Near the ground, it is a noxious pollutant; in the stratosphere, its absorptive ability makes Earth's life possible.

If electricity was produced by photovoltaic cells, directly from sunlight, the air could be freed of the noxious pollutants generated by conventional power plants.

Spider plants, it seems, do much to purify household air of noxious pollutants, like formaldehyde, that can build up to unhealthy levels in a tightly insulated house.

Dead plants form organic sludge, the accumulation of which results in oxygen depletion and release of noxious pollutants such as ammonia and hydrogen sulfide.

The engine, designed by the Cummins Engine Company, emits fewer of the most noxious pollutants and is more efficient than those originally intended for another fuel.

Joined by eight eastern US states and 13 environmental groups, the federal government accused AEP of making major changes to its power plants that drove up noxious pollutants without first getting regulatory approval.

While Europe has managed to drastically cut some, but not all, of the most noxious pollutants over the past 20 years, emerging nations experienced the opposite trend with their fast economic growth, scientists at the UN's meteorological agency said.

The latest focal point was a United Nations Environment Program report on black carbon and ozone (which, besides being a powerful greenhouse gas is a beneficial shield against radiation high in the atmosphere but a noxious pollutant near the ground).

In the end, Mr. Johnson observed that while the motorcycles burned fuel more efficiently and produced lower levels of carbon dioxide than the cars, the noxious pollutants generated by the bikes exceeded the levels generated by the cars.

Describing the proposed new standards as one of the most important steps the EU needs to take in the fight against climate change, environment commissioner Stavros Dimas explained, "These proposals will help achieve a significant reduction in the noxious pollutants from transport that can harm our citizens' health".

The new federal overseer's job title, river navigator, has a Mark Twain ring, while the river, the Cuyahoga, bears an infamous image worthy of Dante: it was the Cuyahoga that burst into flames in 1969 and burned in plain sight of the nation under an oily burden of noxious pollutants.