Respiratory responses to diverse indoor combustion air pollution sources

Assessment and Impacts of Air Pollution from Brick Kilns on Public Health in Northern Pakistan

Brick kilns add enormous quantities of organic pollutants to the air that can cause serious health issues, especially in developing countries; poor air quality is associated with community health problems, yet receives no attention in Northern Pakistan. The present study, therefore, assessed the chemical composition and investigated the impacts of air pollution from brick kilns on public health. A field-based investigation of air pollutants, i.e., PM1, PM2.5 and PM10, CO2, CO, NO, NO2, H2S, and NH3 using mobile scientific instruments was conducted in selected study area locations. Social surveys were conducted to investigate the impacts of air pollution on community health. The results reveal the highest concentrations of PM1, PM2.5, and PM10, i.e., 3377, 2305, and 3567.67 µg/m3, respectively, in specific locations. Particulate matter concentrations in sampling points exceeded the permissible limits of the Pakistan National Environmental Quality Standard and, therefore, may risk the local population’s health. The highest mean value of CO2 was 529 mg/L, and other parameters, such as CO, NO, NO2, H2S, and NH3 were within the normal range. The social survey’s findings reveal that particulate matter was directly associated with respiratory diseases such as asthma, which was reported in all age groups selected for sampling. The study concluded by implementing air pollution reduction measures in brick kiln industries to protect the environment and community health. In addition, the region’s environmental protection agency needs to play an active role in proper checking and integrated management to improve air quality and protect the community from air hazards.

The impact of emissions from an essential oil diffuser on cognitive performance

Essential oil products are increasingly used in indoor environments and have been found to negatively contribute to indoor air quality. Moreover, the chemicals and fragrances emitted by those products may affect the central nervous system and cognitive function. This study uses a double-blind between-subject design to investigate the cognitive impact of exposure to the emissions from essential oil used in an ultrasonic diffuser. In a simulated office environment where other environmental parameters were maintained constant, 34 female and 25 male university students were randomly allocated into four essential oil exposure scenarios. The first two scenarios contrast lemon oil to pure deionized water, while the latter two focus on different levels of particulate matter differentiated by HEPA filters with non-scented grapeseed oil as the source. Cognitive function was assessed using a computer-based battery consisting of five objective tests that involve reasoning, response inhabitation, memory, risk-taking, and decision-making. Results show that exposure to essential oil emissions caused shortened reaction time at the cost of significantly worse response inhabitation control and memory sensitivity, indicating potentially more impulsive decision-making. The cognitive responses caused by scented lemon oil and non-scented grapeseed oil were similar, as was the perception of odor pleasantness and intensity.

The effects of indoor and outdoor air pollution on the prevalence of adults' respiratory diseases in four Chinese cities: a comparison between 2017-2018 and 1993-1996

Background

Over the past decades, both ambient and household air pollution have changed in several aspects, including the emission sources and the concentrations of pollutants, in many Chinese cities. It is unknown whether these changes are associated with changes in health conditions, especially given changes in other factors due to rapid economic growth.

Methods

Two cross-sectional surveys were conducted in two periods spanning more than twenty years (1993–1996 vs. 2017–2018) in four Chinese cities of Chongqing, Wuhan, Lanzhou, and Guangzhou. Data were collected regarding adults’ respiratory disease, smoking status, education, occupation, and household characteristics. Ambient air pollution data were obtained for each study. We first used logistic regression models to construct the district-specific adjusted disease prevalences. In the second stage, first-difference regression models were employed to examine whether the change in respiratory diseases prevalences was associated with the change in outdoor air pollution and indoor air pollution surrogates.

Results

A total of 7,557 and 9,974 households were participating in Period 1 (1993–1996) and Period 2 (2017–2018), respectively. Compared to Period 1, we found substantial reductions in the ambient air pollution concentrations, and a suggestive improvement in cooking-related indoor air pollution in Period 2. We observed decreases in the district-specific covariate-adjusted prevalences of both asthma and chronic bronchitis among participants, with an average reduction of 3.6% (range: 0.0% to 24.3%). From Period 1 to Period 2, one percent decrease in the proportion of cooking with coal was associated with a 19.0% (95% CI, 0.96–37.04%) decrease in the prevalence of males’ chronic bronchitis and a 1.86% (0.69–3.04%) increase in the prevalence of females’ asthma. Little evidence was observed regarding the potential health benefits associated with the decreases in ambient air pollution levels.

Conclusions

The substantial reduction in household use of coal for cooking might be an important contributor to the decrease in adults’ respiratory disease prevalence from 1993–1996 to 2017–2019 in four Chinese cities. Changes in this indoor air pollution source, along with other risk factors for respiratory diseases, may have masked respiratory health benefits associated with reductions in outdoor air pollution levels.

Air pollution and lung function in children

In this narrative review, we summarize the literature and provide updates on recent studies of air pollution exposures and child lung function and lung function growth. We include exposures to outdoor air pollutants that are monitored and regulated through air quality standards, and air pollutants that are not routinely monitored or directly regulated, including wildfires, indoor biomass and coal burning, gas and wood stove use, and volatile organic compounds. Included is a more systematic review of the recent literature on long-term air pollution and child lung function because this is an indicator of future adult respiratory health and exposure assessment tools have improved dramatically in recent years. We present "summary observations" and "knowledge gaps." We end by discussing what is known about what can be done at the individual/household, local/regional, and national levels to overcome structural impediments, reduce air pollution exposures, and improve child lung function. We found a large literature on adverse air pollution effects on children's lung function level and growth; however, many questions remain. Important areas needing further research include whether early-life effects are fixed or reversible; and what are windows of increased susceptibility, long-term effects of repeated wildfire events, and effects of air quality interventions.

Defining pediatric asthma: phenotypes to endotypes and beyond

Asthma is the most common chronic pediatric lung disease that has traditionally been defined as a syndrome of airway inflammation characterized by clinical symptoms of cough and wheeze. Highlighting the complex and heterogeneous nature of asthma, this review summarizes recent advances in asthma classification that are based on pathobiology, and thereby directly addresses limitations of existent definitions of asthma. By reviewing and contrasting clinical and mechanistic features of adult and childhood asthma, the review summarizes key biomarkers that distinguish childhood asthma subtypes. While atopy and its severity are important features of childhood asthma, there is evidence to support the existence of a childhood asthma endotype distinct from the atopic endotype. Although biomarkers of non-atopic asthma are an area of future research, we summarize a clinical approach that includes existing measures of airway-specific and systemic measures of atopy, co-existing morbidities, and disease severity and control, in the definition of childhood asthma, to empower health care providers to better characterize asthma disease burden in children. Identification of biomarkers of non-atopic asthma and the contribution of genetics and epigenetics to pediatric asthma burden remains a research need, which can potentially allow delivery of precision medicine to pediatric asthma. IMPACT: This review highlights asthma as a complex and heterogeneous disease and discusses recent advances in the understanding of the pathobiology of asthma to demonstrate the need for a more nuanced definitions of asthma. We review current knowledge of asthma phenotypes and endotypes and put forth an approach to endotyping asthma that may be useful for defining asthma for clinical care as well as for future research studies in the realm of personalized medicine for asthma.

Exposure to environmental tobacco smoke during pregnancy and infancy increased the risk of upper respiratory tract infections in infants: A birth cohort study in Wuhan, China

We aimed to evaluate the association of the exposure to environmental tobacco smoke (ETS) during pregnancy and infancy with the risk of upper respiratory tract infections (URTI) in infants based on a Chinese birth cohort study. Among 4178 infants who constituted the final study population, 46.8% experienced URTI in their first year of life. The hazard ratios (HR) and 95% confidence intervals (CI) for the risk of URTI were assessed using Cox regression models. Compared with no ETS during pregnancy, continued ETS during pregnancy was independently associated with a higher risk of URTI (HR: 1.36, 95% CI: 1.13, 1.63) after adjustment for potential confounders and also associated with earlier occurrence of URTI (log-rank P = .002). The association remained consistent across the strata defined according to maternal age, number of siblings, sex, and breastfeeding. Exposure to ETS during infancy was associated with URTI only among infants who were breastfed for less than 12 months (P for interaction < 0.05).Furthermore, infants exposed to ETS during both pregnancy and infancy showed the highest HR of 1.46 (95% CI: 1.16, 1.85) for URTI. Efforts should be made to protect pregnant women and infants from the adverse effects of indoor and outdoor ETS.

Asthma and allergic rhinitis among young parents in China in relation to outdoor air pollution, climate and home environment

We estimated associations between ambient air pollution, home environment and asthma as well as rhinitis among adults across China. A total of 40,279 young adults from eight Chinese cities participated in a questionnaire survey (participation rate 75%). There were questions on health and home environment. Information on city level gross domestic product (GDP) per capita, ambient temperature and PM₁₀ and NO₂ were collected from registers. Two-level logistic regression models were used to study health associations. Totally 1.6% reported asthma and 6.6% reported allergic rhinitis (AR). Higher temperature was associated with more asthma but less AR. Higher GDP was associated with less asthma but more AR. Higher degree of urbanization, higher level of NO₂ and living near heavily trafficked road were risk factors for asthma and AR. Participants in older buildings reported more asthma. Redecoration and buying new furniture were related to more asthma and AR (OR = 1.15-1.91). Using natural gas (OR = 1.34) and biomass (OR = 1.35) for cooking were risk factors for AR. Burning mosquito coils and incense increased the risk of asthma and AR. Cat keeping (OR = 2.88), dog keeping (OR = 2.04), cockroaches (OR = 1.54) and rats or mice (OR = 1.46) were associated with asthma. Cockroaches increased the risk of AR (OR = 1.22). Air humidifier and air cleaner were linked to asthma and AR. Frequent cleaning and exposing bedding to sunshine were protective. In conclusion, urbanization, NO₂ and traffic exhaust can increase the risk of adult asthma and AR. Higher ambient temperature was related to more asthma but less AR. Indoor animals such as cats, dogs, rats/mice and presence of cockroaches were associated with asthma or AR. Indoor chemical sources such as redecoration and new furniture were other risk factors. Cooking with natural gas or biomass and burning mosquito coils and incense were associated with asthma or AR. Frequent cleaning and exposing bedding to sunshine were protective.

Changes in children's respiratory morbidity and residential exposure factors over 25 years in Chongqing, China

Background

Respiratory morbidity and mortality during childhood remains a major challenge for global health. Due to the rapid economic development in Chongqing, we expect substantial temporal changes in respiratory health status and environmental risk factors in children. By leveraging a historical dataset, this study aims to assess the changes in prevalence of respiratory symptoms and diseases, residential exposure factors, and their associations in school-age children over a period of 25 years.

Methods

This study involved two cross-sectional surveys conducted in Chongqing with a 25-year interval (2017 vs. 1993). Purpose sampling was used to conduct questionnaire surveys on school-age children in both surveys. Information collected include children’s respiratory health outcomes, family residential exposures, demographic information, and parental respiratory disease history. The changes of residential exposures as well as demographics were determined by chi-square test. Odds ratios were calculated to compare the prevalence of children’s respiratory symptoms and diseases between the two periods. Associations between children’s respiratory outcomes and exposure indicators were assessed using multivariate logistic regressions.

Results

The majority of residential exposure indicators improved in 2017, including sleep in shared room, cooking with coal, poor kitchen ventilation, cooking frequency, and parental smoking. Compared to the 1993 study, the adjusted risk for children’s wheezing was lower (OR: 0.38, 95% CI: 0.29, 0.49), but the risk for bronchitis was higher (OR: 1.89, 95% CI: 1.54, 2.31) in the 2017 study. Poor kitchen ventilation and parental smoking were linked to an increased risk of children’s wheezing (OR: 1.39, 95% CI: 1.02, 1.90) and bronchitis (OR: 1.51, 95% CI: 1.02, 2.21), respectively, while heating in winter was linked to an increased risk of phlegm (OR: 1.40, 95% CI: 1.03, 1.90) and wheezing (OR: 1.47, 95% CI: 1.07, 2.01) in the 1993 study. However, these residential exposure factors were no longer associated with the children’s respiratory diseases in the 2017 study.

Conclusions

Our study found improvement of residential exposures in Chongqing, a decline of prevalence of children’s wheezing but an increase of that of bronchitis from 1993 to 2017. Poor kitchen ventilation, heating in winter, and parental smoking were significant risk factors in the 1993 survey but, with significantly reduced prevalence in 2017, were not significantly associated with children’s respiratory morbidity in the latter survey.

Lung Function of Children at Three Sites of Varying Ambient Air Pollution Levels in Uganda: A Cross Sectional Comparative Study

Air pollution is a major cause of sub-optimal lung function and lung diseases in childhood and adulthood. In this study we compared the lung function (measured by spirometry) of 537 Ugandan children, mean age 11.1 years in sites with high (Kampala and Jinja) and low (Buwenge) ambient air pollution levels, based on the concentrations of particulate matter smaller than 2.5 micrometres in diameter (PM_2.5). Factors associated with lung function were explored in a multiple linear regression model. PM_2.5 level in Kampala, Jinja and Buwenge were 177.5 µg/m³, 96.3 µg/m³ and 31.4 µg/m³ respectively (p = 0.0000). Respectively mean forced vital capacity as % of predicted (FVC%), forced expiratory volume in one second as % of predicted (FEV₁%) and forced expiratory flow 25⁻75% as % of predicted (FEF_25⁻75%) of children in high ambient air pollution sites (Kampala and Jinja) vs. those in the low ambient air pollution site (Buwenge subcounty) were: FVC% (101.4%, vs. 104.0%, p = 0.043), FEV₁% (93.9% vs. 98.0, p = 0.001) and FEF_25⁻75% (87.8 vs. 94.0, p = 0.002). The proportions of children whose %predicted parameters were less than 80% predicted (abnormal) were higher among children living in high ambient air pollution than those living in lower low ambient air pollutions areas with the exception of FVC%; high vs. low: FEV1 < 80%, %predicted (12.0% vs. 5.3%, p = 0.021) and FEF_25⁻75 < 80%, %predicted (37.7% vs. 29.3%, p = 0.052) Factors associated with lung function were (coefficient, p-value): FVC% urban residence (-3.87, p = 0.004), current cough (-2.65, p = 0.048), underweight (-6.62, p = 0.000), and overweight (11.15, p = 0.000); FEV₁% underweight (-6.54, p = 0.000) and FEF_25⁻75% urban residence (-8.67, p = 0.030) and exposure to biomass smoke (-7.48, p = 0.027). Children in study sites with high ambient air pollution had lower lung function than those in sites with low ambient air pollution. Urban residence, underweight, exposure to biomass smoke and cough were associated with lower lung function.

Indoor environmental factors associated with pulmonary function among adults in an acid rain-plagued city in Southwest China

OBJECTIVE

To assess the association of indoor environmental risk factors with respiratory function among adults in an acid rain-plagued city in China where coal use is frequent.

METHODS

The subjects were randomly selected in the winter season. Information on selected home environmental factors was collected through administered questionnaires. Additionally, pulmonary function tests, including Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 s (FEV₁), FEV₁/FVC and Peak Expiratory Flow Rate (PEFR) were also performed in participants.

RESULTS

This study showed that, among a variety of risk factors, coal fuel use, cooking oil fumes and active and passive smoking exposure together with asthma in childhood were important factors for deterioration of pulmonary function among adults in the winter season (p < 0.05). Additionally, subjects whose kitchen was located in the living room or bedroom, who opened their windows only occasionally or never, who noted the presence of cooking oil fumes and pests, whose bedroom was shared by 3 or more residents and who kept pets tended to exhibit lower values of FVC, FEV₁ and PEFR values compared with non-exposed counterparts (p < 0.05).

CONCLUSIONS

This study demonstrated impaired pulmonary function among adults who were exposed to indoor risk factors, such as coal fires and cigarette smoking compared to non-users in the winter season and emphasizes the need for public health efforts to decrease exposure to indoor air pollution.

Chronic cough: an Asian perspective. Part 1: Epidemiology

Asia is one of the most diverse and dynamic continents. Due to recent rapid industrialisation and urbanisation, morbidity patterns are likely to be diverse in Asian populations. Chronic cough is a disease condition resulting from host-environmental interactions, and is associated with a high global epidemiological burden. However, the underlying epidemiology remains unclear, particularly in Asia. We performed a literature search to identify peer-reviewed articles on chronic cough in community-based adult Asian populations that have been published between January 2000 and June 2015. In this review, we aim to examine the epidemiological characteristics and determinants of chronic cough in several geographical areas of Asia.

Relationship between pulmonary function and indoor air pollution from coal combustion among adult residents in an inner-city area of southwest China

Few studies evaluate the amount of particulate matter less than 2.5 mm in diameter (PM_2.5) in relation to a change in lung function among adults in a population. The aim of this study was to assess the association of coal as a domestic energy source to pulmonary function in an adult population in inner-city areas of Zunyi city in China where coal use is common. In a cross-sectional study of 104 households, pulmonary function measurements were assessed and compared in 110 coal users and 121 non-coal users (≥18 years old) who were all nonsmokers. Several sociodemographic factors were assessed by questionnaire, and ventilatory function measurements including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), the FEV₁/FVC ratio, and peak expiratory flow rate (PEFR) were compared between the 2 groups. The amount of PM_2.5 was also measured in all residences. There was a significant increase in the relative concentration of PM_2.5 in the indoor kitchens and living rooms of the coal-exposed group compared to the non-coal-exposed group. In multivariate analysis, current exposure to coal smoke was associated with a 31.7% decrease in FVC, a 42.0% decrease in FEV₁, a 7.46% decrease in the FEV₁/FVC ratio, and a 23.1% decrease in PEFR in adult residents. The slope of lung function decrease for Chinese adults is approximately a 2-L decrease in FVC, a 3-L decrease in FEV₁, and an 8 L/s decrease in PEFR per count per minute of PM_2.5 exposure. These results demonstrate the harmful effects of indoor air pollution from coal smoke on the lung function of adult residents and emphasize the need for public health efforts to decrease exposure to coal smoke.

Annual average ambient particulate matter exposure estimates, measured home particulate matter, and hair nicotine are associated with respiratory outcomes in adults with asthma

BACKGROUND

While exposure to outdoor particulate matter (PM) has been associated with poor asthma outcomes, few studies have investigated the combined effects of outdoor and indoor PM (including secondhand tobacco smoke).

OBJECTIVE

To examine the associations between PM and asthma outcomes.

METHODS

We analyzed data from a cohort of adults with asthma and rhinitis (n=302; 82% both conditions; 13% asthma only; 5% rhinitis alone) including measures of home PM, tobacco smoke exposure (hair nicotine and self-report), ambient PM from regional monitoring, distance to roadway, and season (wet or dry). The outcomes of interest were frequent respiratory symptoms and forced expiratory volume in 1 second (FEV1) below the lower limit of normal (NHANES reference values). Multivariable regression analyses examined the associations (Odds Ratio [OR] and 95% Confidence Interval [95%CI]) between exposures and these outcomes, adjusted by sociodemographic characteristics.

RESULTS

In adjusted analyses of each exposure, the highest tertile of home PM and season of interview were associated with increased odds for more frequent respiratory symptoms (OR=1.64 95%CI: [1.00, 2.69] and OR=1.66 95%CI: [1.09, 2.51]). The highest tertile of hair nicotine was significantly associated with FEV1 below the lower limit of normal (OR=1.80 95%CI: [1.00, 3.25]). In a model including home PM, ambient PM, hair nicotine, and season, only two associations remained strong: hair nicotine with FEV1 below the lower limit of normal and season of measurement (dry, April-October) with increased respiratory symptoms (OR=1.85 95%CI: [1.00, 3.41] and OR=1.54 95%CI: [1.0, 2.37]). When that model was stratified by sex, the highest tertiles of ambient PM and hair nicotine were associated with FEV1 below the lower limit of normal among women (OR=2.23 95%CI: [1.08, 4.61] and OR=2.90 95%CI: [1.32, 6.38]), but not men. The highest tertile of hair nicotine was also associated with increased respiratory symptoms in women but not men (OR=2.38 95%CI: [1.26, 4.49]). When stratified by age, the middle quartile of ambient PM and the highest hair nicotine tertile were associated with increased respiratory symptoms (OR=2.07 95%CI: [1.01, 4.24] and OR=2.55 95%CI: [1.21, 5.36]) in those under 55 but not in the older stratum.

CONCLUSIONS

Exposure to PM from both home and ambient sources is associated with increased symptoms and lower lung function in adults with asthma, although these associations vary by type of PM, the respiratory outcome studied, sex and age.

Urban vs. rural factors that affect adult asthma

In this review, our aim was to examine the influence of geographic variations on asthma prevalence and morbidity among adults, which is important for improving our understanding, identifying the burden, and for developing and implementing interventions aimed at reducing asthma morbidity. Asthma is a complex inflammatory disease of multifactorial origin, and is influenced by both environmental and genetic factors. The disparities in asthma prevalence and morbidity among the world's geographic locations are more likely to be associated with environmental exposures than genetic differences. In writing this article, we found that the indoor factors most consistently associated with asthma and asthma-related symptoms in adults included fuel combustion, mold growth, and environmental tobacco smoke in both urban and rural areas. Asthma and asthma-related symptoms occurred more frequently in urban than in rural areas, and that difference correlated with environmental risk exposures, SES, and healthcare access. Environmental risk factors to which urban adults were more frequently exposed than rural adults were dust mites,high levels of vehicle emissions, and a westernized lifestyle.Exposure to indoor biological contaminants in the urban environment is common.The main risk factors for developing asthma in urban areas are atopy and allergy to house dust mites, followed by allergens from animal dander. House dust mite exposure may potentially explain differences in diagnosis of asthma prevalence and morbidity among adults in urban vs. rural areas. In addition, the prevalence of asthma morbidity increases with urbanization. High levels of vehicle emissions,Western lifestyles and degree of urbanization itself, may affect outdoor and thereby indoor air quality. In urban areas, biomass fuels have been widely replaced by cleaner energy sources at home, such as gas and electricity, but in most developing countries, coal is still a major source of fuel for cooking and heating, particularly in winter. Moreover, exposure to ETS is common at home or at work in urban areas.There is evidence that asthma prevalence and morbidity is less common in rural than in urban areas. The possible reasons are that rural residents are exposed early in life to stables and to farm milk production, and such exposures are protective against developing asthma morbidity. Even so, asthma morbidity is disproportionately high among poor inner-city residents and in rural populations. A higher proportion of adult residents of nonmetropolitan areas were characterized as follows:aged 55 years or older, no previous college admission, low household income, no health insurance coverage, and could not see a doctor due to healthcare service availability, etc. In rural areas, biomass fuels meet more than 70% of the rural energy needs. Progress in adopting modern energy sources in rural areas has been slow. The most direct health impact comes from household energy use among the poor, who depend almost entirely on burning biomass fuels in simple cooking devices that are placed in inadequately ventilated spaces. Prospective studies are needed to assess the long-term effects of biomass smoke on lung health among adults in rural areas.Geographic differences in asthma susceptibility exist around the world. The reason for the differences in asthma prevalence in rural and urban areas may be due to the fact that populations have different lifestyles and cultures, as well as different environmental exposures and different genetic backgrounds. Identifying geographic disparities in asthma hospitalizations is critical to implementing prevention strategies,reducing morbidity, and improving healthcare financing for clinical asthma treatment. Although evidence shows that differences in the prevalence of asthma do exist between urban and rural dwellers in many parts of the world, including in developed countries, data are inadequate to evaluate the extent to which different pollutant exposures contribute to asthma morbidity and severity of asthma between urban and rural areas.

Atopic dermatitis and indoor use of energy sources in cooking and heating appliances

BACKGROUND

Atopic dermatitis (AD) prevalence has considerably increased worldwide in recent years. Studying indoor environments is particularly relevant, especially in industrialised countries where many people spend 80% of their time at home, particularly children. This study is aimed to identify the potential association between AD and the energy source (biomass, gas and electricity) used for cooking and domestic heating in a Spanish schoolchildren population.

METHODS

As part of the ISAAC (International Study of Asthma and Allergies in Childhood) phase III study, a cross-sectional population-based survey was conducted with 21,355 6-to-7-year-old children from 8 Spanish ISAAC centres. AD prevalence, environmental risk factors and the use of domestic heating/cooking devices were assessed using the validated ISAAC questionnaire. Crude and adjusted odds ratios (cOR, aOR) and 95% confidence intervals (CIs) were obtained. A logistic regression analysis was performed (Chi-square test, p-value < 0.05).

RESULTS

It was found that the use of biomass systems gave the highest cORs, but only electric cookers showed a significant cOR of 1.14 (95% CI: 1.01-1.27). When the geographical area and the mother's educational level were included in the logistic model, the obtained aOR values differed moderately from the initial cORs. Electric heating was the only type which obtained a significant aOR (1.13; 95% CI: 1.00-1.27). Finally, the model with all selected confounding variables (sex, BMI, number of siblings, mother's educational level, smoking habits of parents, truck traffic and geographical area), showed aOR values which were very similar to those obtained in the previous adjusted logistic analysis. None of the results was statistically significant, but the use of electric heating showed an aOR close to significance (1.14; 95% CI: 0.99-1.31).

CONCLUSION

In our study population, no statistically significant associations were found between the type of indoor energy sources used and the presence of AD.

OBSTRUCTIVE LUNG DISEASE AND EXPOSURE TO BURNING BIOMASS FUEL IN THE INDOOR ENVIRONMENT

It is estimated that up to half of the world's population burns biomass fuel (wood, crop residues, animal dung and coal) for indoor uses such as cooking, lighting and heating. As a result, a large proportion of women and children are exposed to high levels of household air pollution (HAP). The short and long term effects of these exposures on the respiratory health of this population are not clearly understood. On May 9-11, 2011 NIH held an international workshop on the "Health Burden of Indoor Air Pollution on Women and Children," in Arlington, VA. To gather information on the knowledge base on this topic and identify research gaps, ahead of the meeting we conducted a literature search using PubMed to identify publications that related to HAP, asthma, and chronic obstructive pulmonary disease (COPD). Abstracts were all analyzed and we report on those considered by the respiratory sub study group at the meeting to be most relevant to the field. Many of the studies published are symptom-based studies (as opposed to objective measures of lung function or clinical examination etc.) and measurement of HAP was not done. Many found some association between indoor exposures to biomass smoke as assessed by stove type (e.g., open fire vs. liquid propane gas) and respiratory symptoms such as wheeze and cough. Among the studies that examined objective measures (e.g. spirometry) as a health outcome, the data supporting an association between biomass smoke exposure and COPD in adult women are fairly robust, but the findings for asthma are mixed. If an association was observed between the exposures and lung function, most data seemed to demonstrate mild to moderate reductions in lung function, the pathophysiological mechanisms of which need to be investigated. In the end, the group identified a series of scientific gaps and opportunities for research that need to be addressed to better understand the respiratory effects of exposure to indoor burning of the different forms of biomass fuels.

Ambient particulate matter and lung function growth in Chinese children

BACKGROUND

Exposure to particulate matter (PM) has been associated with deficits in lung function growth among children in Western countries. However, few studies have explored this association in developing countries, where PM levels are often substantially higher.

METHODS

Children (n = 3273) 6-12 years of age were recruited from 8 schools in 4 Chinese cities. The lung function parameters of forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were measured using computerized spirometers twice a year for up to 3 years (1993-1996). Dichotomous samplers placed in each schoolyard were used to measure PM2.5 and PM10 (PM with diameter ≤ 2.5 μm and ≤ 10 μm, respectively). Multivariable generalized estimating equations were used to examine the association between the quarterly average PM levels and lung function growth during the period of follow-up.

RESULTS

Annual average PM2.5 and PM10 levels in the 4 cities ranged from 57 to 158 μg/m and 95 to 268 μg/m, respectively. In multivariable models, an increase of 10 μg/m of PM2.5 was associated with decreases of 2.7 mL FEV1 (95% confidence interval = -3.5 to -2.0), 3.5 mL FVC (-4.3 to -2.7), 1.4 mL/year FEV1 growth (-1.8 to -0.9), and 1.5 mL/year FVC growth (-2.0 to -1.0). Similar results were seen with PM10 exposure.

CONCLUSIONS

Exposure to ambient particulate matter was associated with decreased growth in lung function among Chinese children.

Roles of pollution in the prevalence and exacerbations of allergic diseases in Asia

The prevalence of asthma and allergic diseases has been found to be increasingly rapidly, especially in developing countries. Environmental factors have been found to be important contributors to the manifestations of allergic diseases. Air pollution has been extensively studied in different regions of the world. The levels of ambient air pollutants in many Asian countries are very high when compared with those in developed Western countries. However, the prevalence of asthma was relatively low across many Asian countries. Many studies have clearly documented that environmental air pollution is an important factor resulting in exacerbations of asthma. In particular, levels of traffic-related pollutants are increasing rapidly across many Asian countries in parallel with the level of urbanization and economic development. The loss of protective factors associated with a rural environment will further contribute to the adverse effect on patients with allergic diseases such as asthma. In this review the roles of air pollution were examined in relation to the inception and exacerbations of allergic diseases in Asia.

Estimating the health effects of exposure to multi-pollutant mixture

PURPOSE

Air pollution constitutes a major public health concern because of its ubiquity and of its potential health impact. Because individuals are exposed to many air pollutants at once that are highly correlated with each other, there is a need to consider the multi-pollutant exposure phenomenon. The characteristics of multiple pollutants that make statistical analysis of health-related effects of air pollution complex include the high correlation between pollutants prevents the use of standard statistical methods, the potential existence of interaction between pollutants, the common measurement errors, the importance of the number of pollutants to consider, and the potential nonlinear relationship between exposure and health.

METHODS

We made a review of statistical methods either used in the literature to study the effect of multiple pollutants or identified as potentially applicable to this problem. We reported the results of investigations that applied such methods.

RESULTS

Eighteen publications have investigated the multi-pollutant effects, 5 on indoor pollution, 10 on outdoor pollution, and 3 on statistical methodology with application on outdoor pollution. Some other publications have only addressed statistical methodology.

CONCLUSIONS

The use of Hierarchical Bayesian approach, dimension reduction methods, clustering, recursive partitioning, and logic regression are some potential methods described. Methods that provide figures for risk assessments should be put forward in public health decisions.

Indoor air pollution and lung function growth among children in four Chinese cities

Ambient air pollution has been associated with decreased growth in lung function among children; but little is known about the impact of indoor air pollution. We examined relationships between indoor air pollution metrics and lung function growth, among children (n = 3273) aged 6-13 years living in four Chinese cities. Lung function parameters (FVC and FEV(1) ) were measured twice a year. Questionnaires were used to determine home coal burning and ventilation practices. Generalized estimating equations were used to examine associations. Use of coal as a household fuel was associated with 16.5 ml/year lower (33%, P < 0.001) and 20.5 ml/year lower (39%, P < 0.001) growth in children's FEV(1) and FVC, respectively. FEV(1) growth was 10.2 ml/year higher (20%, P = 0.009), and FVC growth was 17.0 ml/year higher (33%, P < 0.001) among children who lived in houses with the presence of a ventilation device. Among children living in houses where coal was used as a fuel and no ventilation devices were present, adjusted FVC and FEV(1) growth, respectively, were 37% and 61% that of the average growth per year in the full cohort. This suggests that household coal use may cause deficits in lung function growth, while using ventilation devices may be protective of lung development.

PRACTICAL IMPLICATIONS

Nearly 3.4 billion people use solid fuels in homes for cooking and/or heating. We report the following findings from a longitudinal study: (i) household coal use is significantly associated with reduction in children's lung function growth and (ii) the use of household ventilation devices is significantly associated with higher lung function growth, particularly among children living in households where coal is used as a fuel. These findings not only provide evidence that indoor coal use impairs children's lung development but also point to the importance of improving ventilation conditions in reducing harmful effects of indoor air pollution sources.

Impaired lung function in individuals chronically exposed to biomass combustion

BACKGROUND

The use of biomass for cooking and heating is considered an important factor associated with respiratory diseases. However, few studies evaluate the amount of particulate matter less than 2.5 μm in diameter (PM2.5), symptoms and lung function in the same population.

OBJECTIVES

To evaluate the respiratory effects of biomass combustion and compare the results with those of individuals from the same community in Brazil using liquefied petroleum gas (Gas).

METHODS

1402 individuals in 260 residences were divided into three groups according to exposure (Gas, Indoor-Biomass, Outside-Biomass). Respiratory symptoms were assessed using questionnaires. Reflectance of paper filters was used to assess particulate matter exposure. In 48 residences the amount of PM2.5 was also quantified. Pulmonary function tests were performed in 120 individuals.

RESULTS

Reflectance index correlated directly with PM2.5 (r=0.92) and was used to estimate exposure (ePM2.5). There was a significant increase in ePM2.5 in Indoor-Biomass and Outside-Biomass, compared to Gas. There was a significantly increased odds ratio (OR) for cough, wheezing and dyspnea in adults exposed to Indoor-Biomass (OR=2.93, 2.33, 2.59, respectively) and Outside-Biomass (OR=1.78, 1.78, 1.80, respectively) compared to Gas. Pulmonary function tests revealed both Non-Smoker-Biomass and Smoker-Gas individuals to have decreased %predicted-forced expiratory volume in the first second (FEV1) and FEV1/forced vital capacity (FVC) as compared to Non-Smoker-Gas. Pulmonary function tests data was inversely correlated with duration and ePM2.5. The prevalence of airway obstruction was 20% in both Non-Smoker-Biomass and Smoker-Gas subjects.

CONCLUSION

Chronic exposure to biomass combustion is associated with increased prevalence of respiratory symptoms, reduced lung function and development of chronic obstructive pulmonary disease. These effects are associated with the duration and magnitude of exposure and are exacerbated by tobacco smoke.

Do indoor environments influence asthma and asthma-related symptoms among adults in homes?: a review of the literature

This review summarizes the results of epidemiological studies focusing on the detrimental effects of home environmental factors on asthma morbidity in adults. We reviewed the literature on indoor air quality (IAQ), physical and sociodemographic factors, and asthma morbidity in homes, and identified commonly reported asthma, allergic, and respiratory symptoms involving the home environment. Reported IAQ and asthma morbidity data strongly indicated positive associations between indoor air pollution and adverse health effects in most studies. Indoor factors most consistently associated with asthma and asthma-related symptoms in adults included fuel combustion, mold growth, and environmental tobacco smoke. Environmental exposure may increase an adult's risk of developing asthma and also may increase the risk of asthma exacerbations. Evaluation of present IAQ levels, exposure characteristics, and the role of exposure to these factors in relation to asthma morbidity is important for improving our understanding, identifying the burden, and for developing and implementing interventions aimed at reducing asthma morbidity.

Quantitative assessments of indoor air pollution and respiratory health in a population-based sample of French dwellings

BACKGROUND

Various volatile organic compounds (VOCs) have been related to respiratory health effects, but have generally been assessed individually without taking into account the fact that such pollutants are highly correlated to one other.

AIMS

We investigated the effects of exposure to various VOC, and considered their combined effect on adult asthma and rhinitis.

METHOD

A national cross-sectional representative survey conducted by the Indoor Air Quality Observatory objectively assessed 20 VOCs in 490 main dwellings in France. A standardized questionnaire determined the prevalence of asthma and rhinitis among 1012 inhabitants of the dwellings (≥ 15 years). Marginal models for binary outcome were used to relate VOCs exposure to asthma and rhinitis, controlling for potential confounders. A global score representing the number of VOCs in each dwelling with an elevated concentration (using the 3(rd) quartile value of the distribution as a threshold value) was then derived as a measure of the combined effect of VOCs. Specific scores were built using a similar approach, grouping VOCs by family.

RESULTS

Asthma (8.6%) was significantly associated with N-undecane and 1,2,4-trimethylbenzene and rhinitis (38.3%) with ethylbenzene, trichloroethylene, m/p- and o-xylene. The global VOC score was associated with a significant risk of asthma and rhinitis (odds ratio (OR) of 1.40 and 1.22, respectively, for 5 additional VOCs with high exposure level). Both specific scores for aromatic hydrocarbons and aliphatic hydrocarbons were associated with a significantly risk of asthma (OR=1.12; 95% confidence interval (CI): 1.01-1.24 and OR=1.41; 95% CI=1.03-1.93, respectively). The specific VOC score for halogenated hydrocarbons was associated with a significant risk of rhinitis (OR=1.28; 95% CI: 1.07-1.54).

CONCLUSION

We have shown that high concentrations of VOCs in homes were associated with an increasing prevalence of asthma and rhinitis in adults.

Indoor air pollution from unprocessed solid fuels in developing countries

Approximately half of the world's population relies on biomass (primarily wood and agricultural residues) or coal fuels (collectively termed solid fuels) for heating, lighting, and cooking. The incomplete combustion of such materials releases byproducts with well-known adverse health effects, hence increasing the risk of many diseases and death. Among these conditions are acute respiratory infections, chronic obstructive pulmonary disease, heart disease, stroke, lung cancer, cataracts and blindness, tuberculosis, asthma, and adverse pregnancy outcomes. The International Agency for Research on Cancer has classified the indoor combustion of coal emissions as Group 1, a known carcinogen to humans. Indoor air pollution exposure is greatest in individuals who live in rural developing countries. Interventions have been limited and show only mixed results. To reduce the morbidity and mortality from indoor air pollution, countermeasures have to be developed that are practical, efficient, sustainable, and economical with involvement from the government, the commercial sector, and individuals. This review focuses on the contribution of solid fuels to indoor air pollution.

Indoor exposure to environmental cigarette smoke, but not other inhaled particulates associates with respiratory symptoms and diminished lung function in adults

BACKGROUND AND OBJECTIVE

Exposure to particulate matter (PM) can induce airway inflammation and exacerbation of asthma. However, there is limited knowledge about the effects of exposure to indoor sources of PM. We investigated the associations between self-reported exposure to indoor sources of PM and lower airway symptoms and lung function.

METHODS

A population-based cross-sectional study of 3471 persons aged 18-69 years was conducted. Information about exposure to indoor sources of PM and airway symptoms was obtained from a self-administered questionnaire.

RESULTS

Exposure to wood stoves, candles and gas cookers was not significantly associated with an increased prevalence of lower respiratory symptoms or decreased lung function. In contrast, persons exposed to environmental tobacco smoke for >5 h/day had a significantly increased risk of 'wheeze' (OR 1.69, 95% CI: 1.24-2.30) and 'chronic cough' (OR 1.57, 95% CI: 1.12-2.20), as well as decreased lung function (FEV(1)% predicted), compared with those who were not exposed. Similar trends were observed in never smokers.

CONCLUSIONS

In this cross-sectional study of an adult general population, self-reported exposure to environmental tobacco smoke, but not self-reported exposure to wood stoves, candles or gas cookers, appeared to be associated with an increased prevalence of lower airway symptoms and decreased lung function.

Asthmatic symptoms among pupils in relation to winter indoor and outdoor air pollution in schools in Taiyuan, China

BACKGROUND

There are few studies on associations between children's respiratory heath and air pollution in schools in China. The industrial development and increased traffic may affect the indoor exposure to air pollutants in school environment. Moreover, there is a need to study respiratory effects of environmental tobacco smoke (ETS) and emissions from new building materials in homes in China.

OBJECTIVES

We studied the associations between pupils' asthmatic symptoms and indoor and outdoor air pollution in schools, as well as selected home exposures, in a coal-burning city in north China.

METHODS

A questionnaire survey was administered to pupils (11-15 years of age) in 10 schools in urban Taiyuan, collecting data on respiratory health and selected home environmental factors. Indoor and outdoor school air pollutants and climate factors were measured in winter.

RESULTS

A total of 1,993 pupils (90.2%) participated; 1.8% had cumulative asthma, 8.4% wheezing, 29.8% had daytime attacks of breathlessness. The indoor average concentrations of sulfur dioxide, nitrogen dioxide, ozone, and formaldehyde by class were 264.8, 39.4, 10.1, and 2.3 microg/m3, respectively. Outdoor levels were two to three times higher. Controlling for possible confounders, either wheeze or daytime or nocturnal attacks of breathlessness were positively associated with SO2, NO2, or formaldehyde. In addition, ETS and new furniture at home were risk factors for wheeze, daytime breathlessness, and respiratory infections.

CONCLUSIONS

Indoor chemical air pollutants of mainly outdoor origin could be risk factors for pupils' respiratory symptoms at school, and home exposure to ETS and chemical emissions from new furniture could affect pupils' respiratory health.