Study: Pollution from agricultural fires dangerous to infant health

Burning sugarcane fields in Queensland, Australia. (Credit: Edgar Crook/Flickr)

Pollution is not just a plague of industrialized cities. Relatively low levels of pollution from traditional crop-burning methods used across the developing world can harm infant health, according to recent research.

The study, conducted by researchers at Princeton and Duke universities, looked at the health effects of pollution from controlled fires that burn across Brazil’s São Paulo state during the sugarcane-harvesting season. Exposure to even small levels of pollution from the fires in the last few months of gestation led to premature birth, lower birth weights and increased fetal mortality.

“Our findings suggest that small increases in air pollution can damage early-life health even in relatively unpolluted areas … [yet] the pollution levels in our study are virtually ignored by environmental agencies across the globe,” the authors wrote in the report.

Brazil increased sugarcane production in response to a rising demand for sugarcane ethanol, which is ironically used as a renewable fuel source across the country. According to the report, Brazil is the world’s leading producer of the crop, and São Paulo state accounts for more than two-thirds of the national production.

The researchers said many Brazilian farmers use a traditional approach to harvesting sugarcane, burning the fields to remove straw and other materials and leaving the cane to be cut by hand. These techniques have been used for thousands of years and are still widely used across the developing world, notably in sub-Saharan Africa.

This map shows the average share of each 0.25 longitude by 0.25 latitude square that burned annually from 1997 to 2004. The researchers’ study site is located in south-central Brazil, where a regional hot spot in fire activity can be seen. (Map source: Global Fire Emissions Database, http://www.globalfiredata.org/)

This map shows the average share of each 0.25 longitude by 0.25 latitude square that burned annually from 1997 to 2004. The researchers’ study site is located in south-central Brazil, where a regional hot spot in fire activity can be seen. (Map source: Global Fire Emissions Database, http://www.globalfiredata.org/)

Tom Vogl, the study’s author and assistant professor of economics and international affairs at Princeton, explained that he and co-author Marcos Rangel chose São Paulo because the right data sets were available. The researchers measured the impact of fire pollution by gathering information from satellites, pollution monitors and birth records obtained by the Brazilian government.

“For much of the developing world, we don’t have great data on children’s birth outcome,” Vogl said in an interview with Humanosphere. “We don’t have great data on pollution levels – or, for that matter, on wind direction, which is key to our study’s design. This context presented a really great opportunity to bring really high frequency and granular data to the issue.”

The report suggests that policymakers in Brazil and across the developing world pay more attention to the negative health impact of pollution from agricultural fires, which has typically been considered negligible compared to industrialized centers like New Delhi or Beijing.

Paradoxically, the researchers note that these same fires bring economic opportunities to many people, including parents, which can lead to better health outcomes for children. In a summary of the study on Princeton’s website, Rangel said sustainable development policies should consider the trade-offs between these economic and environmental goals.

Other research on agricultural fires has documented its impact on the climate, particularly the Arctic, which receives a significant portion of the black carbon released from burning biomass in lower latitudes. The Arctic has been warming at twice the rate of the rest of the planet, leading to rising sea-levels, coastal flooding, and insecure water supply – all which disproportionately impact the world’s poorest.

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Lisa Nikolau

Lisa Nikolau is a Madrid-based reporter for Humanosphere, covering gender equality, indigenous rights and poverty in Latin America and worldwide. Find her on Twitter at @lisanikolau, email lisa.nikolau@humanosphere.org or see her latest work at www.lisanikolau.com