Author: Carlos



The threat to humanity, resulting from an increase in global temperature, has created very sharp divisions in our country. While the majority recognize the present danger, and believe that it has been caused by human activity, others believe that it is just a normal cycle that has occurred many times in the past and that nature will adapt.

But everybody agrees that the cause is an increase in Carbon Dioxide in the atmosphere, creating a greenhouse effect that results in an increase in global temperature. The sharp discussions center on possible solutions.


Replace carbon fuels with alternative energy sources such as solar and wind. However, climate change is a global problem that requires global solutions. Many developing countries have only coal available for their energy needs and can not be expected to eliminate this source of energy completely. There are many ways to limit carbon emissions such as:


– Design more efficient vehicles using natural gas in lieu of gasoline.

– Use advanced technology that can produce “clean” coal.

– Convert power plants from oil to natural gas.

– Sequester carbon emissions at the source of combustion in power plants using electrostatic precipitators.





All the above solutions should be pursued. However, there is one method for removing Carbon Dioxide from the atmosphere that is not controversial and to which we can all agree.

Planting trees is not controversial and is one proven method to remove Carbon Dioxide from the atmosphere. While we continue to improve other methods, reforestation is something we can all support and implement now.


Earth climate is very complex with many factors affecting the Earth temperature. However, basically the earth temperature is determined by a balance between the energy the Earth receives from the sun ( 240 watts/ square meter of Earth surface) and the output from the Earth from radiation ( which is proportional to the fourth power of the Earth surface temperature). If the radiation from Earth would be allowed to escape, then the balance of input and output would result in an Earth temperature of about 0 Degrees Fahrenheit. However, some of the radiation leaving the Earth is reflected back to Earth by certain gases in the atmosphere ( Carbon Dioxide, methane and water vapor). This reflected radiation elevates the Earth temperature. In the past, prior to the Industrial Revolution, the “normal” amount of Carbon Dioxide in the atmosphere, which reflected some radiation to Earth, resulted in a balance of temperature at about 60 Degrees Fahrenheit. This increase of temperature is what makes our planet habitable.” Normal” greenhouse is a good thing ! [5]



Our problem is that the additional Carbon emissions generated by human activities, continue to grow, and as a result, continue to increase the Earth’s surface temperature.

Another factor to consider is the so called atmospheric carbon cycle. The carbon in the atmosphere is constantly exchanging amounts with the carbon dissolved in the ocean water and the carbon present on land. The total carbon content in the atmosphere is approximately 720 gigatons ( one gigaton, Gt. is one billion metric tonnes).

The ocean carbon reservoir is about 39,000 Gt. The land carbon reservoir is about 2000 Gt ( 1500 Gt in the soil and 500 Gt in plants).

The exchange of carbon from the atmosphere with the carbon in the ocean is more or less in balance. About 90 Gt of carbon, in the form of carbon dioxide, are dissolved yearly in the ocean water. This amount, removed from the atmosphere, is balanced by the amount of carbon dioxide that escapes the ocean water, which is about 88 Gt. There is more or less a balance, although the amount exchanged varies with water temperature and ocean currents.

The exchange of atmospheric carbon with land carbon is something we can affect. The photosynthesis of plants remove 110 Gt of carbon yearly, while animal carbon dioxide from respiration and waste decay add about the same amount to the atmosphere. Adding plants would increase the amount of carbon removed from the atmosphere.

We can reduce carbon dioxide emissions by reducing combustion of carbon fuels. This is the main contributor to carbon emissions. We must do this. However, the next largest source of carbon dioxide emissions is from deforestation and land use. That is why scientists recommend carbon dioxide sequestration, by increasing afforestation (restoring trees in areas deforested many years ago) and reforestation ( replacing trees recently removed from existing forests ). Planting in these priority areas will provide the greatest benefits because they are proven locations that do not require water irrigation in addition to the normal rainfall in that location. Reversing deforestation has the added benefit of saving the habitat of many endangered species and protecting biodiversity.


The importance of reversing global deforestation has been known for many years. Many scientific papers have been written examining where trees should be planted and what type. Fortunately the interest in the subject is accelerating and many new projects are being started.

For example in Europe we have seen a forest boom. Between 1990 and 2015, the area covered by forests and woodlands has increased by 90,000 square kilometers [1]. In November 2006, the United Nations launched the United Nations Environment Programme (UNEP) Billion Tree Campaign. According to the UNEP trees are the most effective and cheapest means of binding carbon dioxide, so the more trees there are growing on Earth, the better we can hope to mitigate the climate crisis.[2]

In 2011, the UNEP handed over the management of the Billion Tree Campaign to the Plant for the Planet Foundation which plants trees in the Mexico Yucatan Peninsula and has now grown to the Trillion Tree campaign, active in 73 countries.

Other organizations promoting reforestation are:

– ( including American ReLeaf, Forest-Climate Working Group (FCWG), U.S. Climate Alliance ) [4]

– the Canopy Project, part of the Earth Day Network. ( The Earth day Network has a goal of planting 7.8 billion trees in 2020)

Individual countries are also starting projects around the Globe.

On June 22, 2013, Pakistan’s Sindh Forest Department set a Guinness World Record when 300 people planted 847,275 trees in 24 hours [3].

On July 11,2016, India eclipsed that record by planting 49.3 million tree saplings.

On July 29,2019,, Ethiopia mobilized a vast number of volunteers across the country to plant millions of trees as part of the Government’s “Green Legacy Initiative”. This initiative has a goal of planting 4 billion trees between May and October in the rainy season.

In 2015, 10 African countries launched the African Forest Landscape Restoration Initiative, which aims to restore 386,000 square miles of the continent’s land by 2030. [3]

Most recently the World Economic Forum in Davos, Switzerland, launched the project to unite governments and businesses in a mass scale nature restoration that will restore and conserve 1 trillion trees around the world. In this Davos meeting the USA president Donald Trump (an earlier climate change skeptic) , committed the USA to this project.


There is hope. Reforestation projects are now being implemented across the Globe. The World Economic Forum also acknowledged the work of existing reforestation programs and pledged to help join all of these initiatives in a coordinated and global effort. According to the Forum, locking up carbon in the world’s forests can provide up to one third of the emissions reductions required by 2030 to meet the Paris climate agreement targets.


Save the planet but start with clean indoor air so you can stay healthy for the cause. Click here to find out how you can improve your indoor air quality.







Dirty Air in the Office – Fix it Now with Desktop Air Purifiers

I have written before on the health risks associated with unhealthy air in our homes and how to improve indoor air quality. However, many of us spend considerable time outside our homes in our offices at work. Our work place may not have adequate air quality. In particular, scientists tell us that office equipment such as printers, fax machines and computers generate Volatile Organic Compounds (VOC)s which may not be removed by the office air conditioning system.

Furthermore, since office machines are in close proximity to the people who use these machines, both at home and in offices, their effect on health requires urgent examination.

What the Scientists tell us

Laboratory tests have detected the following harmful emissions emanating from common office equipment:

Toluene, Styrene, Benzene,Chloroform and Metyl Chloride. In addition, the ozone emitted by printers can combine with other VOCs in the room and produce harmful secondary pollutants and ultrafine aerosol particles [1]. These tests also showed that emissions from laser printers were higher than those from ink-jet printers [2].

To address this air pollution created indoors it is recommended that cool and dry clean air be introduced close to the breathing zone of each individual [3].

To comply with this recommendation it is advisable that we keep on our desk a small air purifier that will protect our personal environment. This small air purifier, suitable for areas 50 to 150 square feet, does not have to be expensive. Many low cost small air purifiers are available in the market.

Desktop Air Purifiers

To select a suitable Desktop Air Purifier we must evaluate the quality of each of the main elements of the Air Purifier.

– Pre-Filter

– Main Filter

– Carbon Activated Filter

– UFC Light (optional)


Particulate matter (PM) air pollution is an air suspended mixture of solid and liquid particles of various sizes. Scientists classify the particles in 3 categories.

Coarse Particles – larger than 2.5 micrometer ( PM10) . Examples: dust, pollen, mold,spores,pet dander

Fine Particles – smaller than 2.5 micrometer ( PM2.5) . Examples: VOCs such as benzene, toluene and formaldehyde from smoking, cooking on gas stoves, cleaning fluids, solvents and pesticides.

Ultrafine Particles – smaller than 0.1 micrometer (included in the PM2.5 classification) Examples: vehicle exhaust gases, gases from atmospheric photochemical reactions, viruses.

The majority of the particles present in our homes or offices are large particles. These large particles can clog the main filter in the air purifier reducing its efficiency for capturing the smaller, more dangerous particles.

Therefore, it is very important that the air purifiers include a pre-filter to remove the large particles. The pre-filter should be easily removed so that it can be cleaned or replaced regularly. This will insure efficient operation of the Air Purifier.


There are mainly two types of filters for particle collection.

– Electrostatic Precipitation Filters (ESP)

ESP’s use a high voltage wire to charge incoming particles which are then collected on charged plates inside the air cleaner. These units are mostly installed in whole house ventilation systems. We will not examine this type of filters in this article, which is aimed only at Desktop Air Purifiers.

– Fibrous Media Filters

Within this category we recommend the High Efficienct Particulate Air (HEPA) Filters. These filters are manufactured as flat pleated sheets of different thicknesses. As the air is forced through the filter the particulates are attracted and get attached to the HEPA filter fibers. The HEPA filters offer the highest available particle removal efficiency of fibrous media filters. They usually have a removal efficiency of 99% or higher. There are two methods for evaluating fibrous media filters.

a ) Efficiency Testing

The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHREA) in their standard 52.2 specify a testing method. This method measures the removal efficiency of particles sizes 0.3 to 10 micrometers in diameter. The test results are reported as Minimum Efficiency Reporting Value (MERV) numbers ranging from MERV 1 to Merv 16. The rating numbers are based on the average removal efficiency for 3 particles sizes in ranges .3 to 1 micrometers, 1 to 3 micrometers, and 3 to 10 micrometers. The better the filter the higher the MERV number. The test method is very specific.

Filters with a MERV 13 rating must remove at least 50% of the 0.3 to 1 micrometer particles. This size of particles are the most harmful of human health. The HEPA filters are equivalent to MERV 16. Many filter manufacturers display the MERV number on their filter packaging.

b ) Clean Air Flow through the Filter

When the filters are installed in a portable Air Purifier the efficiency of the Air Purifier and Filter is measured in units of Clean Air Delivery Rate (CADR). This is a measure of the Air Purifier delivery of relatively clean air, expressed in cubic feet per minute (cfm).

In comparing different Desktop Air Purifiers we should compare their HEPA filter and their CADR ratings.


Carbon Activated Filters are an additional filter that is incorporated in the best Desktop Air Purifiers to adsorb odors from pets, smoking and cooking. In some Air Purifiers the carbon activated filter is combined with the pre-filter.


A UFC lamp is an ultraviolet germicidal lamp with a wavelength of 200 to 300 nanometers (nm) used to destroy germs and viruses. The UFC light has been shown to kill airborne germs including staph, influenza and pneumonia. One of the recommended Desktop Air Purifiers incorporates a photocatalyst TiO2 activated by the UFC light and combined with an activated carbon filter. This combination is reported to increase the pollutant removal efficiency and also to reduce the amount of secondary VOCs [4].

Although many scientists believe that UVC rays are not harmful to humans, there are others who differ from this opinion. It is possible to select a Desktop Air Purifier that includes an UFC lamp but the lamp can be turned off. So use of the UFC lamp can be optional. Or it could be used during business off hours when people are not present.

Comparison of 3 Excellent Desktop Air Purifiers





We must take the steps necessary to ensure that our environment is healthy. Clean indoor air is our individual responsibility, at home or in the office. I encourage you to look into Desktop Air Purifiers to improve your personal environment.

For details on the Air Purifier I recommend click here


[1] Hugo Destaillats et al. “Indoor pollutants emitted by office equipment”.A review of reported data and information needs. Lawrence Berkeley National Laboratory, Environmental Energy Technologies Division.January 2007,LBNL-62082

[2] S.C.Lee,Sanches Lam,Ho Kin Fai.” Characterization of VOCs,ozone,and PM10 emissions from office equipment in an environmental chamber”.Department of Civil and Structural Engineering, The Hong Kong Polytyechnic University,Hong Kong. Building and Environment 36(2001)837-842

[3] P.Ole Fanger. “Indoor Air Quality in the 21st. Century Search for Excellence”. Indoor Air/Volume 10, Issue 2,December 2001. Study from the Technical University of Denmark.

[4] C.H.Ao,S.C.Lee. ” Indoor air purification by photocatalyst TiO2 immobilized on an activated carbon filter installed in an air cleaner.” Department of Civil and Structural Engineering.The Hong Kong Polytechnic University.Chemical Engineering Science. 60(2005)103-109


Improving Indoor Air Quality – Getting Ready for Spring

Getting Ready for Spring

We all look forward to the warm weather, clear skies and spring flowers. We can once again open windows in the morning and late evening, letting fresh air in, thus providing adequate ventilation.

But spring also brings an increase in mold and allergens like pollen from outside air. Furthermore, we will be spending more time outdoors so we will be exposed to these allergens. It is important therefore, that the time we spend indoors is in a clean and healthy environment.

What Scientists tell us about Spring Health Risks

In addition to pollen and mold spores, springtime also brings less known dangers. A report by Daniel Jaffe, et al., published in the Geophysical Research Letters [1] shows that during spring there is an increase of background levels of ozone on the west coast of North America. This report shows that ozone in air arriving from the Eastern Pacific in the spring has increased by approximately 30% from the mid 1980s to the present

The elevated levels of ozone are a concern since when combined with small particles in the air, PM2.5, they affect the respiratory system. A Study of the Effects of Low-Level Ozone and Fine Particles on the Respiratory Symptoms in Children with Asthma by Janneane F. Gent et al.., published by the American Medical Association [2], concludes that simultaneous exposure to ozone and fine particles contribute to increase respiratory symptoms and the need for rescue medication use.

It is also known that Mold Allergy problems increase in the spring. Furthermore, studies show that risk of death from asthma during the pollen season is related to the level of Environmental Molds [3]. All the above risks suggest that we should remain vigilant and minimize indoor air pollution. Indoor Air Quality in our homes is our individual responsibility.

What should we do to insure Healthy Indoor Air in the Spring ?

We have discussed in other articles [4] that the science of clean air is still evolving. There is no scientific consensus on what constitutes “clean air “. Most of the standards are based on “perceived air quality”. Perceived Air Quality (PAQ) is the statistical average of the subjective assessments of air quality by those living in a home or working in a business environment.

Nevertheless, there are common sense actions we can take to improve our Indoor Air Quality (IAQ).

Eliminate Fine Particles (PM2.5) from indoor air

PM2.5 particles are those smaller than 2.5 micrometers. It is especially important to eliminate the ultra fine particles (smaller than .1 micrometers) since these ultra fine particles can translate from lungs to the blood system.Note: Definition of these particles and a discussion of the health risks posed by indoor air pollution can be found in Reference [5].

Do Not Smoke Indoors

Eliminate Volatile Organic Compounds (VOC’s)

These include fragrances, formaldehyde and other emissions from building materials and furniture. According to a Danish Building Standard the amount of VOC’s should be below levels that can be sensed by the occupants.

Monitor Carbon Dioxide (CO2)

Carbon Dioxide levels to be kept below 1000ppm. Must have Carbon Monoxide detectors since malfunctioning furnaces can be lethal.


Homes should be ventilated as a minimum at a rate of 7.5 cfm(cubic feet per minute) per person plus 3 cfm per 100 square feet of home size. Standards assume that number of home occupants will be equal to the number of bedrooms plus one. As an example a 2000 square feet home, with 2 bedrooms, would require a minimum of 82.5 cfm. [6]


Humidity should be approximately 35% RH in winter months and 50% RH in the summer.

Air Filters

Air Filters in the Air Conditioning System should be checked and replaced regularly. The Air Filters used should have a Minimum Efficiency Reporting Value (MERV) of 13. This quality filters remove at least 50% of the o.3- 1 micrometer particles.(These are the particle sizes that are most harmful to human health). The best filters, however, are the High Efficiency Particulate Air (HEPA) Filters. These filters are equivalent to a MERV 16 and remove 99% of particles. [7]

Air Purifiers

European Standards recommend that air should be supplied to the occupants cool and dry. In addition, the clean air should be introduced close to the breathing zone of each individual. Air Purifiers in the proximity of the occupants should be used. Or at least in the kitchen, living room and bedrooms where many of the indoor pollutants originate.[8]


Implementing the above recommendations will result in Clean and Healthy Indoor Air in all seasons.

Remember,Indoor Air Quality in our homes is our individual responsibility.



[1] Daniel Jaffe, et al.., Increasing background ozone during spring on the west coast of North America, Geophysical Research Letters / Volume 30, Issue 12

[2] Janneane F. Gent et al.., Association of Low-Level Ozone and Fine Particles With Respiratory Symptoms in Children with Asthma, American Medical Association, JAMA, October 8, 2003- Vol 290, No.14

[3] Paul V.Targonski, et al..,Effect of environmental molds on risk of death from asthma during the pollen season, The Journal of Allergy and Clinical Immunology, Volume 95, Issue 5,Pages 955-961






Improving Indoor Air Quality – Can Green Products Help?


We know that, since we spend 90% of our time indoors, reducing indoor air pollution is essential for a healthy environment in our homes. Some indoor air pollution comes as infiltration from outside, but we create a large percentage of the pollution through our daily activities. So the question is, can we minimize the pollution that we create by using “green products”. In this post we will examine this question and discuss our options.


Not much. Most scientific papers deal with specific contaminants and how they can be studied in a laboratory situation. Most papers are written by scientists for scientists or to get recognition by their peers. The individual papers do not shed light on the broad picture of healthy indoor environment. After reviewing tens of papers I could not find one with actionable information. Even if contaminants are identified the amount or concentration that should not be exceeded to avoid damage to our health is not defined. Furthermore, the cumulative effect of the presence of several contaminants is not studied.


However, some general reviews of literature on semi-volatile organic compounds (SVOCs) in the indoor environment present useful information [1]. The top five indoor exposure agents are combustion particles, bio aerosols, radon, carbon monoxide and volatile organic compounds (VOCs). In addition, there are also present semi-volatile organic compounds (SVOCs) that are emitted from consumer products that we find in our home environment. Unfortunately most of the studies show a lack of data on concentrations of chemicals in consumer products. So it is not possible to link their presence to health issues. These chemicals are present in carpets and textiles, furniture, building materials, flooring, cleaning products, health/personal care products and cosmetics.


Green products are products that have less impact on the environment or are less detrimental to human health than the equivalent traditional products. In general, they are energy efficient, free of toxic chemicals and require less earth resources to produce. Green products are also referred as sustainable and earth friendly. As they apply to indoor air quality the most important are the cleaning products, because it is easy to substitute green cleaning products for their toxic equivalent. Green cleaning products are desirable because they reduce our exposure to chemicals indoors. However, their use will not guarantee a healthy environment since they represent only a small percentage of the total VOCs emitted indoors. Therefore, we should use green cleaning products as much as possible, but they are not a substitute for Air Cleaners.


There is no scientific evidence that using “green” consumer products will improve indoor air quality and create a healthy indoor environment. Because new products are constantly introduced to our home environment, many of which include “additives” with unknown or undisclosed chemicals, it is very difficult to know if our environment is healthy.

Common sense dictates that we avoid using sprays and fragrances and that we provide adequate ventilation. Other than that, as insurance, it is a good idea to use Air Cleaners in rooms where indoor air pollution is created such as kitchen and bedrooms.


Indoor Air – Comfortable or Healthy?


The science correlating clean air with health issues is still evolving. There is no standard definition of “Clean Air”. As a result, most standards for building indoor air quality (IAQ) are established based on people’s perception of air quality. In this article we will examine both perceived air quality and actual clean air. We will present our conclusion and recommendations for achieving the healthiest indoor air possible.

Comfortable Air

Perceived Air Quality (PAQ), as the name indicates, is the subjective assessment of air quality by those living in a home or working in a business environment. Home builders want to build homes that meet the wishes of the occupants. To determine what standards must be achieved to that end the builders conduct field studies in which sample subjects are exposed to different environment conditions, and their satisfaction with that environment is recorded.

A typical study [1] varied three levels of air temperature and humidity and two levels of ventilation rate. The values for temperature and relative humidity were:

20 Degrees C/ 40% RH, 23 Degrees C/ 50% RH,26 Degrees C/ 60%RH

Ventilation in these tests was set as:

10 liters/ second per person

3.5 liters/ second per person

Other studies [2] have examined the effect of CO2 on air perception quality.


These studies show that there is not a single value for the parameters studied that would assure an acceptable perceived air quality. The studies only show that air is perceived as acceptable when it is cool and dry and unacceptable when it is warm and humid. The ideal conditions depend on your geographical location and time of the year. Ideal Humidity is between 30% RH and 50% RH. For example Canadian standards recommend 35% RH in winter and 50% RH in summer

Other recommended values are CO2 less than 1000 ppm and ventilation rate above 0.5 air change rate per hour( or 14 liters/sec per person).

Other factors are also considered for improving comfort. For example a Danish labeling system for building primary emissions of volatile organic compounds (VOC) [3] focuses on comfort by minimizing annoying odors and mucous membrane irritation. The values of the VOCs should be below levels that can be sensed by the occupants. These levels have nothing to do with health impact. As we can see the emphasis is on maximizing the air quality perception, not the health of the building occupant.

Healthy Air

The science of clean air is still evolving. There is no standard definition of “clean air”. Scientific studies have focused on specific issues related to the ambient air such as the effects of radon, formaldehyde, sick building syndrome, air particulates, VOCs and ventilation. But all these studies were focused on the specific problems noted above. There is no single science branch that addresses all the above factors together as one subject. However, there is mounting evidence of the importance of indoor air pollution and lack of adequate ventilation in establishing a healthy air environment.Getting an Air Quality Monitor for your home is a good first step to improve your indoor air quality. Continue reading “Indoor Air – Comfortable or Healthy?”


Winter Months Challenge

Winter is almost here and new challenges to clean indoor air are upon us now. In spring and summer we worry about outdoor allergens like pollen and also about pollution created indoors from cooking, and smoking, and VOC’s. Air conditioning keeps us comfortably cool in the noon and afternoon hours. Opening windows in the morning or late evening to let fresh air in insures that we have fresh outdoor air and meets the recommended ventilation rates. Air purifiers add another level of insurance.

But in the winter months’ ventilation is more difficult. We tend to seal the home tighter, add insulation to windows and doors to prevent heat losses and reduce heating costs. But these actions create new problems.

Lack of adequate ventilation allows pollutants to accumulate inside the house and operating furnaces add to the level of CO2 and even increase the risk of carbon monoxide poisoning.

We have to be more vigilant. Also, the holiday season with the added fragrances, to make the home smell “nice”, add to the problem with the increased emission of VOC’s.Click here to see my recommendation on a very efficient HVAC filter.

Importance of Ventilation

Ventilation is still necessary, we must expel the stale air and allow the intake of fresh air. Ideally we should have installed a heat recovery ventilator (HRV) that extracts heat from the stale air that is exhausted from the house and transfers it to the incoming fresh, but cold, air. It is a heat exchanger where the exhaust air warms up the incoming supply air. These systems may be expensive to install but will provide energy savings since the furnace will cycle on less frequently. However, even if you do not have an HRV in your home you still must have ventilation.

But I want to stress that you must have CO, carbon monoxide, detectors in your home since malfunctioning furnaces can be lethal. Continue reading “IMPROVING INDOOR AIR QUALITY – WINTER MONTHS CHALLENGE”




In previous articles we have discussed the health risks of indoor pollution, the need for adequate ventilation and the desirability of having air quality monitors and air purifiers in our homes. However these benefits are only obtained if we have regular maintenance of our air cleaning equipment and air conditioning units. And most important is the use of correct air filters.


Types of Air Filters

There are mainly two types of air filters for particle collection.

– Fibrous Media Filters

There are two methods for evaluating this type of filter.                                                                                                             a) Test Method specified in The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) Standard 52.2. This method evaluates the removal efficiency for particle sizes 0.3 to 10 µm in diameter. The results are reported as Minimum Efficiency Reporting Value (MERV).MERV numbers range from MERV 1 to MERV 16,based on average removing efficiency across 3 particle sizes in ranges 0.3 -1 µm, 1 – 3 µm, and 3- 10 µm. The higher the filter rating the higher the filter’s removal of particles efficiency. Filters with a MERV 13 and above ratings require at least 50 % removal efficiency for 0.3 – 1 µm particles (These are the size of particles that are the most harmful to human health). MERV 11 filters must achieve at least 20 % removal of these particles. The Environmental Protection Agency (EPA) recommends furnace filters with at least MERV 13 rating [1]. High Efficiency Particulate Air (HEPA) filters are generally equivalent to MERV 16 and offer the highest available particle removal efficiency of fibrous media air filters. Usually with a removal efficiency of 99 % or higher. Click here to see details on my recommendation for a very efficient HVAC air filter.

b) When the air filters are used in a portable air cleaning unit, the filter’s efficiency is measured by the unit’s Clean Air Delivery Rate (CADR). The CADR is a measure of a portable air cleaner’s delivery of relatively clean air, expressed in cubic feet per minute (cfm) Continue reading “AIR FILTERS”




Politicians are proposing or implementing Cap and Trade policies with the intended goal of reducing Greenhouse Gas (GHG) emissions. This a worthwhile goal that we should all support. However, when legislators and attorneys write the rules of Cap and Trade the process becomes unnecessarily complicated. The basic premise of Cap and Trade is that Companies that exceed GHG emission standards should pay a penalty or purchase an allowance for polluting from Companies that do not pollute. It is claimed that this process will encourage the polluters to not pollute in order to cut costs. In this paper we propose that money from penalties assessed under Cap and Trade policies be used to help CO2 sequestration through reforestation in locations recommended by the scientists.









To study the effects of GHG emissions we need to look first at the magnitude of the problem and then review possible solutions. A brief summary of the facts follows. Continue reading “CAP AND TRADE POLICIES”





Adequate ventilation is a key factor in achieving indoor air quality (IAQ).Our goal is to remove particulates and VOCs from our indoor environment. We can achieve this goal through ventilation, through portable air cleaners or a combination of both. The proper balance between the two will depend on our specific situation.

A brand new home will have been designed to meet local building standards, which in most places specify ventilation requirements. Since new buildings are designed mostly for energy savings they are typically built to minimize energy losses and are therefore tightly insulated, minimizing air infiltration. But new buildings make use of synthetic materials that introduce new contaminants such as volatile organic compounds (VOC) s.

So, if you have a brand new home you cannot assume that you have good indoor air quality. On the other hand, if you live in an older home you probably have a large outside air infiltration. Depending on your location, this air infiltration may carry pollutants which you must remove along with the pollutants created indoors from normal living. Furthermore, your older air ventilation system, if any, may not be adequate.

In this article we will examine common sense approaches for improving indoor air quality. Continue reading “VENTILATION- HOW MUCH IS NECESSARY?”

Air Quality Monitors -Do You Need One ?



Indoor air quality monitors have improved significantly in the last few years. Advances in sensor and computing technologies have allowed the development of low cost air quality monitors that are portable and small in size and capable of being wirelessly connected to smart phones for real time monitoring and reporting the air quality in a room.

The explosion of new models has resulted in over-choice for the consumer. The recent models are designed to monitor some or all of the following air quality parameters.

  • Carbon monoxide (CO)
  • Carbon dioxide (CO2)
  • Volatile organic compounds (VOC)s
  • Particulate Matter (PM)
  • Air turnover
  • Humidity
  • Temperature

Different Air Quality Monitors are designed for specific ambient conditions. All of the above parameters affect our perception of what is a comfortable home. However, not all of these parameters are equally important for a healthy environment.


Most low cost monitors check the amount of CO2 .Scientists have established standards for safe levels of CO2 in an indoor environment. Since all humans exhale CO2 at the same predictable rate, the amount of measured CO2 in the building is used as an indirect measure of human bio-effluent concentration and building occupancy. Building code standards in the USA typically allow for a concentration of CO2 of 1000 ppm. So the amount of CO2 in the ambient air can be used as a way to control air quality. Some of the monitors can be connected to the home ventilation system so that when an unacceptable level of CO2 is reached the ventilation can start automatically.

This first step in monitoring ambient air is good, but it is not sufficient. Scientists have determined that small particulates, PM2.5 (smaller than 2.5 microns) are the most harmful to human health. These particulates can easily penetrate into our lungs and travel into our blood system. They can also transport toxic chemicals. Ensuring a healthy environment requires that we eliminate the PM2.5 particulates from the ambient air. So we should select an Indoor Air Quality Monitor that as a minimum allows us to monitor CO2, PM2.5 particulates and VOCs. (The VOCs are ultrafine particles, smaller than 0.1µm, and included therefore with the PM2.5)

The other parameters are of interest and important if we want to optimize comfort, but are not critical to our health.


Basic Models

These models give you a binary indication of air quality. Either Good or Bad. This indication could be in the form of a digital display or a color code, such as Blue for good, Orange for bad. It is a simple display of air quality but it is not a quantitative measure of the degree of pollution that is present. This type of Air Quality Monitor does not provide any details on the type of pollutant, nor what action should be taken by the user to correct the problem.

Models with Advanced Features

In addition to providing a binary status of the air quality conditions these models have additional features that allow you to find details. Visualization is most important .When combined with data logging, the users can see a chart or display showing the status of each parameter in near real time. The parameters displayed vary with different models.

It has been found that visualizing the problem allows the user to correlate the reading with an on-going activity, thus identifying what actions (cooking, cleaning, smoking, etc.) are causing the increase in indoor pollution.

Furthermore, awareness of the air quality associated with a specific activity promotes behavioral changes that will result in improved air quality in the future.

For those users interested in a better understanding of their pollution problem there are Indoor Air Quality Monitors that have wireless Wi-Fi connection that allows them to access web applications offered by the manufacturer. These apps allow the users to study the trend of measurements as they correlate to time of day, seasons, or other variables. These advanced models are intended for those users technical savvy, or professionals in the field of Building Science that study the interaction of Insulation, Air Conditioning, Ventilation and Air Quality.

Monitoring Systems

The models described above provide detailed information on indoor pollution. However, they do not help you to take action to correct an unhealthy air quality condition. The monitoring systems allow you to integrate the monitor with other home systems. This integration can be achieved through recipes or instructions available from (If This Then That).These instructions may allow you to connect a monitor to a smart thermostat, such as a Nest or an Ecobee thermostat, installed in an Air Conditioning unit or in an Air Purifier. If this connection is made, then the Air Quality Monitor can start automatically the Air Conditioning unit or the Air Purifier if the pollution level warrants it.Please note that not all monitors are designed to allow this integration.

A more advanced integration can be achieved using IoT (The Internet of Things) integration.This is a system being developed by many large companies,such as Microsoft and Amazon,which allows connectivity between all appliances or equipment used in home automation. I would suggest that this more advanced automation is best left to professional Home Systems specialists.


Improving Indoor Air Quality in our home is our individual responsibility.A suitable Air Quality Monitor can provide a good starting point.This is my recommendation on an Air Quality Monitor.

Choose wisely !