Alfheim I, Ramdahl T, Contribution of wood combustion to indoor air pollution as measured by mutagenicity in Salmonella and polycyclic aromatic hydrocarbon concentration, Environ. Mutagen 1984;6(2):121-130

Abstract: Samples of airborne particles have been collected in the same room when the room was heated by electricity and when heating was done by woodburning. These samples were compared with respect to mutagenic activity and concentration of polycyclic aromatic hydrocarbons (PAH). The effects of the various heating conditions were examined in the presence and absence of tobacco smoking. Whereas wood heating in an "airtight" stove was found to cause only minor changes in the concentration of PAH and no measurable increase of mutagenic activity of the indoor air, both these parameters increased considerably when wood was burned in an open fireplace, yielding PAH concentrations comparable to those of ambient urban air. Relatively high concentrations of moderately polar polycyclic aromatic hydrocarbon derivatives were also found in the indoor air when wood was burned in an open fireplace. Woodburning in the closed stove did, however, result in increased concentrations of mutagenic compounds and PAH on particles sampled in the vicinity of the house. The effects of wood burning in an open fireplace on the mutagenic activity of indoor air could still be considered moderate when compared to those resulting from tobacco smoking in the room. The extracts of particles collected when moderate smoking occurred were several times more mutagenic than samples from urban air collected close to streets with heavy traffic when measured in the Salmonella assay with strain TA98 with metabolic activation. >$/p>

Ardayfio Schandorf E, Women's health status in Africa -- environmental perspectives from rural communities, Health Care for Women International, 1993 Jul-Aug; 14(4): 375-86 (10 ref)

Abstract
Health research used to be the exclusive domain of clinicians and medical specialists, who focused attention on the biomedical causes of disease. Socioeconomic and environmental considerations that have important bearing on the ill health of rural African women were rarely integrated with the methodology constructed to investigate disease patterns. However, it is becoming increasingly clear that physical environmental factors and malnutrition have important effects on women's health in rural Africa. I validated this assumption in an empirical study of 441 people (n = 294 women) in 15 different rural localities in Ghana. Apart from women-specific problems relating to biological health needs during pregnancy, childbirth, and lactation, sexually transmitted diseases, abortion, and mental health, environmental factors had a great impact on women's well-being in the study area. Sixty-two percent of the women reported that the endemic disease malaria is the most prevalent disease as far as they were concerned. Other community and household health hazards were found; for example, cooking over an open fuel wood stove resulted in an almost 50% greater chance of stillbirth among pregnant women.

Betchley C., Koenig J.Q., Vanbelle G., Checkoway H., Reinhardt T., Pulmonary Function and Respiratory Symptoms in Forest Firefighters, American Journal of Industrial Medicine, 31(5):503-509, 1997 May

Abstract : This study evaluated effects on respiratory, health of forest firefighters exposed to high concentrations of smoke during their work shift. This is the first study of cross-shift respiratory effects in forest firefighters conducted on the job. Spirometric measurements and self-administered questionnaire data were collected before and after the 1992 firefighting season. Seventy-six (76) subjects were studied for cross-shift and 53 for cross-season analysis. On average, the cross-season data were collected 77.7 days after the last occupational smoke exposure. The cross-shift analysis identified significant mean individual declines in FVC, FEV(1), and FEF(25-75). The preshift to midshift decreases were 0.089 L, 0.190 L, and 0.439 L/sec, respectively, with preshift to postshift declines of 0.065 L, 0.150 L, and 0.496L/sec. Mean individual declines for FVC, FEV(1) and FEF(25-75) of 0.033 L, 0.104 L, and 0.275 L/sec, respectively, also were noted in the cross-season analysis. The FEV(1) changed significantly (p<0.05). The use of wood for indoor heat also was associated with the declines in FEV(1).Although annual lung function changes for a small subset (n=10) indicated reversibility of effect, this study suggests a concern for potential adverse respiratory effects in forest firefighters. (C) 1997 Wiley-Liss, Inc. [References: 32] Browning KG, Koenig JQ,

Butterfield, P, LaCava, G. Edumunston E, Penner, J. 1989. Woodstoves and indoor air: the effects on preschooler’s upper respiratory symptoms. J. Environ. Health 52:172-73. (L&K, Ref 14)

Boone PM, Rossman TG, Daisey JM. The genotoxic contribution of wood smoke to indoor respirable suspended particles. Environment International 1989 15:361-368.

Browning KG, Koenig JQ, Checkoway H, Larson, TV, Peirson WE., A questionnaire study of respiratory health in areas of high and low ambient wood smoke pollution, Pediatr. Asthma All. Immunol. 4:183-91, 1990

Churg A., Brauer M., Human Lung Parenchyma Retains PM2.5, American Journal of Respiratory & Critical Care Medicine, 155(6):2109-2111, 1997 June.

Abstract: There is extensive epidemiologic evidence that increased levels of the inhalable particulate fraction of air pollution (PM10) are associated with increased morbidity and mortality. The mechanisms of these effects are unknown, and the exact types and sizes of particles responsible are a matter of intense dispute. To obtain an idea of the sizes of particles retained in human lung parenchyma, we used analytical electron microscopy to count, size, and identify particles in the upper lobe apical segment parenchyma of autopsy lung tissue from 10 never-smoking long-term residents of Vancouver. The overall geometric mean particle diameter (CSD) was 0.38 mu m (2.4); within this broad distribution, silica and silicate particles had a geometric mean diameter of 0.49 mu m (2.2), whereas metals had a geometric mean diameter of 0.17 mu m (2.0). Ultrafine particles (those with diameter less than or equal to 0.1 mu m) constituted less than 5% of the total, and most of these were metals. Translation of these projected area diameters into aerodynamic diameters (d(a)) revealed that 96% of the particles had d, less than 2.5. These data indicate that human lung parenchyma effectively retains PM2.5, suggesting that attempts to determine the particles responsible for chronic particulate pollutant effects should concentrate on this size range. These data also suggest that several different type/size classes of particle are present in human parenchyma, but that ultrafine particles make up only a small fraction of the total. [References: 19]

Collings DA, Sithole SD, Martin KS, Indoor woodsmoke pollution causing lower respiratory disease in children, Trop Doct, 1990 Oct;20(4):151-155

Abstract: Suggested aetiological factors were evaluated in 244 consecutive children presenting with lower respiratory disease at Marondera Hospital, Zimbabwe. Data obtained from these children were compared with information obtained from 500 children seen at the local well baby clinic. There were no differences in the prevalence of malnutrition, breast feeding, overcrowding, poor housing conditions and poverty in these two groups of children. A significant association was identified between lower respiratory disease and exposure to atmospheric woodsmoke pollution in young children. Air sampling within the kitchens of 40 children revealed levels of atmospheric pollution far in excess of the WHO recommended exposure limit. Elevated carboxyhaemoglobin concentrations confirmed childhood smoke inhalation. We suggest that in many Third World communities a chemical pneumonitis resulting from the inhalation of noxious constituents of woodsmoke predisposes to lower respiratory disease in children.

Cooper J.A., Environmental Impact of Residential Wood Combustion Emissions and its Implications, Air Pollution Control Association Journal, 30 (8), 855-861, 1980 Aug.

Abstract: Currently available information suggests a substantial environmantal impact from residential wood combustion emissions. Air pollution from this source is widespread and increasing. Current ambient measurements, surveys, and model predictions indicate winter respirable ( < 2 mm) emissions from residential wood combustions can easily exced all other sources. Both the chemical potency and deliverability of the emissions from this source are of concern. The emissions are almost entirely in the inhalable size range, and contain toxic and priority pollutants, carcinogens, co-carcinogens, cilia toxic, mucus coagulating agents, and other respiratory irritants sych as phenols, aldehydes, etc. This source is contributing substantially to the non-attainment of current particulate, carbon monoxide, and hydrocarbon ambient air standards, and will almost certainly have a significant impact on potential future standards such as inhalable particulates, visibliity, and other chemically specific standards. Emission from this growing source is likely to require additional expenditures by industry for air pollution control equipment in non-attainment areas.

Daigler G.E, Markello S.J, Cummings K.M, The effect of indoor air pollutants on otitis media and asthma in children, Laryngoscope 1991 Mar;101(3):293-296 Department of Pediatrics, State University of New York, Buffalo.

Abstract: This case-control study investigated the possible association between home environmental air pollutants and their effect on otitis media and asthma in children. Patients with physician-diagnosed otitis (n = 125, 74% response), with asthma (n = 137, 80% response), and controls (n = 237, 72% response) from a private pediatric practice seen between October 1986 and May 1987 were studied. A questionnaire inquired about housing characteristics (i.e., age, insulation, heating system) and sources of indoor air pollution such as cigarette smoking, use of woodburning stoves, household pets, etc. Analysis of the responses confirmed previous findings of significant relationships between maternal smoking (P = .021), and the presence of pets (P = .034) and the occurrence of asthma. A newly reported relationship between exposure to woodburning stoves and the occurrence of otitis (P less than .05) was reported. This implicates yet another risk factor (wood burning) in the etiology of otitis media.

Dean BS, Lopez G, Krenzelok EP, Environmentally-induced methemoglobinemia in an infant, J Toxicol Clin Toxicol 1992;30(1):127-133 Pittsburgh Poison Center, Children's Hospital of Pittsburgh, Pennsylvania 15213-2583.

Abstract: Acquired methemoglobinemia results from the exposure to various chemicals and drugs able to oxidize hemoglobin at a rate exceeding the normal enzymatic capacity for hemoglobin reduction. Levels of methemoglobin exceeding 60-70% may be associated with coma and death. We describe a case of complete, uneventful recovery involving a 10 week-old infant who presented to the Emergency Department with profound sudden onset of cyanosis, irritability, metabolic acidosis, and a lethal methemoglobin level of 71.4%. Intravenous administration of 12 mg methylene blue resulted in immediate resolution of the cyanosis and reduction of measured methemoglobin to 1.3%. The carboxyhemoglobin was negative. Sodium bicarbonate successfully corrected the acidosis. RBC reductase measurement was within normal limits, ruling out congenital methemoglobinemia. Family history revealed a wood-burning stove which emitted pine tar fumes as the potential environmental methemoglobin-producing source. The infant's cradle was situated five feet from the stove. The infant was discharged on day three of hospitalization with a methemoglobin level of 0.2%.

Dennis RJ, Maldonado D, Norman S, Baena E, Martinez G, Woodsmoke exposure and risk for obstructive airways disease among women, Chest 1996 Jan;109(1):115-119 Pontificia Universidad Javeriana, Bogota, Colombia.

Abstract: OBJECTIVE: To investigate if exposure to firewood smoke and other indoor pollutants is a potential risk factor for obstructive airways disease (OAD) among women in Bogota in whom cigarette smoking and other known risk factors may not be the most frequent. DESIGN AND SETTING: We conducted a hospital-based case-control study to identify risk factors for OAD among women in Bogota. An interview was conducted using a modified questionnaire recommended by the American Thoracic Society for epidemiologic studies. PATIENTS: We compared 104 OAD cases with 104 controls matched by hospital and frequency matched by age. ANALYSIS: The odds ratio (OR) was used as the basic statistic to evaluate risk. Multivariate analysis (MA) was conducted by the Mantel-Haenszel procedure and by logistic regression. MAIN RESULTS: Univariate analysis showed that tobacco use (OR = 2.22; p < 0.01), wood use for cooking (OR = 3.43; p < 0.001), passive smoking (OR = 2.05; p = 0.01), and gasoline use for cooking (OR = 0.52; p = 0.02) were associated with OAD. Trends for years of tobacco use and years of wood cooking were present (p < 0.05). After MA, variables remained significant except gasoline use. CONCLUSIONS: This study showed that among elderly women of low socioeconomic status in Bogota, woodsmoke exposure is associated with the development of OAD and may help explain around 50% of all OAD cases. The role of passive smoking remains to be clarified. This work may set the basis for interventional studies in similar settings.

Ellegard A., Cooking Fuel Smoke and Respiratory Symptoms Among Women in Low-Income Areas in Maputo, Environmental Health Perspectives, 104(9):980-985, 1996 Sep.

Abstract: The association between exposure to air pollution from cooking fuels and health aspects was studied in Maputo, Mozambique. Almost 1200 randomly selected women residing in the suburbs of Maputo were interviewed and 218 were monitored for air pollution. The fuels most commonly used were wood, charcoal, electricity and liquified petroleum gas (LPG). Wood users were exposed to significantly higher levels of particulate pollution during cooking time (1200 mu g/m3) than charcoal users (540 mu g/m(3)) and users of modern fuels (LPG and electricity) (200-380 mu g/m(3)). Wood users were found to have significantly more cough symptoms than other groups. This association remained significant when controlling for a large number of environmental variables. There was no difference in cough symptoms between charcoal users and users of modern fuels. Other respiratory symptoms such as dyspnea, wheezing, and inhalation and exhalation difficulties were not associated with wood use. Reducing wood use would Likely improve acute respiratory health effects in wood users and possibly improve the ambient air pollution conditions in Maputo. To reduce the health impact of wood smoke exposure, it appears that the least costly and quickest method would be to encourage charcoal use to a greater extent, high carbon monoxide levels would have to be addressed. Turning to modern fuels is beyond the means of most these households in the short term and could not be shown to be more effective. [References: 20]

EPA NSW. Environment Protection Authority New South Wales. Air Pollution from solid fuel home heaters. Jan. 1996.

Gharaibeh NS., Effects of Indoor Air Pollution on Lung Function of Primary School Children in Jordan, Annals of Tropical Paediatrics, 16(2):97-102, 1996 June

Abstract: Environmental exposure to tobacco smoke and contaminants from unvented cooking stoves has been linked to impaired pulmonary function and respiratory diseases. These risk factors exist to a greater extent in developing countries and, in the case of exposure to tobacco smoke, they are reported to be increasing. In this study, pulmonary function studies were performed on 1905 children in Jordan. The effect of exposure to these environmental factors on respiratory function was analyzed. A significant negative impact was found with regard to environmental exposure to both passive smoking and wood and kerosene unvented cooking stoves. The mean values of lung function in children exposed and not exposed to passive smoking were, respectively, FVC (L): 1.29-1.49; FEV(1) (L): 1.2-1.4; FEF(25-75) (L/S): 1.84-2.24; PEFR (L/S): 2.6-3.21, and to wood and kerosene were FVC (L): 1.02-1.32; FEV(1) (L): 0.91-1.25; FEF(25-75) (L/S): 1.24-1.86; PEFR (L/S): 1.67-2.64. This is a major problem in developing countries because of the increasing incidence of smoking and the high exposure to pollution risk factors. [References: 15]

Godleski J., Sioutas C., Katler M., Koutrakis P., Death from inhalation of concentrated ambient air particles in animal models of pulmonary disease, Proceedings of the Second Colloquium on Particulate Air Pollution and Human Health, Utah, 1996 May

Abstract
Epidemiologic studies have found increased mortality associated with particulate air pollution. To test the biologic plausibility of this association, normal rats, rats with monocrotyline-induced pulmonary inflammation (50 mg/kg SC), and rats with SO2 induced chronic bronchitis (250 ppm SO2, 6 wks) were expose to concentrated air particles (CAPS) or filtered air for 3 consecutive days, 6 hours/day. The concentrating system of Sioutas et al, (Env Hlth Perspect 1995, 103:171) was used.

Deaths occured during exposure and overnight. Inflammation was found in groups with disease, but animals exposed to CAPS exhibited increases in inflammatory parameters and broncho-constriction. Broncho-constriction, visible bucklling of the epithelium, was enumerated in all groups comparing the number of constricted airways in animals dying spontaneously with those who survived exposures but were killed afterwards. Animals with chronic bronchitis had the most evidence of airway constriction. In comparing death versus killed, broncho-constriction was significantly increased in the disease groups (monocrotyline p = 0.007; chronic bronchitis p = 0.02). Thus, ambient particle inhalation can cause death in rats with disease, and inflammation as well as airway constriction appear to be important in the response.

Guneser S, Atici A, Alparslan N, Cinaz P, Effects of indoor environmental factors on respiratory systems of children, J Trop Pediatr 1994 Apr;40(2):114-116 Cukurova University Medical Faculty, Department of Pediatrics, Adana, Turkey.

Abstract: Effects of indoor environmental factors on children's respiratory system and pulmonary function tests were investigated in this study. A total of 617 primary school children aged between 9-12 years were included. A standard questionnaire, which includes questions about respiratory symptoms and illness, indoor environmental determinants, family history of respiratory diseases, and smoking habits of the parents, was sent to homes of all children and information was obtained from parents. Children with a family history of asthma, bronchitis, or other chest troubles suffered morning and day/night coughs, shortness of breath, wheezing and asthma, bronchitis, or pneumonia more frequently. Children whose mothers smoked complained of blocked-runny nose and sinusitis more frequently. Pulmonary function levels were diminished in passive smokers and in children whose houses were heated by a wood-burning stove. As a result, passive smoking, using a wood-burning stove for heating, and family history of respiratory diseases are to be considered risk factors for the respiratory system.

Heumann M., Foster L.R., Johnson L, Kelly L., Woodsmoke Air Pollution and Changes in Pulmonary Function Among Elementary School Children, Air & Waste Management Association 84th Annual Meeting & Exhibition, Vancouver, British Columbia, 1991 June.

Hamada G.S, Kowalski L.P, Murata Y, Matsushita H, Matsuki H, Wood stove effects on indoor air quality in Brazilian homes: carcinogens, suspended particulate matter, and nitrogen dioxide analysis, Tokai J. Exp. Clin. Med. 1992 Oct;17(3-4):145-153

Abstract: The effects of wood burning stoves on indoor air quality was investigated in a rural community of southern Brazil, during the winter season of 1991. The concentrations of polycyclic aromatic hydrocarbons (PAHs), nitrogen dioxide (NO2) and suspended particulate matter (SPM) were assessed in houses with wood stoves and the results compared with levels found in houses with gas stoves. Strikingly higher (p < 0.01) levels of PAHs, and much higher (p = 0.07) levels of SPM were found in the kitchens with wood stoves. In contrast, NO2 concentrations in the kitchen as well in personal exposure, were found to be slightly higher in houses with gas stoves. All these differences were minimally affected by smoking, outdoor air pollution or other emissions from indoor combustion products. These findings appear to support the hypothesis that domestic wood burning stoves are risk factors for some upper digestive and respiratory tract cancers in Brazil.

Hogg J. C, Bronchiolitis obliterans and wood-burning stoves, Canadian Medical Association Journal,1997 Apr 15;156(8):1147-1148 Editorial, Comments on: Can Med Assoc J 1997 Apr 15;156(8):1171-3

Abstract The author reviews the features of bronchiolitis obliterans, a potentially fatal condition first described in 1901. There are 2 main types of the disease. In the "classic" type, polyps of granulation tissue form in the bronchiolar lumen, typically after a massive exposure to toxic fumes. In the "peribronchiolar" type an inflammatory response contricts the lumen but leaves the mucosa relatively intact; this is usually associated with a chronic exposure and progresses more slowly than the classic type. The author comments on the case report by Dr. David T. Janigan and colleagues in this issue of classic bronchiolitis obliterans in a man who used a wood-burning stove to dispose of construction materials.

Honicky RE, Osborne JS 3d, Akpom CA, Symptoms of respiratory illness in young children and the use of wood-burning stoves for indoor heating, Pediatrics 1985 Mar;75(3):587-593

Abstract: The occurrence of symptoms of respiratory illness among preschool children living in homes heated by wood-burning stoves was examined by conducting an historical prospective study (n = 62) with an internal control group (matched for age, sex, and town of residence). Exposures of subjects were not significantly different (P greater than .05) with respect to parental smoking, urea-formaldehyde foam insulation, and use of humidifiers. The control group made significantly greater use of gas stoves for cooking whereas the study group made greater use of electric stoves for cooking and of air filters (P less than .05). Only one home used a kerosene space heater. During the winter of 1982, moderate and severe symptoms in all categories were significantly greater for the study group compared with the control group (P less than .001). These differences could not be accounted for by medical histories (eg, allergies, asthma), demographic or socioeconomic characteristics, or by exposure to sources of indoor air pollution other than wood-burning stoves. Present findings suggest that indoor heating with wood-burning stoves may be a significant etiologic factor in the occurrence of symptoms of respiratory illness in young children.

Johnson KG, Gideon RA, Loftsgaarden DO, Montana air pollution study: children’s health effects. J. Official Stat. 5:391-407, 1990.

Koenig J.Q, Larson T.V, Hanley Q.S, Rebolledo V, Dumler K, Checkoway H, Wang S.Z, Lin D, Pierson W.E, Pulmonary function changes in children associated with fine particulate matter, Environ Res 1993 Oct;63(1):26-38 , Department of Environmental Health, University of Washington, Seattle 98195.

Abstract: During winter months many neighborhoods in the Seattle metropolitan area are heavily affected by particulate matter from residential wood burning. A study was conducted to investigate the relationship between fine particulate matter and pulmonary function in young children. The subjects were 326 elementary school children, including 24 asthmatics, who lived in an area with high particulate concentrations predominantly from residential wood burning. FEV1 and FVC were measured before, during and after the 1988-1989 and 1989-1990 winter heating seasons. Fine particulate matter was assessed using a light-scattering instrument. Analysis of the relationship between light scattering and lung function indicated that an increase in particulate air pollution was associated with a decline in asthmatic children's pulmonary function. FEV1 and FVC in the asthmatic children dropped an average of 34 and 37 ml respectively for each 10(-4) m-1 increase in sigma sp. This sigma sp increase corresponds to an increase in PM2.5 of 20 micrograms/m3. It is concluded that fine particulate matter from wood burning is significantly associated with acute respiratory irritation in young asthmatic children.

Kou Y.R., Lai C.J., Hsu T.H., Lin Y.S., Involvement of Hydroxyl Radical in the Immediate Ventilatory Responses to Inhaled Wood Smoke in Rats, Respiration Physiology, 107(1):1-13, 1997 Jan.

Abstract: Spontaneous inhalation of wood smoke (similar to 6 mi) via a tracheostomy immediately triggered either a slowing of respiration (SR, n = 51) or an augmented inspiration (AI, n = 32) in 83 anesthetized Sprague-Dawley rats studied. To investigate the involvement of hydroxyl radical (OH.) in evoking these immediate smoke-induced ventilatory responses, smoke challenges were repeated following intravenous infusion (0.05 ml/min for 20 min) of saline vehicle, dimethylthiourea (DMTU, 500 mg/kg), deferoxamine (DEF, 20 mg/kg), or iron-saturated DEF (DEF+Fe, 20 mg/kg). DMTU is a scavenger for OH.. DEF is an iron-chelator which prevents the formation of OH., whereas DEF saturated with iron results in the loss of its iron-chelating properties. In the vehicle group, both the SR (n = 8) and the AI (n = 7) were unaffected by the pretreatment. However, in the DMTU group, the SR (n = 23) was abolished in seven and attenuated in 16 rats, while the AI (n = 10) was eliminated in eight and unaffected in two rats. In the DEF group, the SR (n = 12) was abolished in three and attenuated in nine rats, while the AI (n = 8) was eliminated in six and unaffected in two rats. In contrast, in the DEF + Fe group, both the SR (n = 8) and the AI (n = 7) were not attenuated by the pretreatment. These results suggest that an increase in OH. burden following smoke inhalation is actively involved in evoking the acute irritant effects of wood smoke on breathing in rats. (C) 1997 Elsevier Science B.V. [References: 25]

Public-health impact of outdoor and traffic-related air pollution: a European assessment
N Kunzli, R Kaiser, S Medina, M Studnicka, O Chanel, P Filliger, M Herry, F Horak Jr, V Puybonnieux-Texier, P Quenel, J Schneider, R Seethaler, J-C Vergnaud and H Sommer Lancet 2000; 356: 795-801

The authors estimate the effects of air pollution on public health and its part in causing sickness and death in Europe. Their focus is on the economic aspects of this environmental factor, which are considerable.
© COPYRIGHT 2000 The Lancet Ltd.

SUMMARY

Background Air pollution contributes to mortality and morbidity. We estimated the impact of outdoor (total) and traffic-related air pollution on public health in Austria, France, and Switzerland. Attributable cases of morbidity and mortality were estimated.

Methods Epidemiology-based exposure-response functions for a 10 [micro]g/m3 increase in particulate matter (PM10) were used to quantify the effects of air pollution. Cases attributable to air pollution were estimated for mortality (adults ³ 30 years), respiratory and cardiovascular hospital admissions (all ages), incidence of chronic bronchitis (adults ³ 25 years), bronchitis episodes in children (<15 years), restricted activity days (adults ³ 20 years), and asthma attacks in adults and children. Population exposure (PM10) was modelled for each km2. The traffic-related fraction was estimated based on PM10 emission inventories.

Findings Air pollution caused 6% of total mortality or more than 40000 attributable cases per year. About half of all mortality caused by air pollution was attributed to motorised traffic, accounting also for: more than 25000 new cases of chronic bronchitis (adults); more than 290000 episodes of bronchitis (children); more than 0.5 million asthma attacks; and more than 16 million person-days of restricted activities.

Interpretation This assessment estimates the public-health impacts of current patterns of air pollution. Although individual health risks of air pollution are relatively small, the public-health consequences are considerable. Traffic-related air pollution remains a key target for public-health action in Europe. Our results, which have also been used for economic valuation, should guide decisions on the assessment of environmental health-policy options.

Lal K, Dutta KK, Vachhrajani KD, Gupta GS, Srivastava AK, Histomorphological changes in lung of rats following exposure to wood smoke, Indian J Exp Biol, 1993 Sep;31(9):761-764

Abstract: Rats were exposed to repeated, intermittent exposure to smoke generated from combustion of 1g wood/15 min, total period for 75 min daily under dynamic exposure conditions, over a period of 15, 30 and 45 days. First 15 days exposure caused mild bronchiolitis, hyperplasia and hypertrophy of bronchiolar epithelial lining cells, some necrosed lining cells desquamated into lumens, congestion of parenchymatous blood vessels, oedema, hyperplasia of lymphoid follicles, peribronchiolar and perivascular infiltration of polymorphonuclear cells, and mild emphysema. These lesions progressed further during 30 and 45 days of exposure, though emphysematous changes remain constant. By 30 days and 45 days, hyperplastic and hypertrophic changes of bronchioles become quite marked, with mononuclear cells infiltration and alveolar septa thickening. Hematological studies show marginal alterations in hemoglobin levels, ESR, PCV and TLCS during 15 days, where as significant changes in eosinophil were observed during 30 and 45 days, and ESR during 45 days only. The results indicate progressive pathomorphological pulmonary lesions with subsequent exposure to wood smoke in controlled conditions.

Larson T.V., Koenig J.Q., Wood Smoke - Emissions and NonCancer Respiratory Effects, [Review], Annual Review of Public Health, 15:133-156, 1994.

Abstract
In conclusion, this review reveals much about the constituents and fate of wood smoke but not enough about the health effects. Animal toxicological studies show that wood smoke exposure can disrupt cellular membranes, depress macrophage activity, destroy ciliated and secretory respiratory epithelial cells, and cause aberrations in biochemical enzyme levels. With respect to the human epidemiological data, the literature summarized in Table 4 shows a coherence of the data from young children, with 7/8 studies especially in children with asthma, reporting increased respiratory symptoms, lower respiratory infection, and decreased pulmonary function as a result of exposure to wood smoke. As Bates (6) has discussed, coherence of the data, although not amenable to statistical tests, carries the weight of linkage and plausibility. These adverse respiratory effects associated with wood smoke exposure also comply with many of Brandon Hill's aspects of association necessary to establish causation (40). There is strength of association, consistency (7/8 studies showing positive associations), temporality, plausibility, coherence, and analogy (using ETS exposure; 70, 94). A biological gradient has not been shown, although one is suggested in the study of pulmonary function in wildfire fighters. We conclude that the preponderance of the data suggest a causal relationship between elevated wood smoke levels and adverse respiratory health outcomes in young children.

Lewtas J., Zweidinger R.B., Cupitt L., Mutagenicity, Tumorigenicity and Estimation of Cancer Risk from Ambient Aerosol and Source Emissions from Woodsmoke and Motor Vehicles, Air and Waste Management Association 84^th Annual Meeting & Exhibition, Vancouver, British Columbia, 1991 June.

Lewis PR, Hensley MJ, Wlodarczyk J, Toneguzzi RC, Westley-Wise VJ, Dunn T, Calvert D. Outdoor air pollution and children's respiratory symptoms in the steel cities of New South Wales. Med J Aust. 1998 Nov 2;169(9):459-63.
Newcastle Environmental Toxicology Research Unit, University of Newcastle, NSW. plewi@doh.health.nsw.gov.au

OBJECTIVE: To investigate the relationship between outdoor air pollution and the respiratory health of children aged 8 to 10 years.

DESIGN: A cross-sectional survey (between October 1993 and December 1993) of children's health and home environment. Summary measures of particulate pollution (levels of particles with an aerodynamic diameter less than 10 microns [PM10] each 6th day) and SO2 (daily mean and maximum hourly values) were estimated for each area (using air quality monitoring station data from July 1993 to June 1994).

SETTING AND SURVEY
PARTICIPANTS: Parents of 3023 primary school children (Years 3, 4 and 5) from industrial and non-industrial areas with air quality monitoring stations in the Hunter and Illawarra regions of New South Wales.
MAIN OUTCOME MEASURES: Reported occurrence of four or more chest colds, four or more attacks of wheezing, and night-time cough without a cold for more than two weeks, all within the previous 12 months.

RESULTS: 77% response rate, ranging by area from 66% to 88%. The average annual outdoor air pollution for the nine areas was 18.6-43.7 micrograms/m3 for PM10 and 0.16-0.90 parts per hundred million for SO2. The proportion of children reported to have the main outcome symptoms were: chest colds, 3.0%-9.7%; night cough, 12.3%-30.5%; and wheeze, 3.4%-11.3%. There was no significant association with SO2, but a significant increase in the odds of symptoms per 10 micrograms/m3 increase in PM10 on chest colds (odds ratio [OR], 1.43; 95% confidence interval [CI], 1.12-1.82) and night-time cough (OR, 1.34; 95% CI, 1.19-1.53), but not wheeze. Passive smoking was significantly associated with chest colds but not with the other symptoms. Maternal allergy was associated with all three respiratory symptoms, most strongly with wheeze.

CONCLUSION: These results provide evidence of health effects at lower than expected levels of outdoor air pollution in the Australian setting. They also suggest differences in contributions of environmental and hereditary factors to cough and chest colds compared with wheeze.