Emissions from aircraft and shipping are anticipated to be the dominant sources of increases in ground-level ozone, which can trigger respiratory disease.

Didier Hauglustaine and Brigitte Koffi of the Laboratory of Climate and Environmental Sciences in Gif-sur-Yvette, France, used a global climate model to calculate the relative contributions of road transport, aircraft and shipping to the projected increase by 2050 in ozone pollution in Europe and the United States.

Nitrogen oxide emissions from aircraft will contribute more than 30% of the transport-induced increase in peak summertime surface ozone. Shipping emissions will, in some regions, account for up to 60% of the increase. Thanks to cars becoming cleaner, road transport will probably contribute little.

Geophys. Res. Lett. http://dx.doi.org/10.1029/2012GL052008 (2012)