* Two-stroke engines mix oil and fuel: This means unburnt fuel and oil are released into the atmosphere, contributing to air pollution.
* Incomplete combustion: Two-stroke engines often have less efficient combustion, leading to more unburnt hydrocarbons being released.
* Lack of catalytic converter: Many two-stroke engines don't have catalytic converters, which help reduce harmful emissions.
However, it's important to note:
* Modern two-strokes are cleaner: Newer designs and technology have significantly improved the emissions of some two-stroke engines.
* Four-stroke engines are not perfect: While generally cleaner than two-strokes, four-stroke engines still produce emissions.
* Maintenance matters: Poorly maintained engines, both two-stroke and four-stroke, will produce higher emissions.
In conclusion: While there are exceptions and advancements in both types, two-stroke engines historically have been known to produce higher levels of air pollution compared to four-stroke engines.
