Researchers tracked air pollution at 15 monitoring sites across New York City during the first year of the country’s first congestion pricing program.

Fine particulate pollution inside the congestion zone fell about 13 percent beyond what regional trends, weather and year-to-year variability would predict.

The decline closely matched the roughly 11 percent drop in vehicles entering the zone, though pollution had already been falling citywide for other reasons.

Nitrogen dioxide dropped more than 20 percent across the metro area, but the study could not attribute that regional decline to congestion pricing.

A research team has found that changing what the United States exports to China could substantially reduce the environmental impact of agricultural trade. 

The size distribution of marine primary organic aerosols, the organic component of sea spray, has been measured for the first time down to 35 nanometres from long-term observations in clean North Atlantic air. It is bimodal, whereas the parameterization in major climate models is unimodal and underestimates particle number threefold. The resulting underestimate in cloud condensation nuclei reaches 16 to 64 per cent at marine supersaturations, assuming 30 per cent lower surface tension.

An instrument built to study cosmic rays has turned out to be a powerful tool for investigating thunderstorms. Earlier observations with the GRAPES-3 muon telescope revealed that thunderclouds can develop electrical potential differences far greater than those ever measured directly. But they also uncovered a puzzle: the instrument detected many more thunderstorm events in the eastern part of its field of view than in the western part. A new study by the same team, published in JCAP, has now explained why. The asymmetry does not mean that thunderstorms are actually more common to the east. Instead, it arises from the way the geomagnetic field affects the cosmic rays travelling through Earth’s magnetosphere, making GRAPES-3 more sensitive to thunderstorms from some directions than others. The result strengthens the case for using these cosmic-ray particles as a natural probe of thunderstorm electricity.

A new study published in Advances in Atmospheric Sciences finds that tropical cyclone activity and coastal hazard along East Asia have been shifting steadily northward.