Your favorite pizza selection may be doing more harm to the environment than you think, new research in Brazil suggests.

A team of scientists has explored the causes of air pollution in the city of São Paulo and discovered that pizza joints, steakhouses and other restaurants that use wood-burning stoves are a significant contributor to air pollution.

Emissions From Vehicles

The Latin megacity of São Paulo boasts usage of cleaner biofuel. Researchers found that city inhabitants, which cover about 10 percent of Brazil's population, fill their vehicles with biofuel that contains ethanol, soya diesel, and gasohol (25 percent ethanol and 75 percent gasoline).

Professor Prashant Kumar, lead author of the study and an expert from University of Surrey, says it was evident from their findings that there weren't high levels of pollutants from vehicles in São Paulo compared with other megacities.

However, there has not been much consideration of other possible sources of emissions, including emissions from wood burning in thousands of pizzerias or domestic wood burning.

Pizza Capital

Although feijoada or pork-and-bean stew is Brazil's national dish, pizza is most revered by residents in São Paulo. They celebrate their love for pizza annually every July, with the neighborhood pizzeria becoming the venue for family dinners for most of the inhabitants.

São Paulo is home to approximately 8,000 pizzerias that make a million pizzas per day and can host about 600 people at a time. Anyone can also line up outside pizzerias every Sunday evening.

According to researchers, 800 pizzas a day are produced using old-fashioned wood-burning stoves, while an additional 1,000 pizzas are made for home delivery.

Negative Effects Of Wood Burning

Unfortunately, this sumptuous feasting comes at a cost. Kumar says every month, more than 18.5 acres or 7.5 hectares of eucalyptus forest are burned by steakhouses and pizzerias in São Paulo. In total, this is about 307,000 metric tons or more than 338 U.S. tons of wood sending up emissions annually.

Professor Yang Zhang, a co-author of the study and an expert from North Carolina State University, says once in the air, the burned pollutants can go through complex chemical and physical changes. These processes can create toxic secondary pollutants such as secondary aerosol and ozone.

Kumar said the amount of pollutants created by the city's pizza parlors are enough to become a "significant threat" to the environment.

Details of the study are published in the journal Atmospheric Environment.

How Can We Eat Pizza And Keep The Air Clean?

A town in Italy has tried to address the same problem found in São Paulo.

The town of San Vitaliano outside Naples introduced a new ordinance that bans the use of wood-burning stoves not equipped with filters that decrease air pollutants.

The mayor of the town, Antonio Falcone, has become prominent as the "anti-pizza mayor." Falcone says pizza ovens are not the primary cause of air pollution in his town, but it does give exposure to environmental issues.

"There's an anthropological disaster in play," says Falcone. "The important thing is to make people aware and sensitive."

Photo: Edsel Little | Flickr