Try not to be outside when air pollution levels are high.

Pollution levels in the city were five times higher than normal.

Consider keeping your child inside when air pollution levels are high.

As a result, pollution levels have dropped in recent decades.

Do we need to point out once again that chemical pollution levels are still too high?

High pollution levels were also detected in water running off from the fire.

By the 1930s the pollution levels were too high to allow for swimming.

Pollution levels on bridges do not build up because they are open to the air.

The current law does not spell out safe pollution levels.

See if pollution levels where you live could make it hard to breathe today.

This has a strong effect on the pollution levels in the delta.

The lack of large farms in the area and a small population means a low pollution level.

All these factors increased the pollution level in the lake waters.

Studies have shown that pollution levels inside the buses are many times higher than outside.

Later the lake lost some of its glow as pollution levels rose, and we found other places to go.

Some of the measures would be used if new state and local efforts failed to bring pollution levels within legal limits.

The beach had been closed because of unhealthy pollution levels.

Pollution levels in the river are unacceptably high, and something has to be done.

Pollution levels are not related to consumption, but to the state of technology that is applied.

Pollution levels in the whole Carabobo area have increased through the years.

The program imposed a charge on vehicles with higher pollution levels.

But subsequent testing showed that air pollution levels were on the rise again inside the building.

The state of emergency was lifted a few days later after pollution levels had fallen.

The best protection is to avoid outdoor exercise when pollution levels are high.

Use of the fuel is mandated in some other regions with high pollution levels.