including automotive, woodworking, plumbing, electrical and various other trades. They also have a gymnasium, swimming pool and offer several cooking classes as well. The school recently had the Heating, Ventilation, and Air-Conditioning, (HVAC) ductwork and coils cleaned. They were now looking for ways to keep their HVAC system components hygienically clean to improve and maintain acceptable Indoor Air Quality for the students, faculty and staff.

The Plant Engineer, Ken Whidden arranged for instruction, training and testing for custodial and maintenance staff including the HVAC Supervisor Tim Rivers with the latest technology required to maintain the school’s HVAC air filtration systems. The training programs provided included HVAC Air Filtration Choices for Today, The U.S EPA’s Tools for Schools Program as well as Indoor Air Quality. The staff also participated in and successfully completed training and testing of the National Air Filtration Association, (NAFA) Certified Technician, (NCT) program.4

Original Equipment

The original equipment manufacturer (OEM) HVAC air filters were a 20-25% (MERV 6)5 cartridge type filter. These filters remove 35-49.9% of particles in the 3-10 micron size range. The pressure differential gages used were the inclined tube manometer without any gage oil to accurately read air filter pressure drop. The initial (clean) filter static pressure operating @ 400-450 feet per minute, (FPM) is .15” in water gage (w.g.). The gasket material on the filter holding frames and air handler doors was deteriorated and in many instances missing altogether. To replace each filter the technician would spend approximately 4-5 minutes to remove and replace the new (clean) filter cartridge.

Filter Upgrade

The School wanted to upgrade the filtration efficiency to meet or exceed the filter efficiency required by ASHRAE Standard 62.1 “Ventilation for Acceptable Indoor Air Quality” under section 5.9 Particulate Matter (MERV 6). They also wanted to spend less time installing the filters that would allow more time to address other maintenance duties. The other objective was to keep the HVAC system components hygienically clean and to reduce coil and duct cleaning as well. The school also wanted to improve the overall Indoor Air Quality, (IAQ) with higher efficiency air filters.


Several air filter product types were evaluated for:

  • Efficiency/MERV
  • Documentation/Test Reports
  • Construction Quality
  • Initial Cost vs. Life Cycle Cost/Operating Cost
  • Labor/Installation

The products selected for the upgrade were a 4” deep high capacity extended surface pleated (MERV 11) air filter effectively removing 65-79.9% of 1-3 micron size particles. This efficiency level addresses the US EPA PM 2.5 Standard. Particulates of 2.5 microns may potentially cause lung infection and possible disease. These 4” high capacity pleated filters have approximately the same amount of media (26.1 sq. ft.) as the original (MERV 6) 8” deep cartridge filters (29 sq. ft.). The initial clean filter static pressure @ 400-450 FPM is .21” w.g which is a negligible .06” w.g. differential. The 4” filters were installed in the existing filter holding frames with new filter latches. Closed cell neoprene gasket material was installed on the filter holding frames and doors of the air handling equipment. The time to remove and install the 4” filters took approximately 15-20 seconds each compared with an estimated 4-5 minutes it took for the original 8” cartridge type. Magnehelic® gages were properly installed on all air handing units. This allowed the technicians to effectively measure monitor and manage the air filter change-outs by air flow pressure drop. Having the HVAC technicians and custodial staff successfully complete the NAFA Certified Technician program provided the means for the school to have qualified trained technicians with the skills necessary to maintain the HVAC air filtration system providing cleaner supply air to the students, faculty and staff.


The upgraded filter efficiency and long life cycle of the 4” (MERV 11) pleated filters vs. the (MERV 6) 8” cartridge type filters saved on labor and associated disposal costs. The higher efficiency filters will also keep the HVAC ductwork clean while operating the heating and cooling coils at peak energy efficiency. The overall IAQ was also improved with the higher efficiency pleated filters.

Products selected by Ken Whidden and Tim Rivers of the Engineering/Maintenance Department of the Keefe Technical School can be implemented by other school departments and educational facilities that are looking to improve overall IAQ, equipment efficiency and system performance. Building owners and facility managers will also save on valuable energy consumption scheduling air filter change-outs on pressure drop while providing a safe, clean and comfortable Indoor Air Environment for all the students and occupants in our school systems today.

1. NAFA (NCT) Program based on the NAFA Installation Operation and Maintenance of Air Filtration Systems. 2. ANSI/ASHRAE Std. 52.1-1992 Gravimetric and Dust Spot Procedures for Testing Air-Cleaning Devices Used in General Ventilation for Removing Particulate Matter

Cleaner Air and Lower Costs?


The National Air Filtration Association is dedicated to providing training and certification to those involved in providing clean air to building inhabitants. Most of the time, the lowest initial cost air filter is not the lowest overall cost air filter when energy, storage, change schedules and disposal costs are included.

NAFA member companies have the skills and information along with technology tools to help school personnel determine the correct filter for the application, the appropriate change schedule, and the training and certification for air filter technicians that combine to give value and cost savings in most every application.


    1. National Center for Education Statistics, “State Nonfiscal Survey of Public Elementary/Secondary Education: School Year 2001-02, 2003.
    2. Energy Efficiency and Renewable Energy, US Department of Energy,
    3. Coalition for Healthier Schools, Position Statement, 2005.
    4. NAFA (NCT) Program based on the NAFA Installation Operation and Maintenance of Air Filtration Systems.
    5. ANSI/ASHRAE Std. 52.1-1992 Gravimetric and Dust Spot Procedures for Testing Air-Cleaning Devices Used in General Ventilation for Removing Particulate Matter.
Air Filtration for Schools; Fall 2005 issue of Air Media
Authors: Bob Jackson, CAFS Norspec Filtration and Stephen Nicholas, CAFS, NCT II Air Industries, Inc.