Caused by pollution from cars, power stations, even paint solvents.

Known as Peking throat and caused by pollution, it happens anywhere, anytime.

The area, relatively untouched by pollution, attracts summer and winter tourism.

With few cities nearby this is probably one of the places least affected by light pollution.

Was there such a thing as death by pollution?

If that rose even to 1.5, travel times would drop by nearly a quarter and pollution by around a fifth.

The baiji sought fish that have been netted or driven from the river by pollution.

In the 1970s people began to notice how much damage was being done to all that area by pollution.

He said the tunnel would reduce overall truck traffic in the city by a much larger amount, cutting road congestion and pollution.

Its white walls are faded throughout; blackened by pollution and neglect.