Multifaceted Approach to Assess Indoor Environmental Quality

Posted on by Ray Wells, PhD
  • Of new-onset asthma cases in adults, 15–23% are work-related asthma [American Thoracic Society 2004]
  • The highest percentage of work-related asthma occurred among operators, fabricators, and laborers (32.9%) [Worker Health Chartbook 2004]
  • Between 35 and 60 million of the 89 million indoor environment workers have building-related symptoms of eye, nose, and throat irritations or headache and fatigue [Mendell 2002]
bottles of cleaners
The points above very briefly highlight some of the issues related to indoor environmental quality. It has been estimated that indoor environmental quality-related health issues cost businesses in the range of $20–70 billion annually due to lost productivity, decreased performance, and sick absences. Some of these health effects include respiratory issues that could fall under the classification of work-related asthma. Work-related asthma is a subset of occupational lung disease which can be further subdivided into occupational asthma, which can be caused by exposure to a sensitizer or irritant at work, and work-exacerbated asthma, which is when pre-existing asthma becomes worse due to exposures at work.

The indoor environment has changed. Materials emitting high formaldehyde levels are being eliminated from indoor environments. However, many questions remain regarding occupational asthma and work-exacerbated asthma and the indoor environment. What are the irritants/sensitizers that cause these diseases? Can they be controlled? What is the actual physiological mechanism? What are the actual exposures in the workplace? There is probably no single one chemical exposure responsible for these illnesses, but more likely a mixed exposure of chemical classes such as particulate matter and oxygenated organic species (oxidized volatile organic compounds that are likely biologically reactive and potentially cause cell damage and increase susceptibility to disease).

The possible answers to these questions might be found in investigating the chemistry of volatile organic compounds found in the indoor environment, developing new sampling methods, and improving assessments of chemical health effects. Consumer products used in indoor environments for cleaning, surface finishing and deodorizing are typically mixtures of many chemicals. Some of these are volatile organic compounds, meaning they evaporate into the air, and others are non-volatile, meaning they adhere to the surface. There are additional reactants in the indoor environment which can facilitate the oxidation of these consumer products. The recent emphasis on “natural” or “green” cleaning products has led to an increase in the use of terpenes (hydrocarbons produced by plants—particularly conifers) like alpha-pinene, limonene and delta-carene in cleaners and air fresheners. However, natural does not always mean safe. Terpenes can react with components in the indoor environment to form new chemicals that might be the irritants responsible for the observed increases in work-related asthma. Many of these oxidation products are not captured by conventional sampling methods, leading some researchers to suspect that workers who are exposed to oxidized chemicals may not know it.

To address this research question, the National Institute for Occupational Safety and Health (NIOSH) has developed expertise in investigating the fundamental chemistry of several chemicals in consumer products that may be used in an indoor environment. These investigative efforts have produced many important insights into a chemical’s fate in the indoor environment, possible new sampling techniques and identification of chemical structures that could lead to health effects.1,2,3,4,5,6

Indoor reactions are initiated mainly by ozone, a pollutant, which is transported from the outdoor environment into the indoor environment by building ventilation. NIOSH research has shown that when combined with ozone, one of the common components of pine oil cleaners, alpha-terpineol, transforms into many oxygenated organic compounds in both the gas-phase and on surface reactions creating new products potentially harmful to those exposed. Similar reactions were observed with many of the terpenes investigated.

Given that these new oxygenated species are not detected by conventional sampling methods, new techniques are needed to assess worker exposure and the potential health risk. These reaction products need to be stabilized to survive the conditions necessary for analysis. NIOSH is working to modify the current stabilization technique so that it can be used by industrial hygienists in the field.

Once we have a better understanding of the exposures created by these products we can work to better understand the health effects caused by indoor pollution. Recent research has shown that products created by these reactions could be sensitizers and irritants contributing to the health effects of those exposed. Additional research is needed to confirm these findings. As we move forward, the following questions continue to motivate this research:

  • What are the chemical structures that comprise “missing” or undetected carbon?
  • How are the reaction products partitioned in gas phase or particulate phase?
  • Does exposure to mixtures of different oxygenated organic compound structures result in disease “greater” than the sum of the parts, i.e., do the reaction products combine to result in a more “toxic” mixture?

Dr. Wells is Team Leader of the Gas and Vapor Team in the Exposure Assessment Branch in the NIOSH Health Effects Laboratory Division.


  1. Anderson, S. E.; Wells, J. R.; Fedorowicz, A.; Butterworth, L. F.; Meade, B. J.; Munson, A. E. Evaluation of the contact and respiratory sensitization potential of volatile organic compounds generated by simulated indoor air chemistry. Toxicological Sciences 2007, 97, 355-363.
  2. Wells, J. R. Gas-phase chemistry of alpha-terpineol with ozone and OH radical: Rate constants and products. Environmental Science & Technology 2005, 39, 6937-6943.
  3. Weschler, C. J.; Wells, J. R.; Poppendieck, D.; Hubbard, H.; Pearce, T. A. Workgroup report: Indoor chemistry and health. Environmental Health Perspectives 2006, 114, 442-446.
  4. Forester, C. D.; Ham, J. E.; Wells, J. R. Geraniol (2,6-dimethyl-2,6-octadien-8-ol) reactions with ozone and OH radical: Rate constants and gas-phase products. Atmospheric Environment 2007, 41, 1188-1199.
  5. Ham, J. E.; Wells, J. R. Surface chemistry reactions of alpha-terpineol [(R)-2-(4-methyl-3-cyclohexenyl)isopropanol] with ozone and air on a glass and a vinyl tile. Indoor Air 2008, 18, 394-407.
  6. Pacolay, B. D.; Ham, J. E.; Slaven, J. E.; Wells, J. R. Feasibility of detection and quantification of gas-phase carbonyls in indoor environments using PFBHA derivatization and solid-phase microextraction (SPME). Journal of Environmental Monitoring 2008, 10, 853-860.
Posted on by Ray Wells, PhD

68 comments on “Multifaceted Approach to Assess Indoor Environmental Quality”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    We have evidence of 5 separate meningiomas occurring in a primary care physician’s office over 3 yrs. Any idea besides potential radiation from x-ray unit as possible cause?

    Our research on volatile organic compounds in the indoor environment is not looking at cancer as an endpoint. The development of cancers is complex and currently I am not aware of any research linking the chemistry of the indoor environment to cancer.

    The toxic chemical soup that Americans are breathing at work is excerbated by the fragrance that is contained in almost every personal care product used by individuals. The respiratory and neurological effects of fragrance can be devastating financially and personally to the individual sensitized to these chemicals. The FDA “trade secret” rule provides a loophole for manufacturers using petroleum chemicals in products that allows the word “fragrance” to cover the ingredients used.

    I am sensitized to chemicals such as quaternary ammonium, roofing tar, fragrance, second-hand smoke, floor stripping products, air fresheners. My damaged health started with quaternary ammonium that resulted in occupational asthma in 1998, then further sensitization resulted RADS in 2000. I can no longer practice nursing due to the lung damage and am working towards a Ph.D. in nursing with a focus on occupational health. I advocate for organizations to reduce fragrance in the workplace and have developed policy templates for this purpose that I share nationally. Fragrance has a personal cost to the individual and certainly a loss of productivity cost to employers as well as contributing to the toxic chemical soup within buildings. I have many literature resources that I will share with anyone interested in this topic. Fragrance in the workplace is the new “second-hand smoke” resulting in adverse health effects for workers. All Americans have the right to work in a healthy environment that does not compromise their health. A position statement from NIOSH on the adverse health effects of fragrance would be greatly appreciated.

    I am a patient safety researcher and an MPH student at UM. From reading your article and the comments, I wonder if the materials released during and after construction of our workspace should not be included to the pollutant mentioned above. Furthermore, do you think it is possibile that there is an over-time cumulative effect of free radicals on airborn particles released from the construction materials? To my knowledge, there are studies that show the effect of constructions on nosocomial infections in hospitals. Thank you for your comments.

    The alternate analytical techniques we are developing could be used for sampling during construction. The long-term cumulative effect of radicals on particulate matter is an interesting research area that is challenged by the difficulty in accurately detecting free radicals on particles as well as gaps in the complex toxicology.

    Construction work can release significant particulate matter, usually consisting of building materials. During renovation of work spaces, mold could be released into the air from contaminated surfaces and inner building spaces.

    I found out that ionic air purifiers have been demonstrated to release potentially unhealthy levels of ozone. I was wondering if any other electrical or electronic appliances we use such as desktop computers also contribute to indoor ozone pollution. Thank you in advance for your valuable input.

    Office equipment emissions have been a research topic due to the increases in the use of computers and printers. There are several publications in the scientific literature on this topic (the first one is a review):

    ◦Title: Indoor pollutants emitted by office equipment: A review of reported data and information needs.
    Author(s): Destaillats, H; Maddalena, RL; Singer, BC, et al.
    Source: ATMOSPHERIC ENVIRONMENT Volume: 42 Issue: 7 Pages: 1371-1388 Published: 2008
    ◦Title: Characterization of VOCs, ozone, and PM10 emissions from office equipment in an environmental chamber.
    Author(s): Lee, SC; Lam, S; Fai, HK
    Source: BUILDING AND ENVIRONMENT Volume: 36 Issue: 7 Pages: 837-842 Published: 2001
    ◦Title: Emission of ozone and organic volatiles from a selection of laser printers and photocopiers.
    Author(s): Tuomi, T; Engstrom, B; Niemela, R, et al.
    Source: Appl Occup Environ Hyg Volume: 15 Issue: 8 Pages: 629-34 Published: 2000 Aug

    Thank you.

    Instead of “chasing the culprit” (i.e., chemicals), would a surveillance system be helpful to identify epidemiologic charachteristics for chemical air contamination? What is your opinion about using lipid peroxidation study of exhaled air (clearly, with appropriate washout period)?

    Over the last couple of years we have been working on connecting chemical structures to toxicology. The aim of this effort is to more easily describe indoor air quality based on concentrations of chemical classes (structures) rather than specific compounds. The surveillance system would still need the connection between exposure and health effect. The lipid peroxidation study would still benefit from knowing which chemical exposures led to the oxidation.

    I have been investigating the causes of building-related health effects as an independent consultant for over 18 years. It is my observation that, in most instances, health effects from low-level chemical exposures occur as a result of an acquired hypersensitivity being triggered. I think the focus of future research should be on the causal mechanisms of sensitization. Many workers become sensitized in environments where bacterial endotoxin is present such as in animal research laboratories and where metal working fluids are used. Occupants of water-damaged buildings become sensitized as a result of exposure to bioaerosol contaminants including LPS, B-glucans, fungal digestive enzymes, mycotoxins, etc. It is my opinion that people become sensitized when the innate immune system is potentiated and expression of the genes responsible for creating acquired or adaptive immunity occurs. The non-self chemicals in the blood at the time of innate immune potentiation are typically the volatile organic compounds absorbed in a contaminated indoor environment. An immune memory and sensory mechanism is created by the adaptive immune system to identify the foreign agent in the body in the future. The vanilloid receptor of the trigeminal nerve is often the receptor site where irritant chemicals are sensed (Pall 2004). Neurogenic inflammation results. This can cause virually all of the sick building syndrome symptoms reported (Meggs 1993).

    Pharmaceutical researchers have proposed the “danger hypothesis” to describe how cellular damage might potentiate the innate immune system to cause drug hypersensitivity reactions. This may explain how oxidative chemical species are associated with sensitization.

    Please make an effort to study the PEOPLE who become sensitized and not just do toxicology studies on the environmental chemicals. It’s all about how (and which) people become sensitized and the environmental exposures that determine what non-self substance in the body the adaptive immune system creates a defense against. This substance will become the future trigger of a neurogenic hypersensitivity inflammatory response.

    Thank you for your insight and comments. Risk assessment includes hazard identification, evaluating dose-response, exposure assessment and risk characterization. The research my group is doing is an attempt to better describe the exposure.

    I concur with the previous comment about focusing on the “People”. In my opinion, a surveillance system that will record the type of workspace/environment will provide the link between the human aspect the the toxicology/immunology aspects. Monitoring concetrations of chemicals is essential for establishing risk factors. However, the potential effect may be identified by linking persons and their medical complaints to the spaces they reside or work. In fact a surveillance system may serve as an intial phase for a prospective cohort study. Your opinion?

    Improved surveillance of indoor work environments would be of great benefit to focus the research direction as there are hundreds of chemicals present. Surveillance data would support or challenge our hypothesis of the importance of the oxidized volatile organic compound reaction products.

    In your article you mentioned that NIOSH research has shown that when combined with ozone, one of the common components of pine oil cleaners, alpha-terpineol, transforms into many oxygenated organic compounds in both the gas-phase and on surface reactions creating new products potentially harmful to those exposed. Does the reaction take place on recently applied the pine oil cleaners only? Are there any other free radicals generated in the process, which may continue the reaction?

    Our surface experiments were conducted over a 72 hour time period and we currently do not know the chemistry over longer periods of time. We have not investigated the complete pine oil cleaner formulation. The hydroxyl radical and the Criegee biradical are the most likely radicals produced during the reaction. However, these radicals are fairly reactive and are likely to react with surfaces or other volatile organic compounds present.

    Do the ozone free radicals interact with the pine oil cleaners immediately after the later have been applied? For how long does the reaction last, and does it produce other ‘nascent’ free radicals?

    The rate of ozone reaction is dependent on both the initial ozone concentration and the reaction rate constant. Our work has shown that the ozone/alpha-terpineol reaction is expected to be faster than typical building air exchange. The actual reaction itself (ozone + alpha-terpineol) occurs in a fraction of a second. There are other radicals that can be formed such as the hydroxyl radical and the Criegee biradical. However, these radicals are fairly reactive and are likely to react with surfaces or other volatile organic compounds present.

    I am a graduate student at University of Miami in an Environmental Health course. You mention consumer products in your article. Do you have a list of products that are safest for indoor air quality in the home?

    Also, is there any practical way for people to assess the air quality in their own homes?

    The National Institute for Occupational Safety and Health conducts research and prevention efforts to protect workers in occupational settings. While the results of our research can be applicable for the general public, this is not the focus of our research. You may want to check with the Environmental Protection Agency regarding products for use in the home. I’ve included a few links below.

    ◦EPA Indoor Air site
    ◦EPA Introduction to indoor air quality
    ◦EPA Formaldehyde from pressed wood
    ◦EPA Household cleaning products

    While NIOSH is not conducting research on this aspect of the building environment, it is reasonable to think that chemistry could occur in the air ducts. If oils and other organic substances are removed from the ducts the chance of oxidation chemistry should be reduced.

    I live in an apartment in Phoenix whose management is having some of the apartments remodeled. They are laying laminate on the countertops and using polyurethane or a type of lacquer. The fumes are coming into several of the surrounding apartments. We’re not sure if it is coming through the air conditioning, the vents, the walls, kitchen fan, who knows? The management has been told that this is making people sick, there are children in some of these apartments, and yet they are continuing on without ventilating the apartment they are working on. I personally made them open up the patio door of the offending apt. and put a fan in it. I was very sick for a night and a day. Is there a federal, state, county, or municipal department that you know of that would deal with this matter? I have called many departments in the City of Phoenix (fire, neighborhood services, development services), Maricopa County Environmental Services, and they all say they don’t deal with issues like this. Any help would be appreciated before we are all asphyxiated. Thank you.

    I work in a fast food restaurant and the vents over the fryers have not been working properly and I have experienced the worst asthma attacks lately especially when they went completely out and the store filled with smoke. What are the dangers of breathing the smoke for long periods of time besides my asthma getting worse. Three employees work at this business and has been reprimanded for taking time off due to our asthma.

    We need help. Thank you so much

    There are many exposures in kitchens that could trigger asthma attacks. Workers in the food service industry are exposed to multiple respiratory hazards including allergens and irritants. Asthma has been linked to exposure to aerosolized food agents such as egg proteins, crab, salmon proteins, enzymes, and organic dusts from tea, coffee, and spices. Baker’s asthma which results from sensitization to wheat, rye, or barley flour is one of the most common causes of occupational asthma worldwide. NOx, an irritant gas, is generated by use of gas cooking appliances. It has been linked to an increase in sensitivity to allergens in asthmatic people and exacerbation of asthma. Additionally, NOx is strongly correlated to the presence of other harmful pollutants, including carbon monoxide, polycyclic aromatic hydrocarbons (PAHs), and soot. Cooking with a wood fire can generate high levels of particulate matter that can be an irritant to the lungs.

    You were specifically concerned about fryers. Cooking oil fumes, such as those from Canola oil, lard, and peanut oil, have been shown to have a mutagenic effect on lung tissue. While the oils themselves may contain a small amount of toxic chemicals, heating these oils vaporizes the chemicals, including alkanals, alkenals, and aldehydes. The concentration of volatile emissions appears to be related to cooking temperature, with higher amounts being generated as temperatures increase. A large amount of oil fumes can be emitted during deep frying. The type of food being cooked can also affect the amount of volatile vapors released. Kitchens that cook foods high in fat, or those that produce more fried foods, have been shown to have higher levels of PAHs. Kitchens that have dirty cooking surfaces also have increase risk for exposure to PAHs, since these chemicals are can be concentrated in the scrapings off the grill.

    Faulty ventilation causing smoke exposures should be fixed. If the situation has been brought to your employer’s attention and has not been corrected, there are some groups that might be able to help. You may want to call the local health department to see if they have any regulatory/inspection authority regarding the ventilation (or lack of) & system performance. If the ventilation inlet may pose a fire hazard, the local fire department may be a resource. You may want to request a Health Hazard Evaluation from NIOSH. Information about the program and instructions for requesting a Health Hazard Evaluation are found on the internet at We may not always be able to conduct a site visit, but could interact with management and provide direct guidance on ventilation systems maintenance as well as asthma risk factors in the workplace & prevention. Finally, the Occupational Safety and Health Administration (OSHA) enforces safe and healthy work conditions. If the situation remains unresolved, you may wish to file a complaint with federal OSHA or state OSHA (if your state has an approved state OSH program). However, OSHA would only be able to issue a citation if it determined that there was a violation of the law.

    How can an individual request to have a building (their workspace) evaluated for indoor air quality? A number of people in my building are complaining of sore throats and increased allergy symptoms, with symptoms disappearing when they are away from the building.

    You can request a Health Hazard Evaluation from NIOSH. Information about the program and instructions for requesting a Health Hazard Evaluation are available on the Information about the program and instructions for requesting a Health Hazard Evaluation are available at We do not always find it necessary to do a field investigation. When this happens, we contact the person(s) who requested our assistance and provide information and guidance. When the request is from employees, we may also contact the employer. The Occupational Safety and Health Administration (OSHA) enforces safe and healthy work conditions. If the situation remains unresolved, you may wish to file a complaint with federal OSHA or state OSHA (if your state has an approved state OSH program). However, OSHA would only be able to issue a citation if it determined that there was a violation of the law. You can also find state and regional contact information for the Environmental Protection Agency.

    I work in a school and many workers have several symptoms over several years. Mainly sinus infections and resp. symptoms. In one of the buildings, you can see the mold on the ceiling in the old gym. They have many roof leaks in the main building and when ceiling tiles are down, you can see the mold on the duct work. You can smell it in the carpets, which on certain sides of the school,flood everytime it rains. Not only is staff sickened,but we have over 400 students exposed to this. Where do we complain?

    A good amount of mold will almost surely get take form anywhere is provided suitable conditions. Aside from chemicals we should make sure that the spaces are clean.

    For approximately 6 months I have been experincing all types of physical issues (typical SBS symptons) in my office. Paticular issues are senstivity to odors (especially newspapers and sweating under the eyes and on scalp.) Preliminary Air quality and other environmental testing have revealed nothing out of range. I do not have any symptons at home and the physical issues generally are gone afew hours after leaving work. I originally thought that a new copier in the area was the problem but test results show nothing as of yet. I was interested in Mr. Temes comments from 4/15/09.How can I get more information on his comments? Also, is there any data on copiers causing problems? Thank you

    I am not familiar with the references cited by Mr. Temes. A quick search revealed the following possible articles but I cannot be sure as he did not include complete citations. I have also included the reference to an article on office equipment (Destaillats). It is possible that a copier could produce ozone that could initiate adverse reactions.

    Pall ML, Anderson JH. The vanilloid receptor as a putative target of diverse chemicals in multiple chemical sensitivity. Arch Environ Health. 2004 Jul;59(7):363-75. Review.

    Meggs WJ. Neurogenic inflammation and sensitivity to environmental chemicals. Environ Health Perspect. 1993 Aug;101(3):234-8. Review.PMID: 8404760

    Destaillats, H et al.Indoor pollutants emitted by office equipment: A review of reported data and information needs ATMOSPHERIC ENVIRONMENT, 42 (7): 1371-1388 MAR 2008

    Dr. Wells, while searching online for technical papers that address the value of duct cleaning as a means of improving IAQ I came accross your blog.

    I am the principal owner of an ozone service company located in Columbus, Oh. Our services are geared 100% toward the improvement of IAQ. Even after several years in this business I remained amazed at the good things that ozone can do to a residential or comercial indoor environment. I should make it clear that I and my company, do not support the use of ozone in home and work environments while occupied. We perform our service when people and pets are not in the space and do not allow them to return until our meter shows ozone ppm levels to be well below the EPA’s recommended TLV of 0.07 ppm.

    Yes, we are aware that there are chemical reactions taking place during the antibacterial air treatments that we perform. I am concerned that there is so little research available that studies these reactions and makes an effort to quantify the production of chemicals that spring from these treatments. There are few published TLV’s for these undesirable chemicals that we can observe and plan for. We are very safety minded and research ozone studies regularly in hopes of finding something concrete that we can use as a benefit or create a safety process to control if undesirable.

    In addition to performing our service only when people and pets are not in the space, we also use an air scrubber as a final step in our air cleansing process that employs a 3 phase filtration process to remove, gasses, chemicals, and particles. When we finish, the air is very clean. We’ve actually had customers break into tears because they could breathe freely without their sensitivities being attacked by their own home.

    Dr. Wells, sorry for this long winded comment but ozone gets a lot of bad press. I will be the first to agree that ozone can have undesirable effects but I will qualify that by saying only if it is “uncontrolled.” We control our use of mother nature’s most powerful antibacterial agent and shape it to perform good things for our IAQ.

    Bob Marvin
    Clean Air Resources of Ohio

    I am currently working on IAQ investigation in which the ultrafine particle counts (8,000 to 24,000 pt/cc) seems to be higher than expected for the environment. The complaint (multiple asthma/respiratory) area is an office environment in health care/clinical setting. The area is served by central HVAC (VAV, Hot Water Reheat, Direct Steam Humidification, Ducted Returns), and with 2-stage filtration (MERV 8 and 12-14). Other Parameters: Carbon Dioxide 500-600ppm, Temperature 71-76°F, RH 30-40%, positive pressure relationship to hallways and adjacent areas, no clear source(s) identified in immediate work environment, and so far HVAC engineers have not reported anything unusual with system.

    Based on my experience and comparison with other similar environments particle counts are typically around1000 to 5000 pt/cc. On few occasions over the last few years have seen other areas with relatively short lived spikes in the 8,000-19,000 pt/cc range associated with vehicle exhaust migration or copier/printers. But in this particular office the counts (data logging) have been consistently elevated (12,000 to 16,500 pt/cc) for multiple hours over several days at a time. After conducting particle counts for almost two weeks, I did record a drop off in counts (1000 to 4000 pt/cc) for 1-2 days when weather condition changed (Slightly warmer ~ 50°F and Rain). However, counts increased back to 12,000 to 24,000 pt/cc) as soon as outside temperature and humidity/dew point dropped in the last 2 days. I have also noted spikes of 2000-5000 pt/cc over the room counts or backgrounds when readings taken inside supply duct just before diffusers.

    I realize this is lot of details, but with no outside or internal source clearly noted so far, I am looking for feedback and thoughts on these counts. One specific question: Anyone seen this similar pattern or counts associated with humidification systems particularly direct steam? If so, anyone conducted further analysis (i.e. water vapor, contaminants, steam additive,etc.) Given my review of the literature (case reports, increasing research on potential health effects from ultrafines) it would seem to me that we should follow-up and try determine source and make attempt to control or eliminate. I would like add at this point the engineers are reluctant accept this may be problem and take any additional steps (i.e. turn off humidifier or conduct systematic evaluation) Thanks for your thoughts and consideration on this post.

    Ron Howell, Industrial Hygienist

    I consulted with a NIOSH colleague who suggested that it is unusual to steam humidify an office space, even in a health care facility. He suggested evaluating the steam humidification system further to see if it is the particulate source. This could be achieved by turning the machine off and monitoring to see if the counts fall back into a “normal” range.

    Particle formation mechanisms in indoor environments are complex and an active research topic. There are several ways to think about particles: size, number, and composition as well as formation rate. For the indoor environment there could be chemical emissions that react with ozone present to form oxygenated organic compounds which can interact with water to form particulate matter. I have not conducted particulate sampling in office spaces so I cannot interpret the data you present. I do think you have captured some important patterns as well as correlated the environment with worker health effects. There could be particular cleaning products that may slowly react on surfaces such as carpet to be a source for the long term elevated particle counts you are observing. How willing is building maintenance to try another product to simply see if particle numbers decrease? I have included one reference describing particulate matter formation in simulated indoor conditions.

    Coleman, BK; Lunden, MM; Destaillats, H; Nazaroff, WW. Secondary organic aerosol from ozone-initiated reactions with terpene-rich household products ATMOSPHERIC ENVIRONMENT, 42 (35): 8234-8245 NOV 2008

    In your entry above you noted “The recent emphasis on “natural” or “green” cleaning products has led to an increase in the use of terpenes (hydrocarbons produced by plants – particularly conifers) like alpha-pinene, limonene and delta-carene in cleaners and air fresheners.

    However, natural does not always mean safe.” Can you be more specific about the dangers, if any, of terpene-based cleaning products? Please include data that indicates the presence of plant-based hydrocarbons.

    These terpene compounds can react with ozone present in indoor environments leading to the formation of oxygenated organic compounds in both the gas phase and particulate phase. Exposures to these transformation reaction products may lead to health effects such as respiratory problems. There have been several publications presenting data characterizing both product formulations and emissions after product use. I have included references below.

    Author(s): Singer, BC; Coleman, BK; Destaillats, H; Hodgson, AT; Lunden, MM; Weschler, CJ; Nazaroff, WW.
    Title: Indoor secondary pollutants from cleaning product and air freshener use in the presence of ozone Source: ATMOSPHERIC ENVIRONMENT, 40 (35): 6696-6710 NOV 2006

    Author(s): Zuskin, E; Schachter, E ; Mustajbegovic, J ; Pucarin-Cvetkovic, J ; Doko-Jelinic, J ; Mucic-Pucic, B
    Title: Indoor air pollution and effects on human health
    Source: PERIODICUM BIOLOGORUM, 111 (1): 37-40 MAR 2009

    Author(s): Fisk, WJ (Fisk, W. J.); Mirer, AG (Mirer, A. G.); Mendell, MJ (Mendell, M. J.)
    Title: Quantitative relationship of sick building syndrome symptoms with ventilation rates
    Source: INDOOR AIR, 19 (2): 159-165 APR 2009

    Author(s): Kim, H (Kim, Haejin); Bernstein, J (Bernstein, Jonathan A.)
    Title: Air pollution and allergic disease
    Source: CURRENT ALLERGY AND ASTHMA REPORTS, 9 (2): 128-133 MAR 2009

    Post 21 (3-2-10)
    In follow to my previous post (21) and response we have been able to determine that the humifier appears to be associated with UFP counts we had been seeing in the office space. We conducted multi point counts (AHU post filters (MERV 14) supply duct off AHU in ME room post humdifer and supply in room duct/room) We conducted test with humider off, 20%open, and then 70% open. We noted spikes around 50,0000 pt/cc post humidifer ME room supply duct and Office area with the humidifer at 70%. The UFP counts were 400-600 with the humidifer off and 20% open. We are planning on conducting a more detialed visual examnation of the internal surface (humidifer and ductwork). We are also meeting with representatives of [the company] to discuss this issue. Trying to determine if this unusal or a problem with humidifer. I would be interested in hear others who may have insigth or knowledge on direct injection steam humidifcation.

    Dear Dr. Wells,
    I have heard through the grapevine that the CDC has initiated a fragrance-free policy for their workspaces. Is this true? I would like to receive a copy of this information. If the CDC is recommending a fragrance-free environment for the health of their employees, shouldn’t you be recommending it for all workspaces?

    The EPA IAQ Tools for Schools Kit includes valuable information and suggestions for indoor air quality improvements in schools. Wouldn’t a recommended fragrance-free protocol assist with limiting asthma triggers and be included in this kit as well?

    A mere suggestion by the CDC or EPA would certainly go a long way by assisting employers with setting up a protocol and policy. Employers are lost when it comes to how to institute a scent-free program and therefore find requests to minimize fragrances cumbersome.

    I look forward to receiving your fragrance-free policy (I think June 09?) and your thoughts on this subject soon.

    Thank you for your time.


    In June 2009, CDC issued the Indoor Environmental Quality Policy, which does prohibit the use of scented or fragranced products in all interior spaces. This is an internal CDC document. Requests for specific documents that are not available via the CDC and/or NIOSH websites should be submitted through the CDC/ATSDR Freedom of Information Act (FOIA) Office at the following address:

    Attn: FOIA Office, MS-D54
    1600 Clifton Road, N.E.
    Atlanta, GA 30333

    Fax number: 404-498-1575
    Phone number: 404-498-1580*

    NIOSH’s guidance for good IEQ practice recognizes fragrances as sources of IEQ problems. The guidance includes a recommendation that—as part of a strategic program for proper workplace IEQ—air fresheners and room deodorizers not be used in the workplace.

    Does workplace photocopy toner exacerbate asthma and, if so, can reduction to exposure help or is any exposure a trigger and, therefore, exposure should be absolutely avoided?

    Possible health effects from toner would depend on what the toner is made of. The following article may be of use.

    Destaillats, H et al.Indoor pollutants emitted by office equipment: A review of reported data and information needs ATMOSPHERIC ENVIRONMENT, 42 (7): 1371-1388 MAR 2008

    Some very good information here. I guess most folks know now that the Environmental Working Group website has listed findings of pollutants in popular home and school cleaning supplies. Comet cleanser, when used, emits something like 146 polluting particules, several of time carcinogenic. EWG has useful information for daily living.

    Has anyone conducted an assessment of potential ozone exposure from a product called LaundrOzone? (see link below) These devices come with ozone monitor; however I am curious if anyone has conducted independent assessment or testing. Even if ozone concentrations are below OEL there are multiple research articles indicating potential reaction byproducts and secondary pollutants at levels below these limits. I know ozone is proven technology for water purification and disinfection. However, any insight on efficacy of this technology in laundering operations would also be welcomed.


    Ray and Ken Wallingford, Deputy Chief of the NIOSH Hazard Evaluations and Technical Assistance Branch says:

    We are not aware of independent testing of this product. Some states (such as California) have regulated ozone generators and require the manufacturers to test them for ozone emissions but we do not know if that requirement applies to water injection systems. If it does, there may be some test data available from those states that would be applicable.

    Determining what is a “safe” ozone exposure level has been a major challenge for regulators of outdoor pollution. The EPA has prepared a three part report entitled “Air Quality for Ozone and Related Photochemical Oxidants” which reviews the pertinent literature and research up to ~2005. It is located at this web site: There continues to be significant research activity towards determining a concentration of ozone that does not cause some sort of physiological change. A recent paper determined that health effects for elderly emergency room patients with COPD could be associated with a 13 ppb increase in ozone concentration (Halonen, et al. “Ozone and cause-specific cardiorespiratory morbidity and mortality”(2010) JOURNAL OF EPIDEMIOLOGY AND COMMUNITY HEALTH 64(9) pp. 814-820.) You also correctly point out that ozone has the added capacity to initiate the formation of both particulate matter and oxidized organic compounds on both surfaces and in the gas phase. Caution should be advised for devices that purposefully increase ozone concentration indoors.

    Thanks for this helpful blog.

    Our village’s kindergarten burnt 10 months ago, the fire was in one room, the kitchen (fridge and oven etc were damaged) but the whole space filled with much soot. Renovation was done by a non-professional company, which apparently did not remove all the contamination before repainting and cleaning up. A test for chemicals was done in the air but it was very partial and the tests were limited. We were wondering what sort of tests should be done, as there is still a trace of smell when coming into the building, which seems to depend on time of day and temperature. What types of tests would you recommend? I know there are hundreds of materials to search for, which are the most important to test in s space used 40 hours a week by 3-6 year old kids? We have funding to pay a private company to run the tests but it seems they offered mostly formaldehyde, COs, CO and few other partial tests which do not seem to be those needed here.

    Also, how long should the tests run? They proposed 2-3 hours, it seems too short to get a good representation. Should the tests be repeated several times (hours/days/weeks)?

    Thanks in advance,
    S Kark

    The Environmental Protection Agency (EPA) would be able to best provide information about your concerns for 3-6 year old children in a school setting. They have an IAQ Tools for Schools Program. In the left hand navigation bar of this site there is information on Resources for Schools and Frequent Questions.

    Residual smoke odor can be removed with a rented ozone generator used during the weekend when occupants are not present. Fires are put out with water, so water damage may be an issue, with bioaerosols causing odors. We don’t think there is any sampling that would be useful.

    Has NIOSH conducted exposure assessment during/after floor stripping and finishing? The products in question contain (strippers:ethanolamines, phenoxyethanol, alkoxylated alcohol, diehtylene gylcol monophenyl ether)

    (Finisher: ethanol 2-(2-ethoxyethoxy 111-90-0) We have conduct some initial monitoring with photo ionzation detector and noted 200-300 ppb during stripping and 2000-6000 ppb during waxing/finish application. The odor complaints and symptom reports seems to be mainly associated with finishes process (multiple layers of wax/finisher are applied) Any insight or monitoring data would be most welcomed.

    NIOSH has not done systematic research on floor stripping and floor stripping chemicals but we did conduct a Health Hazard Evaluation at the University of Michigan hospitals to evaluate floor care workers’ exposures to glycol ethers during wax stripping and waxing activities.

    I have suffered a severe condition diagnosed as bronchial hyperreactivity and multiple chemical sensitivity. It has been caused by the pungent vapours released by a PHOTOCOPIER first and years later by a LASER PRINTER which were much used in an unventilated place. There was first much confusion about the illness, initially considered to be viral, allergic or psychosomatic until clear evidences of the toxic inhalation showed up.

    I have found reports of other persons suffering different health problems all over the world due to these office machines. Would anyone in this forum know of precise persons made ill by these machines and what happened to them? I am sure that there must be more, particularly coming from the 80’s and 90’s when copy machines were intensively used before the era of the internet and intranets.

    I would like to hear more about this issue and I would appreciate any publicity to my story that your readers could provide, so that other persons made ill like me can realize what is the matter and take precautions to avoid unnecessary risks. Please note that I live in Europe and US medical-legal complaint regulations will not apply to my case.
    Thanks for any comments.

    Please see the responses to comments 4 and 19 for references to articles addressing copier and office equipment emissions. Please note that NIOSH does not post e-mail addresses or phone numbers on the blog and does not post personal identifying or private medical information about a third party, especially information restricted from release under the Privacy Act or the Health Insurance Portability and Accountability Act (HIPAA). For more information see our Comment Policy

    Have a question: we do sell and advertize indoor grills, is it any danger to inside grillinG?
    Thanks, Nor

    Any grill that is based on combustion of coal, charcoal, natural gas, propane or other fossil fuel (i.e., not electric) will burn the fuel, reduce available oxygen and emit carbon dioxide, water, and may emit carbon monoxide, oxides of nitrogen, and partially burnt hydrocarbons among other potentially toxic chemicals. Without proper ventilation this could present a hazard. I suggest you refer to the manufacturers’ instructions and warnings for information about the particular models in question.

    I work in an clinical office where the photocopier extracts its copies about 3-4 feet to my back. Copies are being made of flood damaged papers that have a nauseating odor. And the warmer the copier gets the stronger the smell. The papers had been in a lower level office that was flooded with 4 feet of water during the last hurricane we had. 4 feet of water for 3 days, dried out and are being copied in the office where I sit. My thinking is that if these papers cannot be destroyed they should be sent out where this type of copying is done as routine. The smell is nauseating. Interested in your opinion! Am I wrong for complaining?

    After consulting with a colleague, we would advise that due to the moldy odor you report, the water -damaged documents should be copied off site, then discarded appropriately.

    Dear Sir / Madam:
    I am looking for class room training on Indoor Air Quality by NIOSH at reasonable price. I am federal civilan employee. Could you please provide me information ASAP to register for this training? I understand training is free to federal employees. Thank you.

    Some time ago, I read a paper about indoor water quality. However I have yet to capture a clear intention of the text. Therefore I want to ask about it. I wonder what are the factors that affect the indoor water quality ?


    @Bob – There absolutely IS an issue when it comes to air quality. I’m amazed that you would say or think differently!


    The climate change. Materials with a high concentration of formaldehyde in indoor EMIT. However, many questions about asthma and occupational asthma worsen the environment and the fragrance internal work.

    Indoor Air Quality is an incredibly important topic to educate the public on. More and more often, I see both homeowners and commercial building owners downplay the potential consequences in order to save time or money.

    The complete exit from the indoor working environment is not possible because 60 to 70 percent work force working towards improve productivity. But in the case of situation like this one can take timely break from work for 5 to 10 minutes and stretch himself in a outer environment like computer professional does while working on computer screen 2 minutes break can save your from eye disorders. Also for complete body fit it is required to drink plenty of water and that too from highest trusted water resource or water purifier that supply complete minerals to survive against all body attacks.

    Great information related multifaceted approach to assess indoor environmental quality. Thanks for share your unique information!

    I am so glad for this blog. I have suffered since 2007 with fragrances and chemicals in 2 work places. Left one employer due to my illness voluntarily. Not about to do it again but considering it. Struggles with employers and absences due to exposure at my expense, using my personal sick time and vaction allowances to recover from exposures to me is unexceptable. Being coached for absences will not be accesptable. Although they try to accommodate, but have not reviewed my accommodations to see if they are working, there is still not a “fragrance free Policy ” as my doctor suggested in writing. We still have those wearing extreme amounts of fragrances. And those are both men and woman, although management does attend to some issues, a fragrance free policy was suggested and they say they can not. Another sight with same company does have a policy. I am baffled how to approach the company about this issue.

    Indoor Environmental Quality is most simply described as the conditions . It includes air quality. But also access to daylight, pleasant, comfort should be sustainable materials that improve indoor environmental quality. Designing internal spaces with outside is amazing. Using natural light is also effective. Can u provide a good return on investment. Thanks for sharing.

    If the indoor environment can be controlled then it can definitely bring the positive output as per my personal experience can say.

Post a Comment

Your email address will not be published. Required fields are marked *

All comments posted become a part of the public domain, and users are responsible for their comments. This is a moderated site and your comments will be reviewed before they are posted. Read more about our comment policy »

Page last reviewed: January 30, 2020
Page last updated: January 30, 2020