Household air pollution from coal and biomass fuels in China: measurements, health impacts, and interventions

Seasonal variation of polycyclic aromatic hydrocarbons (PAHs) emissions in China

A regression model based on the provincial energy consumption data was developed to calculate the monthly proportions of residential energy consumption compared to the total year volume. This model was also validated by comparing with some survey and statistical data. With this model, a PAHs emission inventory with seasonal variation was developed. The seasonal variations of different sources in different regions of China and the spatial distribution of the major sources in different seasons were also achieved. The PAHs emissions were larger in the winter than in the summer, with a difference of about 1.3-folds between the months with the largest and the smallest emissions. Residential solid fuel combustion dominated the pattern of seasonal variation with the winter-time emissions as much as 1.6 times as that in the summer, while the emissions from wild fires and open fire straw burning was mainly concentrated during the spring and summer.

Seasonal and spatial occurrence and distribution of atmospheric polycyclic aromatic hydrocarbons (PAHs) in rural and urban areas of the North Chinese Plain

Passive air sampling (PAS) was employed to study the occurrence of gaseous and particle-bound PAHs in the North Chinese Plain. The averaged concentrations of gaseous and particle-bound PAHs were 485+/-209 ng/m(3) and 267+/-161 ng/m(3), respectively. The PAHs concentrations at urban sites were generally higher than those at rural ones with ratios <1.5 in spring, summer and fall, but differences between them were not significant for the wintertime and annually averaged concentrations. This urban-rural distribution pattern was related to the PAHs emission sources. PAHs spatial variation can be partially (49%) explained by emission with a simple linear regression method. Both the gaseous and particle-bound PAHs were highest in winter and lowest in summer, with winter/summer ratios of 1.8 and 8, respectively. Emission strength was the most important factor for the seasonality.

Strategies for addressing global environmental health concerns

While each region of the world faces unique public health challenges, environmental threats to vulnerable populations in Asia constitute a significant global public health challenge. Environmental threats to health are widespread and are increasing as nations in the region undergo rapid industrial development. One of the major predictors of ill health is poverty. Regional poverty puts large populations at risk for ill health, which exacerbates poverty and increases the exposure risk to environmental factors, such as pollution and disease. Patterns of illness have changed dramatically in the last century, and will continue to change in this century. Chemical toxicants in the environment, poverty, and little or no access to health care are all factors contributing to life-threatening diseases. Therefore, it is vital that we develop a better understanding of the mechanisms and interactions between nutrition, infectious disease, environmental exposures, and genetic predisposition in order to develop better prevention methods.

Variation in lung cancer risk by smoky coal subtype in Xuanwei, China

Lung cancer rates in Xuanwei County have been among the highest in China for both males and females and have been causally associated with exposure to indoor smoky (bituminous) coal emissions that contain very high levels of polycyclic aromatic hydrocarbons. There are numerous coal mines across the County. Although lung cancer risk is strongly associated with the use of smoky coal as a whole, variation in risk by smoky coal subtype has not been characterized as yet. We conducted a population-based case-control study of 498 lung cancer cases and 498 controls, individually matched to case subjects on age (+/-2 years) and sex to examine risk by coal subtype. Odds ratios (ORs) and 95% confidence intervals (CIs) for coal subtype were calculated by conditional logistic regression, adjusting for potential confounders. Overall, smoky coal use was positively and statistically significantly associated with lung cancer risk, when compared with the use of smokeless coal or wood (OR = 7.7, 95% CI = 4.5-13.3). Furthermore, there was a marked heterogeneity in risk estimates for specific subtypes of smoky coal (test for heterogeneity: p = 5.17 x 10(-10)). Estimates were highest for coal of the Laibin (OR = 24.8, 95% CI = 12.4-49.6) and Longtan (OR = 11.6, 95% CI = 5.0-27.2) coal types and lower for coal from other subtypes. These findings strongly suggest that in Xuanwei and elsewhere, the carcinogenic potential of coal combustion products can exhibit substantial local variation by specific coal source.

Effects of smoking and solid-fuel use on COPD, lung cancer, and tuberculosis in China: a time-based, multiple risk factor, modelling study

BACKGROUND

Chronic obstructive pulmonary disease (COPD), lung cancer, and tuberculosis are three leading causes of death in China, where prevalences of smoking and solid-fuel use are also high. We aimed to predict the effects of risk-factor trends on COPD, lung cancer, and tuberculosis.

METHODS

We used representative data sources to estimate past trends in smoking and household solid-fuel use and to construct a range of future scenarios. We obtained the aetiological effects of risk factors on diseases from meta-analyses of epidemiological studies and from large studies in China. We modelled future COPD and lung cancer mortality and tuberculosis incidence, taking into account the accumulation of hazardous effects of risk factors on COPD and lung cancer over time, and dependency of the risk of tuberculosis infection on the prevalence of disease. We quantified the sensitivity of our results to methods and data choices.

FINDINGS

If smoking and solid-fuel use remain at current levels between 2003 and 2033, 65 million deaths from COPD and 18 million deaths from lung cancer are predicted in China; 82% of COPD deaths and 75% of lung cancer deaths will be attributable to the combined effects of smoking and solid-fuel use. Complete gradual cessation of smoking and solid-fuel use by 2033 could avoid 26 million deaths from COPD and 6.3 million deaths from lung cancer; interventions of intermediate magnitude would reduce deaths by 6-31% (COPD) and 8-26% (lung cancer). Complete cessation of smoking and solid-fuel use by 2033 would reduce the projected annual tuberculosis incidence in 2033 by 14-52% if 80% DOTS coverage is sustained, 27-62% if 50% coverage is sustained, or 33-71% if 20% coverage is sustained.

INTERPRETATION

Reducing smoking and solid-fuel use can substantially lower predictions of COPD and lung cancer burden and would contribute to effective tuberculosis control in China.

Quality of indoor residential air and health

About 90% of our time is spent indoors where we are exposed to chemical and biological contaminants and possibly to carcinogens. These agents may influence the risk of developing nonspecific respiratory and neurologic symptoms, allergies, asthma and lung cancer. We review the sources, health effects and control strategies for several of these agents. There are conflicting data about indoor allergens. Early exposure may increase or may decrease the risk of future sensitization. Reports of indoor moulds or dampness or both are consistently associated with increased respiratory symptoms but causality has not been established. After cigarette smoking, exposure to environmental tobacco smoke and radon are the most common causes of lung cancer. Homeowners can improve the air quality in their homes, often with relatively simple measures, which should provide health benefits.

Indoor air pollution from biomass fuel smoke is a major health concern in the developing world

One-third of the world's population burn organic material such as wood, dung or charcoal (biomass fuel) for cooking, heating and lighting. This form of energy usage is associated with high levels of indoor air pollution and an increase in the incidence of respiratory infections, including pneumonia, tuberculosis and chronic obstructive pulmonary disease, low birthweight, cataracts, cardiovascular events and all-cause mortality both in adults and children. The mechanisms behind these associations are not fully understood. This review summarises the available information on biomass fuel use and health, highlighting the current gaps in knowledge.

Atmospheric transport and outflow of polycyclic aromatic hydrocarbons from China

A potential receptor influence function (PRIF) model, based on air mass forward trajectory calculations, was applied to simulate the atmospheric transport and outflow of polycyclic aromatic hydrocarbons (PAHs) emitted from China. With a 10 day atmospheric transport time, most neighboring countries and regions, as well as remote regions, were influenced by PAH emissions from China. Of the total annual PAH emission of 114 Gg, 92.7% remained within the boundary of mainland China. The geographic distribution of PRIFs within China was similar to the geographic distribution of the source regions, with high values in the North China Plain, Sichuan Basin, Shanxi, and Guizhou province. The Tarim basin and Sichuan basin had unfavorable meteorological conditions for PAH outflow. Of the PAH outflow from China (8092 tons or 7.1% of the total annual PAH emission), approximately 69.9% (5655 tons) reached no further than the offshore environment of mainland China and the South China Sea. Approximate 227, 71, 746, and 131 tons PAHs reached North Korea, South Korea, Russia-Mongolia region, and Japan, respectively, 2-4 days after the emission. Only 1.4 tons PAHs reached North America after more than 9 days. Interannual variation in the eastward PAH outflow was positively correlated to cold episodes of El Niño/Southern Oscillation. However, trans-Pacific atmospheric transport of PAHs from China was correlated to Pacific North America index (PNA) which is associated with the strength and position of westerly winds.

A comparison of particulate matter from biomass-burning rural and non-biomass-burning urban households in northeastern China

BACKGROUND

Biomass fuel is the primary source of domestic fuel in much of rural China. Previous studies have not characterized particle exposure through time-activity diaries or personal monitoring in mainland China.

OBJECTIVES

In this study we characterized indoor and personal particle exposure in six households in northeastern China (three urban, three rural) and explored differences by location, cooking status, activity, and fuel type. Rural homes used biomass. Urban homes used a combination of electricity and natural gas.

METHODS

Stationary monitors measured hourly indoor particulate matter (PM) with an aerodynamic diameter < or = 10 microm (PM10) for rural and urban kitchens, urban sitting rooms, and outdoors. Personal monitors for PM with an aerodynamic diameter < or = 2.5 microm (PM2.5) were employed for 10 participants. Time-activity patterns in 30-min intervals were recorded by researchers for each participant.

RESULTS

Stationary monitoring results indicate that rural kitchen PM10 levels are three times higher than those in urban kitchens during cooking. PM10 was 6.1 times higher during cooking periods than during noncooking periods for rural kitchens. Personal PM2.5 levels for rural cooks were 2.8-3.6 times higher than for all other participant categories. The highest PM2.5 exposures occurred during cooking periods for urban and rural cooks. However, rural cooks had 5.4 times higher PM2.5 levels during cooking than did urban cooks. Rural cooks spent 2.5 times more hours per day cooking than did their urban counterparts.

CONCLUSIONS

These findings indicate that biomass burning for cooking contributes substantially to indoor particulate levels and that this exposure is particularly elevated for cooks. Second-by-second personal PM2.5 exposures revealed differences in exposures by population group and strong temporal heterogeneity that would be obscured by aggregate metrics.

The non-occupational environment and the lung: opportunities for intervention

Many environmental factors, both indoors and outdoors, can cause or worsen respiratory disease. Although in many cases individuals have little influence over environmental exposures (e.g., weather conditions), there are many (such as environmental tobacco smoke (ETS) and outdoor air pollution) where interventions can improve health. While for environmental exposures such as air pollution, remediation largely devolves to the government, for exposures such as ETS advice to individuals in these settings will confer benefit. Climate change has begun to feature more and more in the context of health but how this may affect pulmonary disease remains debatable. It is possible that heat associated changes in allergen exposures may be more than counterbalanced by potential reductions in cold related exacerbations of diseases such as COPD. An improved assessment of environmental exposures is key in how we approach the effects of the environment on lung disease which would allow better understanding of gene-environment interactions and how remediation might influence population health for the better.

Lung cancer mortality is elevated in coal-mining areas of Appalachia

Previous research has documented increased lung cancer incidence and mortality in Appalachia. The current study tests whether residence in coal-mining areas of Appalachia is a contributing factor. We conducted a national county-level analysis to identify contributions of smoking rates, socioeconomic variables, coal-mining intensity and other variables to age-adjusted lung cancer mortality. Results demonstrate that lung cancer mortality for the years 2000-2004 is higher in areas of heavy Appalachian coal mining after adjustments for smoking, poverty, education, age, sex, race and other covariates. Higher mortality may be the result of exposure to environmental contaminates associated with the coal-mining industry, although smoking and poverty are also contributing factors. The knowledge of the geographic areas within Appalachia where lung cancer mortality is higher can be used to target programmatic and policy interventions. The set of socioeconomic and health inequalities characteristic of coal-mining areas of Appalachia highlights the need to develop more diverse, alternative local economies.

Neoplastic transformation of human small airway epithelial cells induced by arsenic

Human small airway epithelial cells (SAECs) previously immortalized with human telomerase reverse transcriptase (h-TERT) were continuously treated with sodium arsenite at a dose of 0.5 microg/mL in culture for up to 6 months. Arsenic-treated cells progressively displayed an increase in transformed phenotype including enhanced growth saturation density, plating efficiency, and anchorage-independent growth and invasion capability compared with their nontreated control cells. To determine whether arsenic-induced cell transformation was associated with genomic instability, treated and control cells were also analyzed for micronuclei formation. A 4.8-fold increase in micronuclei incidence in arsenic-treated cells was detected in conjunction with increased N-phosphonacetyl-l-aspartate (PALA)-resistant characteristics. In addition, arsenic-treated cells showed an increase in c-H-ras, c-myc, and c-fos protein expression relative to controls. The change in oncoprotein expression correlated with a decrease in wild-type p53 expression and hyperphosphorylated retinoblastoma. Taken together, these results strongly suggest that h-TERT immortalized human small airway epithelial cells underwent step-wise transformation after inorganic arsenic treatment.

Acrolein: sources, metabolism, and biomolecular interactions relevant to human health and disease

Acrolein (2-propenal) is ubiquitously present in (cooked) foods and in the environment. It is formed from carbohydrates, vegetable oils and animal fats, amino acids during heating of foods, and by combustion of petroleum fuels and biodiesel. Chemical reactions responsible for release of acrolein include heat-induced dehydration of glycerol, retro-aldol cleavage of dehydrated carbohydrates, lipid peroxidation of polyunsaturated fatty acids, and Strecker degradation of methionine and threonine. Smoking of tobacco products equals or exceeds the total human exposure to acrolein from all other sources. The main endogenous sources of acrolein are myeloperoxidase-mediated degradation of threonine and amine oxidase-mediated degradation of spermine and spermidine, which may constitute a significant source of acrolein in situations of oxidative stress and inflammation. Acrolein is metabolized by conjugation with glutathione and excreted in the urine as mercapturic acid metabolites. Acrolein forms Michael adducts with ascorbic acid in vitro, but the biological relevance of this reaction is not clear. The biological effects of acrolein are a consequence of its reactivity towards biological nucleophiles such as guanine in DNA and cysteine, lysine, histidine, and arginine residues in critical regions of nuclear factors, proteases, and other proteins. Acrolein adduction disrupts the function of these biomacromolecules which may result in mutations, altered gene transcription, and modulation of apoptosis.