How does the Audi A8's nitrogen oxide reduction system work?

I've read that nitrogen oxide emissions from diesel engines are harmful, but I've also heard that the Audi A8 has a reduction system. Can you explain how it works and how effective it is?

The Audi A8's nitrogen oxide reduction system uses a combination of selective catalytic reduction and a particulate filter to reduce emissions. By injecting AdBlue, a harmless liquid, into the exhaust, the system converts nitrogen oxide into nitrogen and water. This helps to significantly reduce harmful emissions.

After years of development and testing, Audi has perfected its nitrogen oxide reduction system. It works by capturing the emissions in a catalyst, where they are chemically transformed into harmless substances before being released into the atmosphere. This advanced technology ensures that the Audi A8 meets the strictest emissions standards.