healthy house institute

4 Free HHI Books:

Creating a Healthy Household, The Healthy House Answer Book, Healthy Home Building, The Healthy House 4th Edition
Your email will only be used as described in our Privacy Policy

Follow us on Twitter



Proud Supporter of:




Healthy Home Basics - Why are Houses Unhealthy?

By HHI Staff

From The Healthy House Answer Book: Answers to the 133 most commonly asked questions. Questions 1-10.


article continues below ↓

We do not strictly control Google ad content. If you believe any Google ad is inappropriate, please email us directly here.

1. Have houses always been unhealthy or this something new?


Over the centuries, many houses have been unhealthy due to mold, wood smoke, gas lighting, kerosene heaters, coal dust, pests, animal dander, lead pipes, lead paint, asbestos, etc. While some of these pollutants are less common today, we now have new pollutants such as formaldehyde with which to contend. So, although unhealthy houses have been around for a while, the specific pollutants are changing.


2. With all the new environmental laws and regulations, why aren’t houses healthier than ever before?


In some areas, there definitely has been some progress. For example, we no longer use lead paint or asbestos insulation. But in many instances, we’re creating new building products and developing new construction practices faster than they can be evaluated or regulated. Today’s indoor environmental pollution problems are related to two trends—the use of unhealthy materials and unhealthy techniques.


3. What are the two trends that are contributing to make today’s houses unhealthy?


First of all, we’re now building houses tighter for greater energy efficiency, but without mechanical ventilation systems. And second, we’re filling these tighter houses with synthetic, man-made building materials, furnishings, and cleaning products—many of which release pollutants into the air. So, we end up with pollution-filled houses that don’t have enough fresh air. The result is often ill health.


4. How bad is the air in a typical home?


According to many studies, the air inside most houses is 5 to 10 times worse than the outdoor air. And it doesn’t matter where you live—in a major city, or in a rural area—the air is almost always worse indoors. If you measure individual pollutants, some are a whopping 100 times worse indoors.


5. What are the types of contaminants that are often found indoors?


We usually put them into six categories:


•Biologicals (pollutants that are, or once were, alive or are associated with living things) such as mold, mildew, pollen, dust mites, animal dander, bacteria, and viruses.


•Gases resulting from human and pet metabolism (ammonia, certain alcohols, carbon dioxide, methane, etc.), gases that are by-products of combustion (carbon dioxide, carbon monoxide, sulfur dioxide, etc.), and gases that are released by synthetic and man-made products (formaldehyde, hexane, toluene, etc.)


•Metals such as lead (which used to be popular in paint), mercury (once used as a fungicide in paint and drywall compound), arsenic and chromium (widely used in chemically treated lumber).


•Minerals such as asbestos (found in some older insulation, vinyl tiles, and drywall compounds), mineral fibers and particles from fiberglass insulation, and air-borne minerals spewed out of humidifiers from tap water.


•Radiation from naturally occurring radon, electromagnetic radiation from wiring and electrical appliances, and radioactive waste in some smoke detectors and compact-fluorescent lamps.


Vapors, which in most houses means too much water vapor, something that can lead to pollutant problems such as mold growth—or rot.


6. What are VOCs and could they be big polluters in my home?


VOC stands for volatile organic compound. There are hundreds of different VOCs and they have two things in common—they contain carbon, and they evaporate quickly. Some are natural and relatively benign—baking bread and cutting onions releases VOCs. But other VOCs are synthetic and aren’t so safe to be around. They can be released by paints, solvents, caulking, and adhesives. Formaldehyde is probably the most recognized VOC. It’s widely used in plywood, particle board, finishes, and many other products. Some VOCs are irritants, carcinogens, and mutagens. They can be serious indoor polluters.


7. What is outgassing?


Outgassing refers to release of VOCs as a material ages or degrades. New-car smell is composed of various gases that are released from the synthetic materials making up a new automobile’s interior. As it turns out, many common building materials (cabinets, paneling, paints, etc.) outgas harmful VOCs.


8. I’m fairly certain my house is making me sick. Should I hire a company to test the indoor air?


If you feel better when you’re away from home, then get sick when you return, your house could indeed be making you sick. In some cases, professional air-quality testing can be helpful to understand why. But there are hundreds of possible pollutants, and testing for them all can cost hundreds, or thousands, of dollars. If you do such testing, you’ll probably be given a list of perhaps a hundred pollutants unique to your house. Because there are so many pollutants that haven’t been studied, you’ll know what you’ve got, but you won’t know what it means.


For the pollutants that have been studied, the guidelines as to what constitutes a safe exposure were often established for healthy workers in occupational settings. If you’re hypersensitive, you could easily be bothered by much lower levels—levels many experts consider safe.


A little detective work on your part will often provide more useful information than air-quality testing. For example, ask yourself when your symptoms started. If it was after some remodeling, you might suspect the building materials. If it was after a new furnace was installed, your problem could be related to a fuel leak, combustion by-products, leaky ducts, or the materials the ducts are made of. If your house was recently weatherized, it may have been tightened to the point it no longer has enough fresh air, or the indoor air could have been contaminated with insulation. If you’ve had a flood, you should suspect mold. If you just built a new house, there can be a number of possibilities—outgassing from new materials, lack of ventilation, heating/cooling system problems, etc.


9. I’ve heard of something called a bakeout. Won’t that increase the outgassing rate and get rid of the VOCs in my house?


A bakeout seems like the perfect solution. It involves heating a building up to about 95°F for three days or so, while simultaneously airing it out with window fans. This is a simple solution to a complex problem, and it doesn’t always help. In fact, some studies have shown that the levels of some pollutants can actually increase after a bakeout.


10. How long does it take for a typical house to air out on its own?


This is a difficult question to answer because there are so many variables. For example, different brands of similar products outgas at different rates, the rate changes at different temperatures and humidities, and natural (or mechanical) ventilation is a factor. Plus each different VOC has its own particular outgassing characteristics. As an example, formaldehyde (which is commonly used in kitchen cabinets and wall paneling) typically has a half-life of 3 to 5 years. So, these products will only lose half their formaldehyde in that time. And it’ll take another 3 to 5 years for half of the remaining formaldehyde to be released, and so on. Because outgassing decreases with time, older houses often have lower levels of VOCs than new houses—if they’ve been maintained with healthy cleaning products and there’s been no recent remodeling.


(Note: This article is part of the original HHI Archives, and was believed to be accurate at the time of writing. The views expressed in this article are those of the author, and do not necessarily represent those of The Healthy House Institute, LLC.)


HHI Error Correction Policy

HHI is committed to accuracy of content and correcting information that is incomplete or inaccurate. With our broad scope of coverage of healthful indoor environments, and desire to rapidly publish info to benefit the community, mistakes are inevitable. HHI has established an error correction policy to welcome corrections or enhancements to our information. Please help us improve the quality of our content by contacting with corrections or suggestions for improvement. Each contact will receive a respectful reply.

The Healthy House Institute (HHI), a for-profit educational LLC, provides the information on as a free service to the public. The intent is to disseminate accurate, verified and science-based information on creating healthy home environments.


While an effort is made to ensure the quality of the content and credibility of sources listed on this site, HHI provides no warranty - expressed or implied - and assumes no legal liability for the accuracy, completeness, or usefulness of any information, product or process disclosed on or in conjunction with the site. The views and opinions of the authors or originators expressed herein do not necessarily state or reflect those of HHI: its principals, executives, Board members, advisors or affiliates.

Healthy Home Basics - Why are Houses Unhealthy?:  Created on February 1st, 2008.  Last Modified on February 28th, 2011


We do not strictly control Google ad content. If you believe any Google ad is inappropriate, please email us directly here.



Information provided by The Healthy House Institute is designed to support, not to replace the relationship between patient/physician or other qualified healthcare provider.

Education Partners



Popular Topics: Air Cleaners & Air Purifiers | Allergies & Asthma | Energy Efficiency & Energy Savings | Healthy Homes | Green Building
Green Cleaning | Green Homes | Green Living | Green Remodeling | Indoor Air Quality | Water Filters | Water Quality

© 2006-2018 The Healthy House Institute, LLC.


About The Healthy House Institute | Contact HHI | HHI News & Media | Linking Resources | Advertising Info | Privacy Policy | Legal Disclaimer


HHI Info