Bolivia's Air Pollution Crisis: Understanding The Causes

Bolivia's air pollution is a growing concern, with the country's annual mean concentration of PM2.5 exceeding the recommended maximum. La Paz and El Alto, two fast-growing, high-altitude cities, are major contributors, with sources of particulate matter including vehicle emissions, oil refineries, and household and agricultural waste burning. The dry season, from May to November, sees higher levels of air pollution due to agricultural fires. La Paz, El Alto, and Cochabamba consistently have high levels of air pollution.

The health risks associated with air pollution are significant, including breathing problems, chronic diseases, and increased hospitalization and premature mortality. The concentration of particulate matter (PM) is a key indicator, with fine particles (PM2.5) being more harmful as they can travel deeper into the cardiopulmonary system. The World Health Organization recommends annual mean concentrations of PM2.5 and PM10 not exceeding 10 µg/m3 and 20 µg/m3, respectively.

Vehicular emissions

The ensemble of vehicular emissions sources (exhaust and non-exhaust) account for 35% and 25% of the measured particulate matter in La Paz and El Alto, respectively. The non-exhaust vehicular emissions are identified by the presence of metals such as copper, tin, antimony, and lead, along with a significant contribution of iron in terms of mass. These metals are tracers for brake and tire wear, which is generated by vehicles through mechanical abrasion.

The influence of vehicular emissions is further exacerbated by the absence of restrictions on the age of the vehicle fleet in Bolivia. Statistics indicate that 43% of the circulating vehicles are less than 10 years old, 15% are 10-20 years old, and another 24% are 20-30 years old. This means that a large portion of the vehicle fleet in Bolivia is older, which can contribute to higher emissions and poorer air quality.

To improve air quality in Bolivian cities, regulations on vehicular emissions need to be strengthened. As the metropolitan areas continue to grow, more efficient means of transportation and stricter policies on combustion practices are necessary to prevent further degradation of air quality.

Oil refineries

In Bolivia, the integration of its agriculture into international commodity markets has increased the demand for Bolivian agricultural products. This has resulted in the establishment of industrial-scale soybean plantations, particularly by foreign landowners, contributing to the country's rapid deforestation and further exacerbating air pollution.

Household waste burning

Nitrogen oxides (NOx) are a group of nitrogen compounds that contribute to global warming, ozone depletion, and smog formation. They are also responsible for acid rain. Volatile organic compounds (VOCs) are carbon-based compounds that react with sunlight when released into the atmosphere, forming other compounds, such as ozone, that contribute to smog. Carbon monoxide (CO), another product of burning garbage, is a significant greenhouse gas that affects air quality and can impact a region's ability to meet clean air standards.

Particle pollution, or particulate matter (PM), refers to the fine particles produced by burning trash that reduce visibility and create haze. These particles can carry dangerous chemicals, such as dioxins, and have negative health effects, particularly for individuals with respiratory conditions like asthma. Additionally, the smoke from burning household waste can contain harmful chemicals like arsenic, lead, and benzene, which can be released into the air or remain in the ash.

The specific chemicals produced during waste burning depend on the composition of the trash, the temperature of the fire, and the available oxygen. Plastics, polystyrene, treated wood, and bleached or colored papers can release toxic chemicals when burned. For example, burning CCA pressure-treated wood can release arsenic into the smoke or leave it in the ash, posing risks to human health and the environment.

The impact of household waste burning on air pollution extends beyond the immediate vicinity of the fire. A study by the US Environmental Protection Agency, the NYS Department of Health, and the NYS Department of Environmental Conservation found that burning trash in a household barrel can produce as much air pollution as a modern, well-controlled incinerator burning 400 times more trash per day. Furthermore, Bolivia's air quality data from 2017 to 2023 shows that the country's air pollution levels have consistently exceeded the World Health Organization's annual air quality guideline values, indicating a persistent issue with air pollution in the country.

Agricultural waste burning

The burning of agricultural waste releases smoke, a complex mixture of carbon, tars, liquids, and different gases. This open combustion source produces particles of widely ranging sizes, depending on the rate of energy release from the fire. These particles, particularly those smaller than 2.5 micrometers, can penetrate deep into the lungs and cause serious health problems. Exposure to particulate pollution has been linked to increased hospital admissions, emergency room visits, and respiratory symptoms in children.

In Bolivia, the expansion of agricultural activities in the eastern and Amazonian lowland areas has led to an increase in fires, contributing to the country's air pollution. This is further exacerbated by the country's progress and expanded road construction, which provides enhanced access for illegal loggers to forested regions.

To address the issue of agricultural waste burning and its impact on air quality, the U.S. Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) have collaborated to improve air quality and ensure a healthy environment. Their efforts include refining the distinction between wildland fires and agricultural burning, as well as working with the agricultural community to address emissions from agricultural burning.

Seasonal variations

Bolivia's air pollution is subject to seasonal variations, with higher levels of air pollution during the dry season (May to November) due to agricultural fires. The yearly alternation between the dry and wet seasons shows an annual maximum of PM10 concentrations coinciding with the middle of the dry season (Southern Hemisphere winter). During this season, negligible wet deposition occurs, and favourable conditions for particle resuspension are prevalent. Maximum daily ambient PM10 concentrations of 37.2±10.5 and 33.2±7.5 µg m−3 were measured during this period (May–August) in El Alto and La Paz, respectively. Conversely, the wet season (Southern Hemisphere summer from December to March) exhibits frequent precipitation events and the highest daily minimum temperatures.

Among all the samples collected during the measurement campaign, 5% and 12% of the daily samples collected in La Paz and El Alto exceeded, respectively, the 24-hour PM10 concentration of 45 µg m−3, which is not to be exceeded for more than 3–4 days per year, according to the short-term PM10 air quality guideline (AQG) level recommended by the World Health Organization (WHO).

The annual PM10 concentrations in both cities are at least 1.2 times higher than the PM10 maximum yearly average exposure levels of 15 µg m−3 recommended in the annual AQG by the same organisation (WHO). Average measured PM10 concentrations were found to be 29.9±12.0 µg m−3 (STP 49.6±19.9 µg m−3) in El Alto and 27.2±8.9 µg m−3 in La Paz (STP 43.5±14.2 µg m−3).

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