That's an excellent and practical question! As someone who's worked with municipal waste management, I can tell you UV resistance is a major factor in bin longevity. Most modern plastic urban bins are made from high-density polyethylene (HDPE) or polypropylene, which are inherently somewhat UV-resistant. However, "somewhat" isn't enough for years under the sun. Manufacturers add carbon black or specialized UV-inhibiting stabilizers during production. These additives act like sunscreen, absorbing and scattering UV radiation before it can break down the polymer chains.
You'll notice the most durable bins are typically dark colors like black, dark green, or grey. The carbon black pigment is a highly effective UV absorber. Lighter-colored bins can be more susceptible if not properly formulated. Even with additives, prolonged exposure will cause gradual fading and surface embrittlement over 5-10 years. You might see slight chalkiness or minor cracking on the most sun-exposed side. Proper maintenance, like not power-washing with harsh chemicals, helps preserve the protective surface.
For a city planner or facility manager, the key is to specify bins labeled "UV-stabilized" or "for continuous outdoor use." The investment is worth it. A quality UV-resistant bin can last over a decade, while an untreated one might become brittle and crack in just a few years under intense sun. So, to answer directly: they are resistant enough to be practical for long-term urban use, but their lifespan is directly tied to the quality of UV protection engineered into the plastic from the start.