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How did a road test expose an emissions problem?

A vehicle can perform differently on the road than in a laboratory. In the Volkswagen case, independent emissions measurements raised questions that regulators pursued through further testing. The EPA’s September 2015 account connects the initial anomaly to software that recognized official testing conditions. The discovery depended on following up a mismatch, not simply collecting another passing score.

5–7 min

Questions you could explore

  • Why did the road measurements raise a question that the laboratory result could not answer alone?

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Environment and climate

What can tree rings reveal about past climate?

A tree keeps a record of growth in its wood, but reading that record as climate history takes more than counting rings. Moisture, temperature, and other growing conditions can leave overlapping clues.

4–5 min

What can tree rings reveal about past climate?

Environment and climate4–5 minA tree keeps a record of growth in its wood, but reading that record as climate history takes more than counting rings. Moisture, temperature, and other growing conditions can leave overlapping clues.

Environment and climate

Why can a city be warmer than nearby countryside?

The trip from a leafy edge of town to a dense street can also be a trip between different temperatures. Buildings, pavement, vegetation, and waste heat all affect the balance, and the contrast changes with weather and time of day.

3–5 min

Why can a city be warmer than nearby countryside?

Environment and climate3–5 minThe trip from a leafy edge of town to a dense street can also be a trip between different temperatures. Buildings, pavement, vegetation, and waste heat all affect the balance, and the contrast changes with weather and time of day.

Environment and climate

A trip through a wastewater treatment plant

Water disappearing down a drain begins another journey before it reaches a river or the sea. Uisce Éireann's description of treatment in Ireland separates several different jobs, from screening out objects to biological treatment; the resulting effluent is not drinking water.

4–5 min

A trip through a wastewater treatment plant

Environment and climate4–5 minWater disappearing down a drain begins another journey before it reaches a river or the sea. Uisce Éireann's description of treatment in Ireland separates several different jobs, from screening out objects to biological treatment; the resulting effluent is not drinking water.

How did a road test expose an emissions problem? | Speech Topic | speaking.app