Fort Pitt Tunnel (Credit: Doug Kerr, via Flickr/CC BY-SA 2.0)
Scientists have found that for every particle of pollution directly produced by a vehicle, approximately ten times that amount of pollution is produced by the original particle’s reactions with its environment.
Allen Robinson of Carnegie Mellon University collected air from Fort Pitt Tunnel, Pittsburgh, where about 61,000 vehicles pass daily. A tube through a tunnel ventilation slit introduced the vehicle emissions to a potential aerosol mass flow reactor, where hydroxyl radicals oxidized volatile organic compounds produced by the vehicles, mimicking reactions with the atmosphere.
About ten times more secondary organic aerosols resulted post reaction versus primary organic aerosols, according to mass spectrometry. The finding is important, as most particulate matter regulations only target direct emissions.
Image: Fort Pitt Tunnel (Credit: Doug Kerr, via Flickr/CC BY-SA 2.0)