Category: Ventilation





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?”


What the Scientists tell us

There is considerable research in academia on ambient air quality. However, ambient refers to outdoor air. Most of the research consists of statistical analysis of hospital admissions for respiratory problems or mortality rates on days when there is extreme air pollution.

The statistical analysis consists of what scientists call meta-analyses (systematic reviews) of single-city time series studies. Basically an average of multiple studies.

The only indoor air studies are those that investigate the effects of indoor open fire cooking.These are important studies, mostly by the World Health Organization (WHO), but they only apply to underdeveloped countries where these practices are unfortunately still prevalent. They are not relevant to indoor conditions in the modern world.

Scientists are still divided on what standards should be imposed on ambient air. The U.S. Environmental Protection Agency (EPA) promulgated the National Ambient Air Quality Standards (NAAQS) designed to establish regulation of fine particulate pollution. But other scientists believe that these standards are too lax, with allowable pollution levels above the standards of the World Health Organization (WHO).

The science of clean air is not settled.

The statistical studies of ambient air have, however, one important conclusion. They tell us that the pollution effect on human health depends in part on the size of the particles in the air.

In this case size matters.

We can use this information when we address indoor pollution solutions.

But improving indoor air quality in our homes is our individual responsibility.

We cannot wait for solutions from the academic world. Continue reading “INDOOR AIR POLLUTION -WHAT ARE THE HEALTH RISKS”

Green Buildings and Indoor Air Quality – Energy Efficiency or Clean Air?

Building Construction Industry

The construction industry has made great strides in improving building construction.

New building codes and credits for Green Buildings have resulted in more energy efficient buildings and the use of recyclable materials for greater sustainability.

However these advances have not necessarily improved the indoor air quality (IAQ). Modern homes and offices are frequently more airtight than older structures resulting in reduced exchanges between outdoor fresh air and indoor air.

Furthermore, modern buildings make greater use of synthetic building materials that have introduced new contaminants such as volatile organic compounds (VOC), which arise from sources such as paints, varnishes, solvents and preservatives.

The combination of reduced ventilation and the increase in volatile compounds has the potential for a buildup of toxic substances in the home environment.

In the USA as in many other countries, no federal law specifically regulates IAQ, even though people typically spend more than 90% of their time indoors.

Pollutant levels are typically several times to several hundred times higher indoors than outdoors, and consequently indoor air typically accounts for over 90% of human exposure to pollutants.

Building Certification Programs

Green Building Certification programs have increased globally with over 145,000 green certification projects concluded as of 2016 and are forecast to grow by 37% by the end of 2018.The European Union Directive of Energy Performance of Buildings foresees that by the end of 2020 all new buildings should comply with the goal of nearly zero energy performance.[1]

The major Green Building Certification Programs include the Building Research Establishment Environmental Assessment Methodology (BREAM) in the United Kingdom and the Leadership in Energy and Environmental Design (LEED) in the USA. These programs are used in multiple countries around the world. Other significant programs are the Comprehensive Assessment System for Built Environment Efficiency (CASBEE) in Japan and recently (2016) the Deutsche Gesellschaft für nachhaltiges Bauen (DGNB) system in Germany. However there is no standard criteria that is used universally to define a Green Building. Different systems emphasize different Building characteristics.

But these projects, which give credits to builders for compliance, emphasize efficient use of resources (e.g., energy, water and materials) and sustainability.

But not much incentive is given for improving  Indoor Air Quality (IAQ).A recent study found that credits for IAQ accounted for only about 3 to 11% of the total credits.

This relative small percentage of credits for IAQ may be seen as inadequate incentive to pursue these credits.

Green Buildings and Health

Updates to the early Green Building Certification Systems now provide more weight to IAQ. Furthermore, other programs such as the WELL Building Standards [2] are focused specifically on IAQ. Typically Green Building Certifications have different requirements or Categories that need to be met in order to get the Certification. Some of the requirements address Pollution Source Control, Ventilation, and limits for specific pollutants such as formaldehyde, CO2, Volatile Organic Compounds (VOC) s. In addition they may require IAQ measurements. But the majority of requirements emphasize energy savings, water usage, building air tightness, minimize environmental disruption, and sustainability.

Many certificate programs allow “trading” of credits between categories. It may be possible to obtain Green Building Certification without complying with any IAQ requirements. One program, the German DGNB, is the exception in that it does not allow credit trading. Some compliance in each category must be achieved to get their Certification.

One problem that undermines improvements in the levels of IAQ in Green Buildings is that there is no consensus on what good IAQ is, or what factors affect the health of the occupants. Another problem is that some of the “green practices” used in the construction of Green Buildings have negative effects on the IAQ. In example using recycled materials may introduce in the building pollutants or toxic chemicals originated in the recycling process. Another example is the required use of green cleaning products for building maintenance. Many of the so called green cleaning products do not list all of their ingredients and may include fragrances. Fragrances are chemical additives that are dangerous pollutants that, when combined with ozone, can create secondary pollutants that have been proven to affect the health because of their microscopic particles that easily penetrate the respiratory system. In fact the US Centers for Disease Control and Prevention, Indoor Environmental Quality Policy states: “Scented or fragranced products are prohibited at all times in all interior space owned, rented, or leased by CDC”  [3]. Green Buildings have the potential to be beneficial to Health. However, we are not there yet. Progress is slow. It is up to us to control the pollution generated in our homes and to insure that we have adequate ventilation.[4]


It is my conclusion that we cannot rely on government programs to improve IAQ.

Improving indoor air quality of our homes is our individual responsibility.

Adding an Air Purifier can be part of our plan of action.

Click here to find out how you can check the air quality in your home.


[1] Anne Steinemann et al. Ten Questions concerning Green Buildings and indoor air quality.Building and Environment 112 (2017) 351-358

[2] WELL,The International Well Building Institute.The WELL Building Standard,V 1.0,Delos Living LLC,New York,, NY.,2015

[3] CDC,US Centers for Disease Control and Prevention. Indoor Environmental Quality Policy,2009,pp.9-10