The Bharat Stage (BS) emission standards are regulations set by the Indian government to control the amount of pollutants released by vehicles. They are modeled on the European Euro emission standards. Here’s a detailed explanation of BS3, BS4, and BS6:
1. What Are BS Standards?
Definition:
Bharat Stage (BS) standards define limits for harmful emissions from petrol and diesel vehicles, including:
- Carbon monoxide (CO)
- Hydrocarbons (HC)
- Nitrogen oxides (NOₓ)
- Particulate matter (PM)
Purpose:
- Reduce air pollution.
- Encourage cleaner fuel and advanced engine technologies.
- Improve public health and meet global environmental standards.
Progression: Each stage becomes stricter than the previous one.
2. Overview of BS3, BS4, and BS6
| Standard | Implementation in India | Petrol Emission Limit (CO g/km) | Diesel Emission Limit (NOₓ g/km) | Key Features |
|---|---|---|---|---|
| BS3 | April 2005 | 2.3 | 0.50 | Equivalent to Euro 3; limited technology requirements |
| BS4 | April 2010 | 1.0 | 0.25 | Equivalent to Euro 4; required catalytic converters, low-sulfur fuel (50 ppm) |
| BS6 | April 2020 | 1.0 | 0.08 | Equivalent to Euro 6; required advanced tech like DPF, SCR, EGR; ultra-low sulfur fuel (10 ppm) |
Note: BS5 was skipped to accelerate pollution reduction.
3. Key Differences Between BS3, BS4, and BS6
| Aspect | BS3 | BS4 | BS6 |
|---|---|---|---|
| Emission Limits | Relatively high CO, HC, NOₓ | Reduced CO, HC, NOₓ | Significantly stricter, very low NOₓ & PM |
| Fuel Quality | Sulfur: 350 ppm | Sulfur: 50 ppm | Sulfur: 10 ppm (ULSD – Ultra Low Sulfur Diesel) |
| Technology Requirement | Basic engines, simple catalytic converter | Advanced catalytic converters, improved fuel injection | DPF for diesel, SCR, EGR, better fuel injection & onboard diagnostics |
| Impact on Environment | Moderate pollution reduction | Better air quality | Very significant reduction in NOₓ, PM, and overall emissions |
| Vehicle Cost | Lower | Moderate | Higher due to advanced technology |
4. Technologies Introduced With BS6
- Diesel Particulate Filter (DPF) – traps soot.
- Selective Catalytic Reduction (SCR) – reduces NOₓ using AdBlue/urea injection.
- Electronic Fuel Injection – precise fuel delivery reduces emissions.
- Exhaust Gas Recirculation (EGR) – lowers combustion temperature and NOₓ.
- On-Board Diagnostics (OBD) – monitors emission control systems.
5. Why BS6 Is Important
- India skipped BS5 to improve air quality faster.
- BS6 vehicles emit up to 80% less NOₓ (diesel) and 70% fewer particulates compared to BS4.
- Helps meet global emission norms and reduces smog in cities.
✅ 6. Summary Table
| Feature | BS3 | BS4 | BS6 |
|---|---|---|---|
| Equivalent Euro Norm | Euro 3 | Euro 4 | Euro 6 |
| Fuel Sulfur Content | 350 ppm | 50 ppm | 10 ppm |
| NOₓ (Diesel g/km) | 0.50 | 0.25 | 0.08 |
| PM (Diesel g/km) | 0.05 | 0.025 | 0.005 |
| Tech Needed | Basic | Catalytic converter | DPF, SCR, EGR, OBD |
| Implementation Year | 2005 | 2010 | 2020 |
🔹 In Short
- BS3: Old standard (Euro 3 equivalent), higher emissions.
- BS4: Intermediate standard (Euro 4), lower emissions, cleaner fuel.
- BS6: Current standard (Euro 6), ultra-low emissions, advanced emission control technologies.
Other courses:
