The evolution of Emission Regulations
Both Europe and the USA have played major roles in implementing regulations on automotive NOx emissions. The US Clean Air Act of 1970 was the first major legislation targeting vehicle emissions, including NOx.
Since the early 1990s they both implemented progressively stricter “EPA Tier” and “Euro” standards. Each new stage tightening the rules for what vehicles were allowed to emit.
Selective Catalyst Reduction (SCR) with AdBlue Diesel Exhaust Fluid became mandatory as the standards became stricter:
- First for heavy-duty vehicles in Europe under Euro IV and V from 2005-2006
- Then it was effectively required for US trucks under EPAs stringent NOx limits from 2010
- And for light-duty vehicles under Euro 6 from 2014-2015
Today, nearly all new diesel vehicles and machinery re fitted with SCR. Without AdBlue, these vehicles cannot legally operate.
Next up is EPA’s Ultra-Low NOx in the US from 2027 and Euro 7 for heavy-duty vehicles in Europe in 2028-2029.
AdBlue Diesel Exhaust Fluid becoming global
Beyond USA, Canada and Europe major countries across the world have adopted the same or similar legislation:
- South Korea, Turkey, Japan, Singapore, Hong Kong and Taiwan have already had Euro VI (or the equivalent PPNLT in Japan and Singapore) since before 2020
- India has had Euro VI equivalent Bharat VI since 2020
- China has had similar strict levels under China VI a) and b) since 2021
- Brazil has had similar strict levels under its PROCONVE P-8 since 2022
- Colombia, Australia (ADR 80/04) and Mexico (EPA 2010) adopted Euro VI in 2023, 2024 and 2025, respectively
- Russia is on Euro V and Indonesia on Euro IV
In 2025 the Climate & Clean Air Coalition (CCC, a United Nations Environment Programme) recommended a global shift toward Euro 6/VI vehicle standards and a minimum requirement of Euro 4/IV - which is the minimum vehicle certification that requires AdBlue diesel exhaust fluid to achieve the required NOx emissions removal.
Beyond road transport vehicles, SCR and AdBlue has gained broader coverage, including all non-road mobile machinery including farming and forestry; mining and civil engineering machinery.
This way, modern diesel engines with AdBlue offer a sustainable low-emission bridge to existing or future zero emission replacement.
Why regulations are so important
Regulations are not only about protecting health — though that is the main driver. They also ensure:
Fair competition
All vehicle manufacturers must meet the same requirements.
Continuous innovation
Stricter rules push companies to develop better engines and exhaust systems.
Climate progress
With SCR and AdBlue® controlling the NOx – auto makers can focus on driving up fuel efficiency lower CO₂ emissions.
Public trust
Scandals like “Dieselgate” showed what happens when rules are ignored. Strict testing keeps industry accountable.
