Effects of biomass burning on human health

Research studies on wood smoke and other air pollution.

Effects of biomass burning on human health

Postby Wilberforce » Thu Apr 17, 2014 6:46 pm

English full text
Effects of biomass burning on human health
José Eduardo Delfini Cançado
http://www.scielo.br/scielo.php?pid=S18 ... xt&tlng=en

Air pollution is a widely discussed topic in the world. The first idea that comes to mind of people and the researcher is to link air pollution to large urban centers, with the image of pollutants being eliminated by motor vehicles or the chimney of their factories. However, a considerable portion of the world population lives with another source of pollution, which primarily affects developing countries: the burning of biomass. This paper describes the main conditions that lead to the burning of biomass, as the literature has recorded its effects on human health, discussing its effects on respiratory morbidity of the population exposed.


Since the beginning of the last century, studies in the medical literature have documented a significant association between air pollution resulting from the emission of fossil fuels and increased morbidity and mortality in humans in developed countries.
These effects were even to levels of airborne pollutants considered safe for the health of the population exposta1 observed. However, few studies have been conducted to evaluate the effects produced by burning biomass (any material of plant or animal origin used as an energy source). In 1985, a bulletin of the World Health Organization (WHO) wondered what would be the severity and extent of damage caused by air pollution as a result of biomass combustion in rural areas of countries in development2.

The incineration of biomass is the largest domestic source of energy in countries development3. Approximately half the world's population, and over 90% of homes in the countryside of developing countries, remain using energy from the burning of biomass in the form of wood, charcoal, animal dung and agricultural residues, which produces high levels of air pollution indoors, where they remain women cooking and children.

Despite the great technological advances experienced by humanity, deliberate or accidental burning of vegetation becomes sometimes uncontrolled, reaching large tracts of forests, savannas, or other less dense vegetation. Fire is a growing problem in that remaining tropical forests in the world and pollution due to smoke generated has an important impact on the health of exposed populations. This impact includes increased mortality, hospital admissions, emergency room visits and the use of drugs, due to respiratory and cardiovascular diseases, and decreased function pulmonar4.

Despite years of scientific studies and media attention in relation to deforestation and forest fires, the incidence and effect of forest fires have been ignored. Large fires in Borneo (1983 and 1997), Thailand (1997), Indonesia (1997), Roraima (1997-1998), Mato Grosso (1998) and Pará (1998) called the attention to the problem, but the measures taken to prevent or control such fires are still insuficientes5.

The combustion process

Combustion is a chemical process by which a material reacts rapidly with oxygen in the air causing light and intense heat. About 80% of the biomass combustion occurs in the tropics. It is a major source of production of particulate matter and greenhouse gases on the planet, influences the chemistry and atmospheric physics, chemical species that produces significantly change the pH of rainwater and affects the heat balance of the atmosphere by interfering with the amount of radiation solar reflected to the espaço6.

Biomass burning in indoor environments and health problems

Soot found in caves in southern Africa indicate that the human race uses fire 1.5 million years ago.

Air pollution indoors existed since prehistoric times, when humans began their movement to areas with temperate climate, some 200 thousand years ago.

The health effects arising from exposure over long periods to the smoke produced by burning biomass indoors, have been associated with chronic pulmonale obstructive pulmonary disease (COPD) and color crônico7, 8, bronquiectasia9, 10, pneumoconiose11, and black lung fibrosis pulmonary difusa12 13.

This and other evidence led to the inclusion of pollution indoors by combustion of biomass in relation to risk factors for the development of COPD presented at The Global Strategy for Diagnosis, Management, and Prevention of Chronic Obstructive Lung Disease (GOLD).

Air pollution indoors existed since prehistoric times, when humans began their movement to areas with temperate climate, some 200 thousand years ago.

Acute respiratory infection of the lower airways (IRVI) is the most important cause of mortality in children under five years, causing approximately 2 million deaths annually. Sixteen epidemiological studies, 11 case-control and five cohort, during the last 20 years in developing countries, have shown an association between exposure to pollution from biomass burning indoors and acute respiratory infections in crianças14.

Study in Guatemala showed that the weight of newborns from households that used biomass as fuel was 63 g (95% CI: 0.4 to 127, p = 0.049) lower compared to newborns from households that used fuel "clean" (15).

Case-control study in schoolchildren in Kenya showed an increase in the number of asthmatics in homes that had smoke exposure madeira18. Another study in Nepal, using the ISAAC (International Study of Asthma and Allergies in Children) assessed adolescents from eleven to seventeen and found an OR of 1.81 (1.04 - 4.8) for asthma compared to those using biomass as an energy source and those using gas or querosene16.

Recent studies have also suggested an association between biomass burning in internal and Tuberculosis pulmonar17 18 environments. The environmental exposure to particulate matter can be a booster of the binomial misery / TB, so far, only explained by malnutrition, overcrowding and inadequate access to health services.

In India, the analysis of approximately 170 000 individuals showed an OR of 1.32 (95% CI 1.16 to 1.50) for complete or partial blindness, comparing patients who preferentially used biomass and other types of fuel, after analyzing socioeconomic status, and living conditions, and variables geográficas19, 20.

All these effects have been well documented in developing countries, where women and their children remain several hours cooking on stoves whose fuel is biomass in areas without adequate ventilation.

Biomass burning in fields and health problems

The smoke from burning biomass in open environments produce indirect adverse health effects, such as reduced photosynthesis, which causes loss of crops, or blocking of ultraviolet A and B, which causes an increase of pathogenic microorganisms air and water, and increased larval mosquitoes of doenças21.

In 1997, as a result of El Niño, uncontrollable forest fires in Southeast Asia, resulting in high air pollution in the region occurred, affecting a population of 300 million people and causing a health expenditure of 4.5 billion dollars . This caught the attention of health authorities around the mundo22.

Recent studies have also suggested an association between biomass burning in internal and pulmonary tuberculosis environments.

The environmental exposure to particulate matter can be a booster of the binomial misery / TB, so far, only explained by malnutrition, overcrowding and inadequate access to health services.

In Indonesia there was an increase in attendances for asthma, chronic bronchitis and acute respiratory infection. Respiratory pathologies motivated 36,462 emergency room visits, 15,822 hospitalizations, and 2,446,352 days of work perdidos23.

In Malaysia there was an increase of asthma attacks in children and lung function in schoolchildren decreased during the period agudo24.

The Ministry of Health of Singapore reported a 30% increase in outpatient visits related to respiratory pathologies. An increase in the levels of PM10 of 50 mg/m3 to 150 mg/m3 was significantly associated to an increase of 13%, 19% and 26% of acute respiratory infections, asthma and rhinitis, respectively (25).

In Central Kalimantan, Borneo, one of the areas most affected by fog, the number of hospitalized patients with pneumonia was 33 times higher than in the previous twelve months. In Sumatra there was an increase of hospitalizations for bronchitis, acute laryngitis and bronchiectasis, 1.6, 8.0 and 3.9 times, respectively, compared to the average histórica26.

Tan et al.27 evaluated the leukocyte count in 30 volunteers (military) without disease using peripheral blood samples, and compared the period of time after the fog with mist. The result showed that during the greater air pollution there was a significant increase in the number of leukocytes due to an increase of polymorphonuclears. The authors suggest that air pollution caused by burning biomass is associated with an increase in white blood cells due to a greater release of precursors of polymorphonuclear cells by the bone marrow, and that this response may contribute to the pathogenesis of cardiopulmonary morbidity associated with acute episodes of air pollution. Eeden et al.28 using the same group of individuals, demonstrated that there was an increase in circulating cytokines.

In 1987 a major fire in California (USA) increased levels of TSP and PM10 values ​​up to 1000 and 237 mg/m3, respectively. This fact has caused an increase in emergency room visits for asthma, COPD, laryngitis, sinusitis and other respiratory infections in the order of 40%, 30%, 60%, 30% and 50%, respectively29.

Individuals with chronic respiratory disorders were more susceptible to the effects of pollution generated by burning vegetation. During forest fires in 1994 in Singapore, was an increase of 20% in seeking care in emergency rooms for asthmatic children compared to the average anuais30. Compared to adults, the smoke from the burning of straw and agricultural residues produced in individuals with severe obstruction of the airways with moderate intensity, exacerbation of symptoms, such as dyspnea, respiratory distress, coughing and sibilos31.

Burning of cane sugar and health problems in Brazil

All studies related to vegetation burning in the open air concern random episodes. There is, however, a region of the world where biomass burning is done programmatically. In the 1970s, during the oil crisis, the Brazilian government implemented a program called Proálcool with the goal of producing an alternative, renewable and non-polluting fuel: ethanol derived from sugar cane. This program culminated in a large production of alcohol-fueled from the 80 vehicles, and a large increase of the culture of cane sugar in the country, especially in the state of São Paulo, the largest producer. But there is a counterpoint: the cane sugar is a natural crop, since, for reasons of productivity and safety, harvesting is carried out after the burning of fields. Particulate matter and gases generate a smog similar to large urban centers most polluted in the world, changing the characteristics of the regions where sugar cane is grown, harvested and industrialized.

The authors suggest that air pollution caused by burning biomass is associated with an increase in white blood cells due to a greater release of precursors of polymorphonuclear cells by the bone marrow, and that this response may contribute to the pathogenesis of cardiopulmonary morbidity associated with acute episodes of air pollution.

From a medical standpoint, interest in the problem lies in the fact that many patients with chronic respiratory diseases, especially sinusitis, chronic bronchitis, emphysema and asthma related worsening of their symptoms in the year that coincides with the fires. But not only. Healthy individuals, the same time of year, refer often irritation in the upper airways and eyes.

Franco (32), in 1992, made some considerations about the relationship between the burning of cane sugar and health problems:

1. The Burning sugarcane is not the only factor of worsening air quality, but in consequence of the extension of acreage and duration of fires, from April to November, discharges of gases and other pollutants in the atmosphere of the region gain an important meaning;
. 2 The exposed population, which has decreased quality of life and health aggravated by adverse weather conditions, is quite significant;
3. Exposed population requires a much larger number of visits, outpatient visits, medications, and hospitalizations. This is levied not only medical services, but the economy of families.

Study aimed to evaluate the association between particulate matter collected during the burning of plantations of sugar cane and an indicator of respiratory morbidity in Araraquara (SP), found a significant and dose-dependent positive association between the daily number inhalations and particulate. An increase of 10 mg in the particulate was associated with a relative risk of inhalation therapy of 1.09 (95% CI: 1.01 to 1.18). In the most polluted days, the relative risk of inhalation therapy was 1.20 (1.03 to 1.39). These results indicate that the burning of plantations of cane sugar causes deleterious health effects of exposta33 population.

Study conducted in the city of Piracicaba (SP) correlated the increase in particulate matter and daily hospital admissions for respiratory diseases in children, adolescents (under 13 years old) and elderly (over 65 years). The principal components analysis identified that the absolute biomass burning and re-suspension of eroded soil material are responsible for 80% of the fine particulate matter (PM2, 5) in the region. The relative risk of hospitalization for respiratory disease was significantly associated with variation of particulate. An increase of 10.2 mg/m3 in PM2, 5 is associated with an increase of 21.4% (95% CI 4.3, 38.5) in hospitalizations for respiratory diseases in children and adolescents. When comparing the periods of burning and non burning of cane sugar, the effect was 3.5 times higher during firing, which shows the impact of this type of air pollution on the health of the population exposta34.


The physical and biological changes in the environment due to human activity resulted in a huge impact on health. The extent of these changes, which resonates today, and still compromises the future, is not fully established. For example, past emissions of carbon monoxide and other gases causing the greenhouse effect and depletion of the ozone layer in the stratosphere, are still current problems that face us. Likewise, the continuous modification of the ecological systems that sustain human life in the future may represent a threat to health globally. Because the effects of greenhouse gases, the surface temperature increased by about 1.2 ° C since 1850, with 0.5 ° C between 1978 and the present day, leading to a continued warming of the sea surface, which causes changes of direction in the deep ocean currents with dramatic regional climate changes, causing problems such as water shortages and food.

Among the reasons for the continued development of the human species is the protection of health. However, there is a slowdown in the evaluation and implementation of remedial measures when it comes to the environment and health relationship, especially when it comes to burning biomass.

Estimates show that in 2000, 351 million hectares of vegetation on the planet were affected by the fire. The population affected by the products generated by the combustion of biomass, as a rule, corresponds to individuals with higher levels of poverty, with less possibility of access to health services, which certainly does worsen their already precarious quality of life.

The effects found in studies with biomass burning are similar to those observed in studies of air pollution produced by burning fossil fuels reinforces the hypothesis that the deleterious effect of air pollution on human health is similar, regardless of its source .

In Brazil, especially in São Paulo, the problem of pollution caused by the burning of cane sugar is very serious because of the large extent of the acreage (approximately 6 million hectares) and difficult to solve, since that this culture has a huge economic importance for many regions and the country itself. Therefore, although the alcohol is an excellent renewable fuel, burning cane fields in the pre-harvest is an archaic method and effective measures to ban this activity should be implemented in the short term by the competent authorities.
• The Surgeon General has determined that there is no safe level of exposure to ambient smoke!

• If you smell even a subtle odor of smoke, you are being exposed to poisonous and carcinogenic chemical compounds!

• Even a brief exposure to smoke raises blood pressure, (no matter what your state of health) and can cause blood clotting, stroke, or heart attack in vulnerable people. Even children experience elevated blood pressure when exposed to smoke!

• Since smoke drastically weakens the lungs' immune system, avoiding smoke is one of the best ways to prevent colds, flu, bronchitis, or risk of an even more serious respiratory illness, such as pneumonia or tuberculosis! Does your child have the flu? Chances are they have been exposed to ambient smoke!
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