Air Quality Guide – How to control pollutants and allergens

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Posted by: George Chrysochou Category: Research Papers Comments: 0

Air Quality Guide – How to control pollutants and allergens

Air Quality Guide

the need for indoor air quality

Source Control

Achieving a high level of Air Quality is not an easy task. As many experts will agree, usually the best weapon against indoor air pollution is source control. Effective source control requires the occupant to deal directly with the problem from its originating source and  it’s usually the fastest, most efficient and cost effective option to deal with indoor air quality issues.

Source control can be distinguished in general precaution measures one may take to deal with possible sources of contamination and focused control measures to react to existing and identified polluting sources.

Source control can reach its maximum potential with what the author of this paper calls the A.I.R. strategy:

A stands for Awareness of indoor air quality issues, I for Insight on the possible sources and the available measures, and R for a direct Response to the situation.

Awareness is the first step in this process and usually the most important one since it solves the problem before it even arises.  Awareness requires the occupant to be aware of indoor air  pollution  problems  and  recognize  the  importance  that  indoor  air  quality  in  his  life. Without a genuine concern and interest for IAQ the occupant will might ignore and miss all the IAP indicators that could be even life-threatening to him in the future. Awareness of the indoor air pollutants and their health effects and basic knowledge on how to maintain a good air quality within your home is essential since besides alerting the occupant when an IAQ problem arises, most importantly it leads to basic preventive measures that are the most cheap and effective way for one to protect him and his family long-term health.

Insight can come before or after a problem arises and requires for an in-depth knowledge of the IAQ matter under concern. When a person is equipped with good basic knowledge on IAQ as suggested in the Awareness stage, he can be readily available to get a deep and effective insight regarding the issue that threatens his indoor air environment. Therefore, the alerted occupant can do personal research and get practical information on which steps he has to take to deal with his IAP issue effectively and cost-consciously. For example, if a person is building a new house, he might get some insight on choosing the most suitable ventilation system that will prevent him from IAQ concerns in the future. Similarly, if a person faces some BRI symptoms he can quickly identify the severity of the situation and deal with it appropriately before it becomes life-threatening.

Response, the last A.I.R. strategic step can also be taken either ex-ante or ex-post of IAP symptoms  and  is  basically  a  call  for  agile,  methodic,  knowledgeable  action.  Once  the occupant has been aware of the IAQ situation and got a good insight for it, Response is the actual  test  of  applying  that  information into practice.    Responses to IAQ  issues  can be numerous, however highly effective and cost-conscious responses are just a few, and that is one of the primary reasons of the existence of this paper.

The A.I.R. strategy is unified process that starts from being interested in your own health, and ends in taking measures to maintain it. Simply waiting for IAQ symptoms to happen for you to take action about them means that you already compromised your health and that you need to take more additional, expensive and time consuming measures to fix the problem. Therefore the AIR strategy is suggested not just when problems occur but also before that, as a preventive measure.

Table 2, presented in the previous chapter, has a great variety of source control measures that can be taken in both the preventive or in the treatment stage. Even though a complete source control approach is not recommended for time and cost concerns, still there are some basic source control measures that could be taken in any circumstance, as the homeowner starts expanding his knowledge on IAQ.  In this paper, we do propose the basic source strategies that need to be taken regardless, and still leave some room for flexibility to the homeowner to add his own measures to the mix.

Selection and cost criteria

Regarding the selection of systems used in this paper, certain global market products  were chosen that fulfilled specified minimum quality requirements based on the academic literature and on  IAQ expert’s feedback.

The general criteria  for the selection process were that the system has to be of good construction quality and effective in treating certain air quality issues at the most suitable price. By those concerns, highly effective but prohibitively expensive systems were excluded from the list, and similarly very cheap systems with low efficiency and durability were also excluded. After narrowing out list to certain products that fulfilled all criteria, an average cost was calculated for them and then transposed to the cost tables. Then underlining costs were further broken down into one-time costs such is the installation and actual products price and into yearly reoccurring costs such is the costs for new filters, maintenance and electricity. A detailed review of which specific systems were used and their components, specifications and underlining costs can be found at the appendix section..

Source control systems used

The different source control systems mentioned in the paper are the following:

S1: Refers to all the basic pre-emptive source control measures on homeowner should take regardless if symptoms occur or not. Basic source control involves systemically cleaning the house with non-VOC or other chemical emitting household products made of purely natural materials.   Those   products   can  be   organic  or   natural  cleaning   liquids,  disinfectants, detergents, laundry products, perfumes, deodorants, air fresheners etc. If the option of choosing solely organic or natural products is not feasible for cost concerns, exceptions can be made but every product of chemical origin should be checked by the homeowner for containing VOC  and  other pollutant  emitting  ingredients.  Table  2, along with additional research can be great means in identifying which products and ingredients may have a negative IAQ effect.

In addition to that, a periodical thorough inspection of the whole house and its perimeter is needed to identify any possible pollutant emitting sources and treat them on the spot, following the suggestions found again at Table 2 and by doing additional research. Some basic  knowledge  and  an  attitude  of awareness  (as  proposed  in the  A.I.R. strategy)  is a prerequisite for identifying those sources on the first place.

S1r: Refers to all the recommendation for S1 but with the addition of radon mitigation measures, in case that the radon test kit (which a monitoring system that will be explained further later) has shown concentrations for the radioactive gas above 4 pCi/L which is the EPA’s benchmark for action.

The radon mitigation measures costs vary greatly but for most cases a passive radon mitigation  system  involving  the  installation of  some  local exhaust  air ducts  or/with the installation of radon insulation floors at the basement are relatively cheap and effective alternatives and the author recommendation for most cases. 6

In rare occasions that all passive radon mitigation systems fail to reduce the limit below the benchmark value, active mitigation systems need to be taken, that include among other the installation of a local exhaust ventilation systems using high airflow air motors. However, due to their higher costs and to their efficient substitutability by passive measures, the active measures have not been included in the cost equations.

S2c/d: Refers to the controls measures that should be implemented in the case of an SBS sickness, that has however a de facto unidentified origin. That means that the source control measures cannot focus on a specific source but instead should a target the potential source s that fulfill the criteria for the current symptoms that the homeowner is experiencing. By treating those potential sources, and giving some time to see the results, the homeowner may solve the problem or at least narrow down the potential sources and increase the controlling efforts on them until the problem is solved.

Table 3 (Burroughs & Hansen, 2011)  can then be used to identify the different complexes of symptoms  and  match  the  possible  contaminants  with  those  found  on  table  2,  and accordingly take the suggested corrective measures.

Table 3 

SBS symptoms, contaminants and possible sources



Symptom Complex






Primary Sources












Eye Irritation / Watery




Incomplete Combustion Burning, dry gritty  stoves,

fireplaces, ETS








Artificial Light , Low Relative Humidity

FormaldehydeBuilding products & furnishings


Paints, air fresheners, carpeting, cosmetics, printers, ETS, dry cleaning products, solvents, aerosol sprays, glues, household products, fuels


Ventilation systems, humidifiers, dehumidifiers, wet insulation, drip pans, cooling coils in AHUs, people pets, plants, insects, outside air



Combustion products, ETS, dust, dirt, maintenance products, building product deterioration, outside air



Nasal congestion /




Incomplete Combustion Burning, dry gritty  stoves,

fireplaces, ETS




Low Relative Humidity, High Temperatures

FormaldehydeBuilding products & furnishings


Ventilation systems, humidifiers, dehumidifiers, wet insulation, drip pans, cooling coils in AHUs, people pets, plants, insects, outside air





Dry throat, Shortness fo breath without lung infections or bronchial asthma




Incomplete Combustion Burning, dry gritty  stoves,

fireplaces, ETS







Low Relative


FormaldehydeBuilding products & furnishings


Paints, air fresheners, carpeting, cosmetics, printers, ETS, dry cleaning products, solvents, aerosol sprays, glues, household products, fuels
ETSPassive Smoking, Active Smoking


Combustion products, ETS, dust, dirt, maintenance products, building product deterioration, outside air
Headache, Fatigue, Malaise, Headaches — frontal, Poor concentration, Dizziness, Tiredness, Irritability 


Ventilation systems, humidifiers, dehumidifiers, wet insulation, drip pans, cooling coils in AHUs, people, pets, plants, insects, outside air 

Ergonomic conditions, Noise & vibrations



Paints, air fresheners, carpeting, cosmetics, printers, ETS, dry cleaning products, solvents, aerosol sprays, glues, household products, fuels


nausea, ringing in ears, pounding heart





Incomplete combustion: vehicle exhaust, stoves, fireplaces, ETS, gas appliances, heaters, outside air

Warm air, low relative humidity, excessive air movement
FormaldehydeBuilding products & furnishings



Skin Irritation, dryness, rashes



Paints, air fresheners, carpeting, cosmetics, printers, ETS, dry cleaning products, solvents, aerosol sprays, glues, household products, fuels 



Warm air, low relative humidity



Ventilation systems, humidifiers, dehumidifiers, wet insulation, drip pans, cooling coils in AHUs, people pets, plants, insects, outside air
FormaldehydeBuilding products & furnishings


S2a/b:  Refers  to  the  controls  measures  that  should be  implemented  in the  case  of an identified BRI condition which is a medically diagnosable microbial sickness. Then there two actions that should be taken immediately: First all the residents and visitors of the house should see a medical specialist, preferably a pulmonologist, and follow his treatment.

Then attempts to eliminate the contaminants source should be implemented, by that meaning  that  all  potential  breeding  grounds  of  the  disease  should  be  checked  and disinfected appropriately but also that all surfaces and objects that in the house should be also cleaned and disinfected as well.

Suggested disinfectants are natural antimicrobial products such as tea tree solutions, which are proven to be more effective in countering the legionella virus than chemical antimicrobials such as the controversial triclosan that is commonly found in commercialized hand soaps and disinfectant. (Mondello, Girolamo, Scaturro, & Ricci, 2009)

Table 4 (Burroughs & Hansen, 2011) presents the potential complexes of symptoms found on most common BRIs. Using the information found one table 1 and combining the symptomatology with the one  described on table 4, the BRI affected  person can easily exclude the option of a SBS condition and he can also have a strong indications on which is the specific microbial agent that he is facing.

Nevertheless, those self-diagnosis tables are not intended to replace the necessity of visiting a doctor to treat the sickness, but rather as mean from the homeowner to identify faster the severity of his condition and take some source countering measure to prevent the spread of the contamination to other persons, especially those living in the same house.

Table 4 

BRI symptoms and possible sources


Symptom Complex




Carrying Agent


Primary Sources

headache*fever*chills *

dry cough* chest pains myalgia vomiting abdominal pain diarrhea

weight loss shortness of breath












Legionella pneumophila

cooling towers

evaporative condensers shower

hydro-therapy units stagnant water systems, Jacuzzi

water fountain, waterfalls water faucets

hot water

fever & chills*coughing*

breathlessness joint pain myalgia polyuria

weight loss lethargy





Humidifier Fever












aerosols from cooling towers water systems

stagnant water

evaporative condensers showers

headache*fever*chills *

dry cough* chest pains myalgia lethargy

shortness of breath no pneumonia





Pontiac Fever






headaches*fever &

chills*dry cough * shortness of breath malaise & myalgia lung disorders

skin irritation














microorganisms endospores animal protein


People pets plants insects

Outside air Ventilation systems humidifiers


cooling coils dehumidifiers wet insulation drip

headaches*fever &

chills*dry cough * shortness of breath malaise & myalgia lung disorders

eye irritation










headaches*fever & chills*cough* respiratory infections




Fungal Infections


molds spores fungi

Ambient air duct work pets

insects plants

Water damaged materials



Viral Infections




people pets insects


* symptoms that are common in all BRIs

S3a/b/c/d: Refers to the focused source control measures taken by the professional IAQ team. Since those measures are usually a product of a professional monitoring system, they are usually very effective in achieving the desired goal from their first application. However, the cost for those is often bloated from choosing an over-the-top solution since the expert may be inclined to promote such recommendations.

General Control

General controls for this research basically mean all the systems that target a broad class of contaminants by mostly using dilution control in cases such as mechanical ventilation and extraction control in cases of air cleaners and filtering plants. In addition to those controls, general environmental factors are also accounted as a general control and should be treated properly regardless of any other measures taken.

Environmental  factors  are  temperature  and  humidity  and  to  a  lesser  extent  noise  and natural light. When those factors are within their recommended ranges, the occupants are within a “comfort zone”. Otherwise, symptoms of irritation may occur that may mislead the occupants’ attention to air contaminants as the source of their IAP problems.

Environmental comfort zone can be different from summer and winter, following the guidelines set by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 55-2004 Standard:

Table 5: Optimal Environment Comfort Conditions


Summer:  Temperature of 73 to 79°F at 50% RH Winter:     Temperature of 68 to 75°F at 30% RH Air movement < 30 FPM

Vertical temperature gradient < 5°F between 4” and 67” from floor level

Source: (ASHRAE, 2004)

Based on the ASHRAE 55-2004 standard Burroughs and Hansen set the general comfort zone target within 30 to 60 percent of Relative Humidity (RH) and with a temperature from 68°F to 76°F. (23°C to 25°C). (Burroughs & Hansen, 2011)

Besides environmental control, a number of pre-emptive general control measures should be taken:

G0a: The most basic ventilation control which relies totally on outdoor air inflow occurring from natural ventilation mediums such as open windows and open doors and from house infiltration, commonly known as air leakage which is the process of outdoor air entering the house from wall, roof, door leaks and from not adequately insulated material such as thin windows and doors, due to pressure differentials between the outdoor and indoor air.

Older houses, due to less strict energy conservation standards have very high numbers of natural ventilation, especially coming from infiltration, usually ranging between 4 to 9 ACH (Air changes per hour) as compared to 1.5 ACH found energy efficient homes. Typical American homes are around 3 ACH, still way above the ASHRAE’s limit of 0.35 ACH, although that number certainly does not guaranty IAQ security. (Green Compliance, 2011). The selection of systems in this paper tries to exceed ASHRAES lower limitation at least by 3 times.

G0b:  Refers to the most common mechanical ventilation system found in American homes which is local exhaust ventilation. Local exhaust ventilation relies on exhaust fans installed in high air polluting rooms such is the kitchen and the bathroom  that remove the room’s indoor air but without replacing it with the outdoor one. That results in depressurization of the house that increases infiltration air coming in, however the infiltrated air is of less quality then the one brought in from mechanical means from outside.

G0c: Refers to a centralized mechanical ventilation system covering the entire house. It’s usually  implemented  along  with  local  exhaust  ventilation  on  bathrooms  and  kitchens. Central ventilation systems vary greatly in their technologies and their costs, initial and operational. While all centralized ventilations use forced air systems to circulate indoor air throughout the house, because of energy concerns just the minority of them brings fresh outdoor air inside.

New   systems  such  as   ERV  (Energy   Recovery   Ventilation)  and  HRV   (Heat   Recovery Ventilation) counter the previous issue by conditioning fresh outdoor air with the temperature/humidity of the existing indoor air and then diluting it through the house, thus improving IAQ and saving energy costs.

However, the initial installation of ERV and HRV is much higher than conventional forced air systems, but accounting for the reduced operational costs it can become a wiser long run choice.


air purifier Phillips

G1a: This general ventilation upgrades control from G0a by adding air cleaners (class A)9 with VOC capture capabilities to all active bedrooms(bedrooms with daily occupants) to compensate for the absence of a mechanical ventilation system. Additionally a selection of air cleaning plants following NASA’s guidelines to prevent VOC emissions should be implemented10 . (NASA, 1989)

G1b: This general ventilation upgrades control from G0b by adding air cleaners again to all active bedrooms. In this case, class B air cleaners are suggested that have high particulate capture efficiencies but no VOC capturing capabilities.

The reason for avoiding the VOC capability is that it’s a costly option for purifiers, especially in terms of filter changing costs, and in the case of a house already having local exhaust ventilation in place at the high polluting areas, VOC emissions are expected to be relatively low in the rest of the house, including the bedrooms.

G1c: This system calls for two upgrades from G0c. First installing in each bedroom  class C air cleaners that has decent particulate capture rates.11 A higher quality purifier is not needed here since the centralized ventilation should be already providing efficient particulate and gaseous pollutant removal.

Second upgrade is the replacement of the existing filters found on the ventilation system (much commonly around MERV 8-11) with MERV 13-14 filters, as advised  from  several studies for IAQ proactive actions. (Ying, et al., 2010)

G2a: This control calls for the upgrade from G1a by installing a balanced central ventilation system12, with or without ERV/HRV capabilities. The balanced central ventilation should also be supplied with high efficiency MERV15 filters and be properly maintained. Air cleaners should also be periodically maintained.

G2b: This control calls for the upgrade from G1b by implementing the same recommendations as in G2a, which is upgrading to a balanced central ventilation system (w or w/o ERV capabilities) and replacing the current filters to MERV 15. Implementation costs could be less than the G1a upgrade since the already existing local exhaust ductwork may be used to complement the balanced central ventilation duct work.

G2c:  This  control  calls  for  the  upgrade  from  G1c  by  installing  to  the  central  system  a balanced air supply (class B)13  if there is not one already. The balanced central ventilation should also be upgraded with high efficiency MERV15 filters and be properly maintained

G3A: Upgrade from G1a to install a balanced central ventilation system (class A) with high efficiency furnace /fan motors to handle MERV 16+ filters. Costs will be very high including the entire house ducting, the ventilation system itself and its replaceable parts.

G3B: Upgrade from G1b to add to the existing local exhaust ventilation a balanced central ventilation system (class A) with high efficiency furnace /fan motors to handle MERV 16+ filters. Costs will be high but may experience deductions if the existing local exhaust system and ductwork could be utilized.

G3C: Upgrade from G1c central forced air system to a high capacity balanced central one with upgrades to the ductwork and mechanical parts. If the central system is already with balanced air supply then additional ductwork is not needed.

Nonetheless, in both cases, a higher capacity  furnace/fan motors to handle MERV 16+ filters will probably be needed due to the high airflow resistant of the HEPA filters. Costs will be moderate considering the limited (if any) new ductwork and the upgrade of the existing furnace/air motor without the need to a buy a new one

G3 a/b/c: Upgrade the balanced central ventilation systems found on G2a/G2b/G2c (class B) to higher capacity (class A) ones that can handle MERV 16+ filters (HEPA efficiency). Costs will be relatively low since the only upgrades are mostly going to be for increasing the airflow from the furnace/air fans and rarely for fortifying the ductwork.

Monitoring Control

Monitoring control systems are useful to locate pollutant sources when IAQ symptoms are clearly  evident  but  there  is  ambiguity  for their  origin.  Even  though monitoring  systems occasionally may not pin point a single pollutant as the source of the problem, they can still narrow down possible options by excluding those pollutants that were within normal limits. However, due to their relative complexity and costs, they should be used after some basic source and general controls have been applied, with the exception of M1 system, as explained:

M1: Even though the S1 controls suggest that monitoring systems should be taken usually at phase 2 or later, when some symptoms have already occurred, there is one exception to the rule: Radon control. Radon is a radioactive gas that it’s virtually undetectable to human senses and that in high concentrations (usually above 4 pCi/L) can cause devastating long- term effects such as lung cancer. Contrary in short-term periods shows no symptoms at all.

Just in the US,  EPA estimates more than 20 000 yearly deaths directly  linked  to radon exposure (EPA, 2013) . Therefore, it is highly advisable as basic source control measure to buy a radon test kit and test for those concentrations

The Radon Test kits available in the US are very affordable, at about $12 , and many states such as California subsidize them through their Health Departments. The samples are taken by the homeowner and then sent at already covered costs for laboratory results. If t he results show concentrations that average above the 4 pCi/L standard set by EPA, the homeowner should go through a Radon mitigation system until the average indoor concentration reach acceptable limits.

M2: There is a threefold action plan for this measure that takes place after symptoms occur. First, a reliable humidity and temperature monitor is needed to ensure that environmental conditions are not causing symptoms per se but also that are not acting as breeding grounds for other contaminants such is the case with high humidity and mold.

Second, a do-it-your-self CO2 detector tube is needed to see the effectiveness of the various ventilation systems installed. That is achieved in the following manner: C02 is rarely a pollutant  per  se,  but  instead is  a  great  surrogate  for other  pollutants.  Elevated  carbon dioxide concentrations in indoor air as compared to concentrations in outdoor air are an indicator of inadequate/ inefficient ventilation to dilute the indoor air from its pollutants. If such a problem is evident, control measures may be focused on the ventilation systems instead.

Even though different methods were proposed for determining CO2 alert levels, the one proposed by Andrew Persily is one of the most accurate. He proposes that instead of using fixed upper limits of CO2 indoor air concentration levels14, it’s more appropriate to use as trigger limits C02 differentials of more than 700ppm between outdoor and indoor levels. (Percily, 1997)

The  third  and  last  action is  asking  the  homeowner to  use  pollutant  specific, single  use detector tubes to measure contaminants that suspected for causing his IAQ problems. Different providers of friendly-to-use and affordable detector tubes can be found on the appendix.

M3: The last stage of monitoring control is implemented by the professional IAQ team and usually   involves   the   usage   of   very   expensive   monitoring   systems.   However it is unaccustomed for the IAQ expert to ask the homeowner for the purchase of such systems, but rather he charges him for the monitor’s usage and the analysis.

The only occasion that the author of this paper might recommend a professional monitoring system is for a wall mounted C02 NDIR sensor that is used to trigger the central ventilation system on demand15 and thus achieving energy costs along with efficient air quality preservation.

Diagnostic Expert Control

D: When all attempts done by the homeowner to identify or treat the IAQ issue fail, then an air quality expert or team of experts should be called. Even though calling an IAQ specialist is becoming a common practice for workplace environments, for households it is still rare. The reasons for that are twofold. First, most IAQ issues can be treated effectively by relatively little effort by the homeowner. Second, the costs involved in calling an IAQ specialist are usually very high. Diagnosis and treatment is often done by the air specialists for simple IAQ issues, while for more technical issues, a specialized subcontractor is usually called working on behalf of the specialist (usually in ventilation system upgrades and other handwork).

finding pathogens and preventing air pollutionNow that each system used in our research is presented we may move forward to table 6 which shows the corresponding costs for each IAQ control system, distinguishing the initial with the re-occurring annual costs. The re-occurring costs are further dived into 3 subcategories: filter costs that describe all the filter changes done annually according to the manufacturer’s   recommendations;   service   costs   that   could   be either done by the homeowner or professional and last electricity costs calculating annual consumption

Why to improve your air quality?

There are many ways to answer this but we prefer let science explain it. The articles below are here to help you decide.

This scientific study as published by the Ecological Indicators  journal reports that just an “on average, an increase in pollution particles in the air of 10 micrograms per cubic meter cuts victims’ life expectancy by 9-11 years

Another scientific study by the World Health Organization reports that “7 million premature deaths annually linked to air pollution” and that there is a strong link to diseases such as cancer,  strokes, heart disease and others.

Want to find about more studies and guides related to air quality? Here on our blog you can see the latest news in Air Quality, Nose Filters, and Air Filtration.

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