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Draft Briefing Paper 07-1-95

IMPLICATIONS FOR HUMAN HEALTH

Indoor Air Quality

Summary of the Problem

The human health effects of indoor air pollutants are becoming increasingly evident as we recognize various physical, chemical and biological agents in the indoor environment. Building-related illnesses, sick building syndrome and, in the view of some, multiple chemical sensitivities have attracted attention by the public.

Canadian Recommendations1,2,3

  • Implement and enforce the current accepted guidelines for ventilation of buildings and indoor air quality (such as aldehydes, carbon dioxide, carbon monoxide, formaldehyde, nitrogen dioxide, ozone, particulate matter, sulphur dioxide, water vapour, and radon) in workplaces, schools, hospitals, and residential indoor environments.
  • Implement appropriate strategies to eliminate or reduce indoor exposure to biological agents and consumer products (such as chlorinated hydrocarbons, pest control products, product aerosols, fibrous materials, lead, polycyclic aromatic hydrocarbons, and tobacco smoke).
  • Continue and strengthen control of exposure to enviromental tobacco smoke.

Indoor Air Quality (IAQ)

"Good" indoor air quality refers to thermal comfort (from 20° C to 26° C with 45% to 50% of relative humidity), odor comfort and the acceptable levels of biological, physical and chemical agents in indoor air without undue risk to health of the occupants. Inadequate control of these indoor environmental factors may pose health problems. The "built environment" is unlike the natural, outdoor environment in that it is artificial and under human control. However, in practice, control of the indoor environment is not easy. Ventilation, for example, is a trade-off between climate control, air quality, and energy efficiency and it can be very costly to heat or cool incoming "make up" air in a large building.

Indoor air quality is not a new health concern. Air within homes in the past, and today in much of the developing world, was polluted by combustion products of unvented cooking and heating fuels by charcoal, wood, dung, kerosene or oil.4 Since World War II, people have spent most of their lives indoors (an estimated 70% of their lifespan in homes and offices). Health complaints are increasing since people work in sealed buildings which are, for energy conservation, reliant on complex ventilation systems with the decreased provision of fresh air and which use synthetic building materials. Increases in the cost of energy in recent years has made energy conservation in buildings a higher priority for builders and owners but problem associated with indoor air quality have become more widespread. Thus, awareness of the importance of indoor air quality is now growing.

Factors influencing the indoor air environment include the interaction of the physical layout (e.g., age, design, construction and maintenance) of the buildings, outdoor climate, outdoor air quality, the building's heating/ventilation/air conditioning (HVAC) system , potential sources of contaminants, and the building's occupants.2,5 Common contaminants found in the indoor environment include biologic agents or bioaerosols (e.g., microorganisms, pets or insects, pollens, spores, cells, and cell debris), combustion-generated products (e.g., carbon dioxide, carbon monoxide, nitrogen dioxide, ozone, and sulphur dioxide), respirable particulate matter and fibrous materials (e.g., asbestos and man-made mineral fibres), consumer products (e.g., furnishings and building materials like formaldehyde and volatile organic compounds (VOCs), pest control products, and product aerosols like hydrocarbons), environmental tobacco smoke, and radon.1,2,6-21

Individuals in the indoor environment are usually exposed to complex mixtures rather than a single pollutant. Assessment of indoor exposure for humans is therefore usually a complex task. Approaches to measuring individual indoor air pollutants can be categorized as (1) direct measurement which involves personal monitoring, biological markers or controlled human exposure studies (clinical studies); and (2) indirect measurement which are based on the microenvironmental model.22-25

Carbon dioxide has been considered as a general indicator of indoor air quality. The concentration of carbon dioxide in indoor air represents a balance between release metabolic activities of the human (or animal) occupants and combustion sources in the building and dilution and removal by the ventilation system of the building.1 A level of ventilation that maintains a low level of carbon dioxide within a building usually keeps concentration of other undesirable indoor contaminants acceptably low.

Human Health Effects

Sources of indoor air environment are diverse. The potential adverse health effects are diverse as well. Health concerns range from short-term annoyance, vague discomfort or irritation to chronic diseases (such as respiratory diseases, cancer and even death). The most common effect is a set of building-related illnesses and complaints, which are collectively called "sick building syndrome."

Sick Building Syndrome (SBS). Currently, there is no generally accepted clinical definition of SBS. In the literature, SBS generally refers to broad categories of symptoms and health complaints as clinical entities which are related to indoor environmental factors. These symptoms and complaints include irritation of eyes, nose, upper airways, throat and skin, odors, neurotoxic effects (nausea, dizziness, headache, loss of coordination, fatigue and irritability), respiratory disorders (asthma-like symptoms such as wheezing, cough, chest tightness and shortness of breath), skin dryness and irritation, and many less specific complaints.6,26-37 These symptoms are usually made worse by psychosocial factors such as emotional concerns, work stress, personal control and financial risk.31-32,38 Some cases of SBS are thought to be primarily the result of psychological factors, including the response to odors.

The National Institute for Occupational Safety found that 50% of SBS cases were associated with inadequate provision of fresh air without identifiable contaminants, 39% of cases were related to identifiable indoor or outdoor contaminants, and in 11% the causes were not clear.39 The mechanism of SBS caused by indoor environmental factors are still elusive. Biologic variability, e.g. host sensitivity or susceptibility, may explain the difference in responsiveness among occupants of a buildling to low levels of indoor pollutants.32,40-47

Building-Related Illnesses (BRIs). A BRI is a defined disorder that is related to indoor environmental factors, with appropriate clinical and laboratory findings. BRIs are less common than SBS. BRIs include asthma, hypersensitivity pneumonitis, humidifier fever, allergic rhinitis, and possible some infectious diseases like legionellosis, Q fever, and viral respiratory infections.34-35,37-38 BRIs differ from SBS in that they are well-defined clinical entities with known causes and may be encountered in settings other than buildings with indoor air quality problems.

Most indoor environmental factors that cause BRIs have been identified. For instance, irritants and allergens contribute to development of clinical asthma.38,8-52 The antigens associated with biologic agents (e.g. bacteria, fungi, insects) and possible chemicals have been causally related to hypersensitivity pneumonitis and humidifier fever.38 Respiratory infections have linked to inadequate ventilation, environmental tobacco smoke, combustion products and biologic agents.53-59 The mechanism of BRI caused by indoor environmental factors may involve immunologic reactions, infectious process, toxicity and irritation.38 In most cases, a BRI can be linked directly to a particular exposure, condition, or problem with the building, although it is sometimes difficult to identify a particular antigen in cases of asthma and allergic rhinitis.

Lung Cancer. Radon is ubiquitous in the indoor environment. Although lung cancer has been causally related to radon exposure in underground miners, whether there is an increased risk of lung cancer for the general population from exposure to low-dose indoor radon is currently inconclusive.60-63 A WHO Working Group recommended that when individual risks due to exposure to indoor radon exceed 10-3 per year, exposure should be considered severe.64

Environmental Tobacco Smoke (ETS). Currently, the evidence concerning ETS associated with the increased risk of lung cancer continues to grow. Epidemiological studies have shown a weak association between ETS and lung cancer but not a clear causal relationship.65-66 However, the level of carcinogenic activity in ETS now exceeds permissible exposure levels for some occupational carcinogens. As a result, ETS is increasingly controlled as an occupational health exposure in the workplace and as a public health issue in public places.

References

  1. Health Canada. Exposure Guidelines for Residential Indoor Air Quality. A Report of the Federal-Provincial Advisory Committee on Environmental and Occupational Health. Ottawa, Ontario, Environmental Health Directorate, Health Protection Branch, Health Canada, EHD-TR-156, 1990.
  2. Health Canada. Office Air: A Worker's Guide to Air Quality in Offices, Schools, and Hospitals. A Report of the Federal-Provincial Advisory Committee on Environmental and Occupational Health. Ottawa, Ontario, Environmental Health Directorate, Health Protection Branch, Health Canada, 93-EHD-174, 1994.
  3. Health Canada. Indoor Air Quality in Office Buildings: A Technical Guide. A Report of the Federal-Provincial Advisory Committee on Environmental and Occupational Health. Ottawa, Ontario, Environmental Health Directorate, Health Protection Branch, Health Canada, 93-EHD-166, 1993.
  4. Spengler JD, Sexton K. Indoor Air Pollution: a Public Health Perspective. Science 1983; 221:9-17.
  5. Spaul WA. Building-related factors to consider indoor air quality evaluations. J Allergy Clin Immunol 1994; 94:385-389.
  6. Brooks BO, Utter GM, DeBroy JA, Schimke RD. Indoor Air Pollution: an Edifice Complex. Clin Toxicol 1991; 29:315-374.
  7. Koutrakis P, Brauer M, Briggs SL, Leaderer BP. Indoor Exposure to Fine Aerosols and Acid Gases. Environ Health Persp 1991; 95:23-28.
  8. Hodgson MJ, Frohliger J, Permar E, Tidwell C, Traven ND, Olenchock SA, Karpf M. Symptoms and Microenvironmental Measures in Nonproblem Buildings. J Occup Med 1991; 33:527-533.
  9. Lofroth G. Airborne Mutagens and Carcinogens from Cooking and other Food Preparation Processes. Toxicol Lett 1994; 72:83-86.
  10. Kissel JC. Potential Impact of Deliberately Introduced Ozone on Indoor Air Quality. J Exposure Anal Environ Epidemiol 1993; 3:155-164.
  11. Gaensler EA. Asbestos Exposure in Buildings. Clin Chest Med 1992; 13:231-242.
  12. Tichenor BA, Sparks LA, White JB, Jackson MD. Evaluating Sources of Indoor Air Pollution. J Air Waste Manag Assoc 1990; 40:487-492.
  13. Gold DR. Indoor Air Pollution. Occup Lung Dis 1992; 13:215-228.
  14. Godish T. Indoor Air Pollution Control. Chelsea, Michigan: Lewis Publishers, 1989.
  15. Samet JM, Speizer FE. Introduction and Recommendations: Working Group on Indoor Air and Other Complex Mixtures. Environ Health Persp 1993; 101 (suppl 4):143-147.
  16. Samet JM, Speizer FE. Assessment of Health Effects in Epidemiologic Studies of Air Pollution. Environ Health Persp 1993; 101 (suppl 4):149-154.
  17. Alberts WM. Indoor air pollution: NO, NO2, CO, and CO2. J Allergy Clin Immunol 1994; 94:289-294.
  18. Hodgson M, Barch HL, Wolkoff P. Volatile organic compounds and indoor air. J Allergy Clin Immunol 1994; 94:296-303.
  19. Salvaggio JE. Inhaled particles and respiratory disease. J Allergy Clin Immunol 1994; 94:304-309.
  20. Lockey JE, Ross CS. Radon and man-made vitreous fibers. J Allergy Clin Immunol 1994; 94:310-316.
  21. Seltzer JM. Biological contaminants. J Allergy Clin Immunol 1994; 94:318-326.
  22. McDonnell WF. Utility of controlled human exposure studies for assessing the health effects of complex mixtures and indoor air pollutants. Environ Health Persp 1993: 101 (suppl):199-203.
  23. Wilcosky TC. Biological markers of intermediate outcomes in studies of indoor air and other complex mixture. Environ Health Persp 1993: 101 (suppl):193-197.
  24. Leaderer BP, Lioy PJ, Spengler JD. Assessing exposure to inhaled complex mixtures. Environ Health Persp 1993: 101 (suppl):167-177.
  25. Utell MJ. Assessment of acute effects in controlled human studies. Lessons from field studies. Ann New York Acad Sci 1992; 641:37-45.
  26. Apter A, Bracker A, Hodgson M, Sidman J, Leung WY. Epidemiology of the sick building syndrome. J Allergy Clin Immunol 1994; 94:277-288.
  27. Kreiss K. The epidemiology of building-related complaints and illness. Occup Med State Art Rev 1989; 4:575-592.
  28. Samet JM, Marbury MC, Spengler JD. Health effects and sources of indoor air pollution. Parts I and II. Am Rev Respir Dis 1987; 136:1486-1604.
  29. Molhave L. The sick buildings - a subpopulation among the problem buildings. In: Seifert B, Esdorn H, Fischer M et al. (eds). Indoor air 87: proceedings of the IV International Conference on Indoor Air Quality and Climate. Vol 2. Berlin: Institute for Water, soil, and air Hygiene, 1987:469-473.
  30. Tucker WG. Characterizing emissions and health effects of sources of indoor air contaminants. Ann New York Acad Sci 1992; 641:1-6.
  31. Hodgson M, Storey E. Patients and the sick building syndrome. J Allergy Clin Immunol 1994; 94:235-343.
  32. Skov P. The sick building syndrome. Ann New York Acad Sci 1992; 641:1720.
  33. Chang CC, Ruhl RA, Halpern GM, Gershwin ME. The sick building syndrome. I. Definition and epidemiological considerations. J Asthma 1993; 30:285-295.
  34. Sherin KM. Building-related illnesses and sick building syndrome. J Floride Med Assoc 1993; 80:472-474.
  35. Welch LS. Severity of health effects associated with building-related illness. Environ Health Persp 1991; 95:67-69.
  36. McDonald JC, Armstrong B, Benard J, Cherry NM, Farant JP. Sick building syndrome in a Canadian office complex. Arch Environ Health 1993; 48:298-304.
  37. Seltzer JM. Building-related illness. J Allergy Clin Immunol 1994; 94:351-362.
  38. Salvaggio JE. Psychological aspects of "environmental illness," "multiple chemical sensitivity," and building-related illness. J Allergy Clin Immunol 1994; 94:366-370.
  39. Samet JM, Spengler JD. Health effects and sources of indoor air pollution. Part II. Am Rev Respir Dis 1988; 137:221-242.
  40. Brooks SM. Host susceptibility to indoor air pollution. Allergy Clin Immunol 1994; 94:344-351.
  41. Bascom R. Differential responsiveness to irritant mixtures. Possible mechanism. Ann New York Acad Sci 1992; 641:225-247.
  42. Cometto-Muniz JE, Cain WS. Sensory irritation. Relation to indoor air pollution. Ann New York Acad Sci 1992; 641:137-151.
  43. Kjaergaard S. Assessment of eye irritation in humans. Ann New York Acad Sci 1992; 641:187-198.
  44. Berglund B, Lindvall T, Nordin S. Environmentally induced changes in sensory sensitivities. Ann New York Acad Sci 1992; 641:304-321.
  45. Meggs WJ. Neurogenic inflammation and sensitivity to environmental chemicals. Environ Health Persp 1993; 101:234-238.
  46. Winneke G. Structure and determinants of psychophysiological response to odorant/irritant air pollution. Ann New York Acad Sci 1992; 641:261-276.
  47. Bascom R. The upper respiratory tract: mucous membrane irritation. Environ Health Persp 1991; 95:39-44.
  48. Lin RY, LaFrance J, Sauter D. Hypersensitivity to common indoor aeroallergens in asthmatic patients. Ann Allergy 1993; 71:33-39.
  49. Gadon ME, Melius JM, McDonald GJ, Orgel D. New-onset asthma after exposure to the steam system additive 2-diethylaminoethanol. A descriptive study. J Occup Med 1994; 36:623-626.
  50. Infante-Revard C. Childhood asthma and indoor environmental risk factors. Am J Epidemiol 1993; 137:834-844.
  51. Hoffman RE, Wood RC, Kreiss K. Building-related asthma in Denver office workers. Am J Public Health 1993; 83:89-93.
  52. Ostro BD, Lipsett MJ, Mann JK, Wiener MB, Selner J. Indoor air pollution and asthma. Results from a panel study. Am J Respir Crit Care Med 1994; 149:1400-1406.
  53. Hoge CW, Reichler MR, Dominguez EA, Bremer JC, Mastro TD, Hendricks KA, Musher DM, Elliott JA, Facklam RR, Breiman RF. An epidemic of pneumococcal disease in an overcrowded in adequately ventilated jail. New Eng J Med 1994; 331:643-648.
  54. Neas LM, Dockery DW, Ware JH, Spengler JD, Ferris BG Jr., Speizer FE. Concentration of indoor particulate matter as a determinant of respiratory health in children. Am J Epidemiol 1994; 139:1088-1099.
  55. Guneser S, Atici A, Alparslan N, Cinaz P. Effects of indoor environmental factors on respiratory systems of children. J Tropocal Pediatri 1994; 40:114-116.
  56. Pilotto LS, Douglas RM. Indoor nitrogen dioxide and childhood respiratory illness. Aust J Public Health 1992; 16:245-250.
  57. Samet JM, Lambert WE, Skipper BJ, Cushing AH, Hunt WC, Young SA, McLaren LC, Schwab M, Spengler JD. Nitrogen dioxid and respiratory illness in children. Part I. Health outcomes. Research Report - Health Effects Institute 1993; 58:1-32.
  58. Lambert WE, Samet JM, Hunt WC, Skipper BJ, Schwab M, Spengler JD. Nitrogen dioxid and respiratory illness in children. Part II. assessment of exposure to nitrogen dioxide. Research Report - Health Effects Institute 1993; 58:33-50.
  59. Samet JM, Lambert WE, Skipper BJ, Cushing AH, Hunt WC, Young SA, McLaren LC, Schwab M, Spengler JD. Nitrogen dioxid and respiratory illness in infants. Am Rev Respir Dis 1993; 148:1258-1265.
  60. Samet JM. Indoor radon and lung cancer. Estimating the risks. Western J Med 1992; 156:25-29.
  61. Stidley CA, Samet JM. A review of ecologic studies of lung and indoor radon. Health Physics 1993; 65:234-251.
  62. Letourneau EG, Krewski D, Choi NW, Goddard MJ, McGregor RG, Zielinski JM, Du J. Case-control study of residential radon and lung cancer in Winniping, Manitoba, Canada. Am J Epidemiol 1994; 140:310-322.
  63. Biberman R, Lusky A, Schlesinger T, Margaloit M, Neeman E, Modan B. Increased risk for small cell lung cancer following residential exposure to low-dose radon: a pilot study. Arch Environ Health 1993; 48:209-212.
  64. WHO Working Group. Indoor air quality: a risk-based approach to health criteria for radon indoors. Summary report on a WHO Working Group Eilat, Isreal, 28 March, April 1993.
  65. Smith CJ, Sears SB, Walker JC, DeLuca PO. Environmental tobacco smoke: current assessment and future directions. Toxicol Pathol 1992; 20:289-303.
  66. Tweedie RL, Mengersen KL. Lung cancer and passive smoking: reconciling the biochemical and epidemiological approaches. Br J Cancer 1992; 66:700-705.
 
 

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