"These polluting nanoparticles are so tiny that they behave like gas molecules. When inhaled, they can penetrate the respiratory system's defensive barriers and reach the pulmonary alveoli, so that potentially toxic substances enter the bloodstream and may increase the incidence of respiratory and cardiovascular problems," said Professor Paulo Artaxo at the University of São Paulo's Physics Institute (IF-USP) and a co-author of the study.
He says that between 75 percent and 80 percent of the mass of nanoparticles measured in this study corresponds to organic compounds emitted by motor vehicles. Levels of ultrafine particulate matter in the atmosphere are neither monitored nor regulated by environmental agencies anywhere in the world, Artaxo says.
"What these compounds are, exactly, and how they affect health are questions that require further research." The São Paulo State Environmental Corporation (CETESB), for example, routinely monitors only solid particles with diameters of 10,000 nm (PM10) and 2,500 nm (PM2.5), as well as other gaseous pollutants such as ozone (O3), carbon monoxide (CO) and nitrogen dioxide (NO2).
Nonetheless, he explains that a consensus is forming in the United States and Europe based on recent research indicating that these emissions are a potential health hazard and should be regulated. Several U.S. states, such as California, have laws requiring a 20 percent-30 percent ethanol blend in gasoline, which also reduces emissions of ultrafine particulate matter.
