Al Qusais apartment AC keeps struggling — is the dust off the road and flight path making it worse?

You're not imagining it. Dust doesn't damage a sound AC, but it's the single biggest reason cooling fades between services, and areas like Al Qusais with heavy road traffic and an industrial edge load the filters and coil far faster than a quiet villa community. A choked filter starves airflow, then the fine dust that gets past it settles on the evaporator coil and acts like a blanket, so the unit runs longer and colder-starved to hit the same temperature, which is exactly the fading you're seeing. The fix isn't a repair, it's interval: in a dusty pocket, check and rinse the filters roughly monthly through summer instead of quarterly, and get the coil professionally cleaned more than once a year. Booking AC maintenance in Al Qusais on a slightly tighter schedule than the standard once-a-year will hold the efficiency far better than any one-off fix. A better-grade washable filter helps, but never a denser filter than the unit is rated for, that just chokes airflow a different way.