Effects Of Indoor Air Pollution Research Articles

Evaluation of mucociliary clearance among women using biomass and clean fuel in a periurban area of Chennai: A preliminary study

Background:Nasal mucociliary clearance (NMC) plays a crucial role in the defense of the airways against inhaled substances and is affected by various factors. The effect of particulate matter on NMC in women using biomass fuel has not been well studied.Aim:This cross-sectional study was conducted to assess the NMC time in biomass fuel users and compare it with that of clean fuel users.Materials and Methods:NMC time and Peak Expiratory Flow Rate (PEFR) were determined in women of age ranging from 18 to 45 years using biomass fuel (n=30) and clean fuel (n=30). The time taken to perceive the sweet taste, following placement of saccharin 1 cm behind the anterior end of inferior turbinate was recorded as NMC time. PEFR was measured using mini-Wright peak flow meter. Comparison between groups was analyzed using t-test and ANOVA in R statistical software.Results:NMC time was significantly prolonged in biomass fuel users (765.8 ± 378.16 s) in comparison to clean fuel users (545.4 ± 215.55 s). PEFR was significantly reduced (319.3 l/min) in biomass fuel users compared to clean fuel users (371.7 l/min). Women from lower socioeconomic status, lower literacy status, older undernourished women and women cooking for>15 years had prolonged Saccharin Transit Time (STT) and reduced PEFR.Conclusions:This study highlights the effects of indoor air pollution on respiratory defense mechanism. This simple noninvasive, inexpensive, screening test can be used as an early indicator of respiratory damage caused by exposure to air pollutants.

The Assessment of Survey on the Indoor Air Quality of Children Care Centers in South Korea

PP-30-143 Background/Aims: Children in child care facilities may spend 100% of their day indoors, yet indoor air can be more harmful to their health than the air outdoors. The effects of indoor air pollution are of special interest in relation to respiratory health and allergic disorders including asthma. Here, the main concern centers around the question as to what extent different exposures give rise to different effects and to what extent these effects in turn translate to health risks. Methods: Therefore, this study was performed to investigate the characteristics of IAQ (indoor air quality) in 70 children care centers in South Korea. We measured indoor air pollutants (PM10, CO2, HCHO, total bacteria colony [TBC], and TVOCs) and physical factors (temperature and relative humidity) with necessary of management for IAQ in children care centers. Results: This study is conducted as a part of efforts to provide a foundational data for further relative researches on management of IAQ of children care centers. Conclusion: Therefore, we suggest that country plan for management of IAQ in children care centers should be established through long-term and continuous investigation for assessment on IAQ in children care centers and health risk assessment for children.

Indoor Environmental Quality - Standards for Protection of Occupants’ Safety, Health and Environment

Buildings represent a major investment, not just at the design and construction stage, but throughout their service lives because of on-going operational and maintenance. Increasingly owners and occupiers are becoming aware of the importance to maintain an adequate built environmental quality that is attractive and acceptable for the intended occupants. Achieving occupant comfort, including consideration of ventilation, thermal and glare and prevention of adverse health risks can have consequent benefits for occupant productivity and satisfaction, which could maximise the letting/selling potential of the property. Creating and maintaining a comfortable, healthy, efficient and cost-effective indoor environment is a complex task that involves understanding the capabilities and interactions of a range of systems, technologies and building materials as well as occupant requirements. There is a need to form an overall strategy for building design and management to incorporate occupant needs within the concept of ‘sustainable development’. Indoor air scientists have long argued that control of emissions from the building materials and consumer products used in buildings should be an important part of policies and actions to protect public health from the adverse effects of indoor air pollution [1–4]. The response from product manufacturers and regulators in the past can be described as variable and on the whole disappointing. In Europe for example a few countries and some producers have made important steps whereas others have yet to effectively address indoor air quality (IAQ). The issue is now rising up the agenda particularly because of concerns that changes to building design to adapt to the expected effects of climate change could have an adverse impact on IAQ [5,6]. However, there is a continuing need to raise awareness of the issue; for example the UK government’s Code for Sustainable Homes has a section on ‘health and well being’ of occupants without mention of IAQ. Increasingly, buildings are required to be highly air-tight and insulated to meet the ‘‘zero-carbon’’ objectives of governments and this has implications for indoor environmental quality [7]. To minimise the occupants’ exposure risks to indoor pollutants and to enhance environmental quality of buildings, there is a need to consider guidelines [8] and standards for buildings including criteria for ventilation, materials emissions and IAQ criteria for indoor air pollutants such as total VOCs (TVOC), benzene, formaldehyde, carbon monoxide, nitrogen dioxide, microparticulates and polyaromatics [9], as well as microbial contaminants, for example toxic moulds [10]. The scientific literature contains many reports of IAQ problems arising from the use of particular products that release chemicals causing odour and irritation or resulting in an

Environmental and occupational allergies

Airborne allergens are the major cause of allergic rhinitis and asthma. Daily exposure comes from indoor sources, chiefly at home but occasionally at schools or offices. Seasonal exposure to outdoor allergens, pollens, and molds is another important source. Exposure to unusual substances at work causes occupational asthma, accounting for about 5% of asthma in adults. Indoor and outdoor air pollutants trigger airway inflammation and increase the severity of asthma. Diesel exhaust particles increase the production of IgE antibodies. Identification and reduction of exposure to allergens is a very important part of the management of respiratory allergic diseases. The first section of this chapter discusses domestic allergens, arthropods (mites and cockroaches), molds, and mammals (pets and mice). Indoor humidity and water damage are important factors in the production of mite and mold allergens, and discarded human food items are important sources of proliferation of cockroaches and mice. Means of identifying and reducing exposure are presented. The second section discusses outdoor allergens: pollens and molds. The particular plants or molds and the amount of exposure to these allergens is determined by the local climate, and local pollen and mold counts are available to determine the time and amount of exposure. Climate change is already having an important effect on the distribution and amount of outdoor allergens. The third section discusses indoor and outdoor air pollution and methods that individuals can take to reduce indoor pollution in addition to eliminating cigarette smoking. The fourth section discusses the diagnosis and management of occupational asthma.

The expression of nerve growth factor in mice lung following low-level toluene exposure

To clarify the effect of indoor air pollutants on nerve growth factor (NGF) production in lung, male C3H/HeN mice were exposed to filtered air (control) or toluene at levels of 0.9ppm, 9ppm, or 90ppm for 30min via nose-only inhalation on days 0, 1, 2, 7, 14, 21, 28, 35, 42, 49 and 56. As an allergic mouse model, some mice (n=24) were immunized with ovalbumin. Lungs from each mouse were collected to determine NGF and related receptor expressions using real-time reverse transcription polymerase chain reaction (RT-PCR) analysis. NGF and TrkA mRNAs were increased in the lungs of the immunized mice following exposure to 9ppm toluene (n=6) (P<0.05ppm vs. 0ppm). Remarkably increased NGF-positive bronchiolus and alveolar epithelium cells were observed in 9ppm toluene-exposed, immunized mice. To determine NGF mediating signaling, we also examined mRNA expression of neurotrophin receptor p75 (p75NTR) and oxidative stress marker, heme oxygenase (HO)-1 in the lung. There is no difference in the expressions of p75NTR and HO-1 between toluene-exposed and control mice. The expression of CCL2 and CCL3 mRNAs was significantly elevated in 9ppm toluene-exposed, immunized mice. These findings suggest that the exposure with volatile organic compounds enhanced NGF expression and airway inflammation stronger in allergic individuals than in healthy individuals.

Effect of Indoor Air Pollution from Biomass Fuel Use on Argyrophilic Nuclear Organizer Regions in Buccal Epithelial Cells

This study investigated the effect of indoor air pollution from biomass-fuel use on the expression of argyrophilic nucleolar organizer regions (AgNORs), an indicator of ribosome biosynthesis, in epithelial cells of oral mucosa. AgNORs were evaluated using cytochemical staining in 62 nonsmoking indian women (median age, 34 years), who cooked exclusively with biomass, and 55 age-matched women, who were from a similar neighborhood and cooked with relatively clean liquefied petroleum gas (LPG). Concentrations of particulate pollutants in indoor air were measured using a real-time aerosol monitor. Compared to the LPG-using controls, biomass-fuel users showed a remarkably increased number of AgNOR dots per nucleus (6.08 +/-2.26 vs 3.16 +/-0.86, p < 0.001), AgNOR size (0.85 +/-0.19 vs 0.53 +/-0.15 mum2, p < 0.001), and percentage of AgNOR-occupied nuclear area (4.88 +/-1.49 vs 1.75 +/-0.13%, p < 0.001). Biomass-using households had 2 to 4 times more particulate pollutants than that of LPG-using households. The changes in AgNOR expression were positively associated with PM10 and PM2.5 levels in indoor air after controlling for potential confounders such as age, kitchen location, and family income. Thus, biomass smoke appears to be a risk factor for abnormal cell growth via upregulation of ribosome biogenesis.

Indoor Air Pollution and Respiratory Function of Children in Ashok Vihar, Delhi: An Exposure-Response Study

The objective of this study was to investigate the effects of indoor air pollution on respiratory function of children (aged 7-15 years). The study took place at Ashok Vihar, an urban locality in the northwest part of Delhi during the summer months of June and July 2004. The team did house visits. The questionnaire, administered at the house itself, asked about the history of smoking in the family, type of cooking fuel used, duration of cooking, ventilation and lighting at the cooking place, and other confounders. In total, 441 children (59% male, 41% female) between ages 7 and 15 years were considered for the study, and a detailed profile was collected. Clinical examination with special reference to respiratory system was done. Pulmonary function tests/peak expiratory flow rates of each child were measured. Indoor air pollutant (suspended particulate matter, SO(2), NO(2)) was measured, and the effect of these pollutants on the children's respiratory function was analyzed. The respiratory health profile suggests that children had cough, sputum production, shortness of breath, wheezing, common cold, and throat congestion. Indoor SO(2) , NO(2), and suspended particulate matter levels were high in houses where there was a family history of smoking. SO(2) level was significantly high according to occupancy per room. NO(2) and suspended particulate matter levels were significantly high in houses where children had respiratory problems. It is concluded that indoor air pollution had an association with respiratory function of children.

Social perceptions about a technological innovation for fuelwood cooking: Case study in rural Mexico

The widespread use of traditional biomass fuels in open fires in developing countries brings about serious health effects, besides high fuelwood consumption. A technological innovation—i.e., improved cookstoves—reduce fuel consumption and address the health effects of indoor air pollution. Implementation projects have been conducted worldwide, but have frequently faced very low success rates. Different demographic and socio-economic factors have been analysed to explain low rates but there are almost no studies that try to understand, from the users’ perspective, the factors involved when choosing among different cooking technologies. Through a qualitative methodological approach we documented the adoption of improved cookstoves through the implementation programme of a Mexican NGO. Results showed that although the programme raised public awareness, the improved cookstoves did not reach the poorest sector. The socioeconomic level was found positively correlated with the adoption of the improved cookstoves, but neither the age nor the educational levels were. Payment of the stove did not seem to be an adoption factor. Differences among individual users were more significant than differences between communities. Finally as men are the principal fuelwood harvesters, they should be considered as an important group in diffusion programs.

Indoor exposure to chemical and biological agents and health efects in primary school children

Abstract The aim of this study has been to estimate effects of indoor air pollutants on children’s health. An anamnestic retrospective study was done on 1074 children aged between 7 and 11 years old who lived in Nis (Serbia). An original questionnaire was used in an interview between training physicians and children’s parents. Interview data were processed by using Microsoft Excel and Epiinfo 6. The investigation determined that children who were more often exposed to combustion by-products had respiratory and nonspecific symptoms. Parental smoking was strongly associated with wheezing, bronchitis, headache and fatigue. There was no association between health and keeping pets, apart from partial nasal congestion. Presence of insects (e.g., cockroaches) and rats in households was a significant risk factor for all symptoms and diseases estimated except for asthma and pneumonia. Homes abundant in textiles were the cause of nasal congestion, wheezing and fatigue in children. Old mattresses were associated with respiratory symptoms, bronchitis, and nonspecific symptoms. It has been concluded that indoor air quality plays a major role in children’s health. Sources of indoor air pollution are present in every home. Being aware of the risks associated with indoor air quality problems, consequently, leads to their mitigation.

Biomass Smoke Exposure Among Guatemalan Infants Participating in a Randomized Trial of Chimney Stoves

SS6-08 Objectives: As part of a randomized trial to study the effect of indoor air pollution on acute lower respiratory infections (ALRI) among Guatemalan infants, we aimed to assess the effectiveness of the plancha improved wood-burning stove as an exposure-reduction intervention and estimate child-specific longitudinal exposures during the first 18 months of life. Methods: Five hundred thirty-four households with young infants participated in the trial, with half assigned to the intervention arm and half continuing to use their traditional open fire until the end of the trial. Personal carbon monoxide (CO) exposures were used as a proxy for biomass smoke exposures because there were no other important local sources of CO. Gastec passive diffusion tubes were worn by the infants for 48 hours roughly every 3 months until they were 18 months old. A total of 2190 measures were obtained among 524 of the children. Mixed models with random intercepts for children were used to account for correlation among repeated measures and to estimate child-specific exposures based on the “best linear unbiased predictor” (BLUP). Because the data were log normally distributed, log-transformed exposures were used in regression models and the geometric mean (GM) and geometric standard deviation (GSD) were used to summarize the distributions. Results: At baseline before intervention, the control and intervention arms had similar child CO distributions, 2.4 ± 2.4 ppm and 2.5 ± 1.8 ppm, respectively. In the control arm, there was a small reduction to 2.0 ± 2.2 ppm during the trial, which may be attributed to changing time–location patterns associated with age. However, a much more dramatic reduction in exposure to 1.0 ± 2.3 ppm was observed in the intervention arm. Adjusting for gender, age, season, and weekday, the mixed model estimated a 44% reduction (95% confidence interval: −48 to −39%) in child CO associated with the improved stove intervention. Younger age, female sex, and the rainy season were associated with slightly higher exposures. The intraclass correlation coefficient (ICC) was 0.28, indicating the limited reliability of a single measure as a surrogate for long-term exposure. Discussion: The plancha stove provided large reductions in child CO exposure. The low ICC indicates that most of the variability among the data is within subject rather than between subject. We will examine this issue in light of the repeated measures on each child and the observed predictors of exposure and consider the implications for child-specific predictions using the BLUP and attenuation of the hazard ratio for the effect of biomass smoke exposure on infant ALRI. “

INDOOR AIR POLLUTION FROM SOLID FUEL USE AND LOW BIRTH WEIGHT (LBW) IN PAKISTAN

ISEE-221 Introduction: The relationship between indoor fuel smoke and low birth weight (LBW) has not been well studied, although the associations of cigarette smoking, both active and passive, and outdoor air pollution with increased risk of LBW have been reported. Aim: The aim of this report is to identify the contribution of indoor air pollution from biomass fuel use to LBW in a population in Pakistan. Methods: Data were available for 941 pregnant women interviewed for a maternal health program in Pakistan. LBW defined as a birth weight (measured within 48 hours of birth) of < 2500 g, was 31%. To adjust for socio-economic confounding factors, a composite socio-economic status (SES) variable was created using, water supply, lighting source, toilet facilities, house ownership, construction, and density (occupants/room). Results: Mothers reporting use of wood as fuel had LBW of 38% compared to 22% in mothers using natural gas as fuel. A multiple logistic regression model showed that use of wood fuel, adjusted for SES, body mass index, serum Vitamin A levels, age, gravid status, and not receiving a tetanus toxoid injection in pregnancy, was independently associated with LBW. For pilot data air concentrations of carbon monoxide (CO) and particulate matter (PM2.5) were measured by electrochemical monitors (TSI, IAQ-CALCTM, Model 8762, and TSI Dust Track), in summer (n=14) and winter (n=12) stratified by fuel (wood and natural gas) and house construction (straw or bricks). Mean levels for 24 hours for CO were 24 ppm for wood use compared to 5 ppm in natural gas using kitchens with cooking time levels reaching above 150 ppm in wood-burning houses. Mean levels for PM 2.5 were 12 mg/ m3 in wood and 0.25 mg/m3in houses using natural gas. In wood using houses daytime average levels for PM 2.5 were from 2.2 to 30 mg/m3, and during cooking, they were as high as 300 mg/m3. The increased air concentrations of CO and PM 2.5 correlated well with each other and varied by an order of magnitude by the type of fuel used. Discussion: The findings of this study suggest an independent effect of indoor air pollution on birth weight, in line with findings from the few other studies available to date. Our analyses also suggest the importance of assessing LBW in populations where pregnant women are exposed to high levels of indoor air pollution from solid fuels.

Childhood asthma and indoor woodsmoke from cooking in Guatemala

We estimated the prevalence and severity of asthma, and the association with cooking on open wood fires, as preparation for a large-scale randomized field trial on effects of indoor air pollution and child health. This is one of the first systematic studies of asthma and indoor wood-smoke pollution and to our knowledge the first asthma study in a purely indigeneous population in Latin America. The mothers of 1058 children aged 4-6 years were interviewed, using the standardized ISAAC (International Study of Asthma and Allergies in Childhood) procedures and questionnaire. The study population is a Mam-speaking (Maya), indigenous group living at relatively high altitude (2000 m) in Western Guatemalan Highlands. We found that asthma prevalence is low among indigenous children in Guatemala, compared to other populations in Latin America. Only 3.3% of the children reported wheezing symptoms in the last 12 months, and 72% wheezing symptoms ever. The majority of the current wheezers had at least one of the criteria for severe asthma. The prevalence of all the symptoms of asthma was higher in children from households that used open fires compared to improved stoves with chimneys. In a logistic regression model, use of open fire for cooking was a significant risk factor for a number of asthma symptoms, with odds ratios varying from 2.0 to 3.5. Among the different cooking technologies (1-improved stove with chimney, 2-mixture of gas and open fire, 3-open fire) trends of higher prevalence with more pollution was found for some of the symptoms. Hence use of open fire for cooking, may be an important risk factor for asthma symptoms and severity.

Prevalence and risk factors of asthma and wheezing among US adults: an analysis of the NHANES III data.

The prevalence of asthma has been on the increase in the USA and worldwide. To understand the worsening epidemiological trends of asthma, this study analysed the data from the third National Health and Nutrition Examination Survey (NHANES III) to determine the prevalence and risk factors for asthma and wheezing among US adults. This analysis used data from 18,825 US adults aged > or = 20 yrs who had participated in the NHANES III project. After excluding subjects with physician-diagnosed emphysema, a total of 18,393 subjects were included in the final analysis. The prevalence of current asthma (asthma) was 4.5% and the prevalence of wheezing in the previous 12 months (wheezing) was 16.4%. Mexican-Americans exhibited the lowest prevalence of asthma when compared with other race/ethnic groups. Multiple logistic regression analysis showed that Mexican-Americans were less likely to report asthma when compared to non-Hispanic whites. Low education level, female sex, current and past smoking status, pet ownership, lifetime diagnosis of physician-diagnosed hay fever and obesity were all significantly associated with asthma and/or wheezing. No significant effect of indoor air pollutants, as derived from the use of household heating/cooking appliances, on asthma and wheezing was observed in this study. In conclusion, this study observed racial/ethnic differences in the prevalence of asthma and wheezing and identified several important risk factors that may contribute to development and/or exacerbation of asthma and wheezing. Contrary to earlier reports, the proxy measures of indoor air pollution used in this study were not found to be associated with increased risk of asthma and wheezing.

Indoor air pollution and respiratory health in the elderly.

People spend about > or = 80-90%, of their daily time indoors, elderly people especially at home. Thus, it is important to investigate possible health effects of indoor air pollutants and to consider their contributions to the total human exposure. This report summarises current knowledge on health effects of three common indoor air pollutants, respirable suspended particles, nitrogen dioxide and environmental tobacco smoke, with focus on the adults and the elderly. Preliminary findings on exposure distributions and health effects of these pollutants in older subjects of two panel studies carried out in Italian general populations will also be reported. The two indoor pollution studies were performed in the Po Delta area in North Italy (428 subjects and 140 houses investigated) and in Pisa in Central Italy (761 subjects and 282 houses investigated). Individuals aged > or = 65 yrs spent a significantly larger number of hours at home than the other age groups both in winter and in summer. A trend of higher occurrence of acute respiratory symptoms in the presence of environmental tobacco smoke was shown in comparison to the unexposed elderly both in winter (31 versus 29%) and summer (33 versus 16%). The occurrence of acute respiratory symptoms was consistently higher in relation to the high respirable suspended particles-index exposure compared to low exposure (33 versus 27%, in winter, 27 versus 21% in summer). Both the presence of environmental tobacco smoke at home and exposure to the high respirable suspended particles-index were associated with a decrease in the mean daily peak expiratory flow.

Indoor pollution and its impact on respiratory health

This overview discusses the respiratory complications of indoor air pollution, emphasizing the most common pollutants that individuals are likely to encounter outside the workplace. Data were obtained from a review of the recent literature. The expert opinion of the author was used to select and synthesize relevant data on this multifaceted subject. There have been a number of studies documenting an association between exposure to indoor allergens and development of both sensitization and asthma in children. In addition to classic allergens, chemical indoor air pollution may also exert an adverse effect on both the upper and lower respiratory tract by a variety of nonimmunologic, irritative mechanisms. Our understanding of the adverse effects of indoor air pollution on health and comfort has broadened in recent years. It has supplied a credible framework for developing and implementing a variety of control strategies.

Biomass energy in China and its potential

Biomass is a significant source of energy in China today, particularly in rural areas. However, most current use of firewood and agricultural residues for cooking and heating brings with it detrimental effects of indoor air pollution and associated adverse health impacts. In addition, the time spent collecting biomass fuels creates a burden on women and children, which reduces their time available for more productive activities. The availability of clean, low-cost fuels for heat and power in rural areas based on modern biomass technologies could significantly increase living standards and would be helpful in promoting rural industrialization and the generation of employment in rural areas. In addition, since sustainable use of biomass leads to no net increase in CO2 emissions, there would be global climate benefits arising from the widespread use of biomass. This article discusses the size of the biomass resource base in China, the current status of modernized biomass technology development, and near- and mid-term commercial targets for implementation of modern bioenergy systems in China. The article also describes some advanced biomass conversion systems that might play a role in China's energy system in the longer term. Finally, it describes current barriers and constraints on increasing the penetration of modernized biomass energy in China, along with some policy suggestions for addressing these.

Ventilation in homes and bronchial obstruction in young children.

We assessed the role of ventilation rate in homes in the development of bronchial obstruction during the first 2 years of life. We conducted a matched case-control study based on a cohort of 3,754 newborns in Oslo in 1992-93 that was followed for 2 years. The case series comprised 172 children with bronchial obstruction, and the control series was one-to-one matched for date of birth. Ventilation rate and other building characteristics were measured/collected in home visits, and questionnaires were used to obtain additional information. We found that the risk of bronchial obstruction was not directly associated with the ventilation rate in liters per second and per person (ventilation rate quartiles: 6.9, 11.5 and 17.6 l/s,p [liter/second and person]) in the homes (odds ratio; OR 0.98, 95% confidence interval (CI) 0.96-1.01). The odds ratios of bronchial obstruction were higher in the low air change group (air change rate < or =0.5 h(-1)) than in the high air change group owing to exposure to environmental tobacco smoke (low 1.8; 95% CI: 0.35-9.66; high 1.5; 95% CI: 0.74-3.20), dampness problems (low 9.6; 95% CI: 1.05-87.4; high 2.3; 95% CI: 0.83-6.39), and the presence of textile wall paper (low 3.7; 95% CI: 0.62-21.5; high 1.7; 95% CI 0.72-3.94) and plasticizer-containing surfaces (low 12.6; 95% CI: 1.00-159; high 2.6; 95% CI: 1.02-6.58). Our results are consistent with the hypothesis that low ventilation rates strengthen the effects of indoor air pollutants.

Indoor air pollution and the respiratory health of children

Children spend much of their time indoors, yet relatively little attention is paid to the effects of indoor air pollution owing to the difficulties of obtaining information about it. The most important single element is probably environmental tobacco smoke (passive smoking), which causes respiratory illness and impairment of lung function. Oxides of nitrogen, mostly derived from gas cookers, may cause symptoms in some children. House dust mites affect children with allergic asthma, but are very difficult to remove from the indoor environment. Indoor mould growth seems to be associated with ill-health, but it is not entirely clear whether this is attributable to exposure to the spores. Formaldehyde is emitted by some materials in buildings and furniture; it may affect children's respiratory health, but the information is rather sparse. VOCs are produced by a range of human activities; their significance for health is not known. More work is needed to ascertain the short-term and long-term effects of exposure to indoor air pollutants.

Health Effects of Indoor Air Pollutants and their Mitigation and Control

The nature of chemical, biological and physical contaminants present in indoor air, their sources, and the health effects they cause are reviewed. Among the physical agents, the interaction between tobacco smoke and radon is discussed. Control and improvement of indoor air quality can be achieved combining the use of two main strategies: proper design and construction of buildings, and control of indoor air pollution through source control, ventilation, air cleaning, exposure control, or a combination of them. A number of control measures primarily targeted to pollutants other than radon can also be particularly effective for radon. On the other hand, measures primarily targeted to radon containment can also be beneficial for other pollutants. Effective programmes on indoor air improvement are urgently needed to benefit the health, comfort and productivity of our communities.

Indoor biofuel air pollution and respiratory health: the role of confounding factors among women in highland Guatemala.

A number of studies have reported associations between indoor biofuel air pollution in developing countries and chronic obstructive lung disease (COLD) in adults and acute lower respiratory infection (ALRI) in children. Most of these studies have used indirect measures of exposure and generally dealt inadequately with confounding. More reliable, quantified information about this presumed effect is an important pre-requisite for prevention, not least because of the technical, economic and cultural barriers to achieving substantial exposure reductions in the world's poorest households, where ambient pollution levels are typically between ten and a hundred times higher than recommended standards. This study was carried out as part of a programme of research designed to inform the development of intervention studies capable of providing quantified estimates of health benefits. The association between respiratory symptoms and the use of open fires and chimney woodstoves ('planchas'), and the distribution of confounding factors, were examined in a cross-sectional study of 340 women aged 15-45 years, living in a poor rural area in the western highlands of Guatemala. The prevalence of reported cough and phlegm was significantly higher for three of six symptom measures among women using open fires. Although this finding is consistent with a number of other studies, none has systematically examined the extent to which strong associations with confounding variables in these settings limit the ability of observational studies to define the effect of indoor air pollution adequately. Very strong associations (P < 0.0001) were found between the type of fire and a number of household and socioeconomic factors including the arrangement of rooms, floor type, and possession of a radio and television. The spouse's economic activity type was also significantly associated (P < 0.05). Thus, while 82% of open fire users had dirt floors and only 18% cement or tile floors, the situation was reversed for plancha users, only 16% of whom had dirt floors. Confounding presents a substantial problem for observational studies of indoor air pollution and health, although there is a reasonable case for believing that the observed association is causal. Intervention studies are required for stronger evidence of this association, and more importantly, to determine the size of health benefit achievable through feasible exposure reductions.