Slower international trade due to the faltering economy is helping the ports of Los Angeles and Long Beach as they implement their new Clean Trucks Programs, though there are concerns about bottlenecks developing, according to a report released Friday.

Cargo volume at the nation’s major retail container ports fell again in October allowing the two Southern California ports to operate smoothly despite the banning of all trucks built prior to 1989 at the beginning of the month, according to the monthly Port Tracker report by the National Retail Federation and consultant IHS Global Insight.

“Retail sales forecasts this year are the lowest they’ve been in more than half a decade, and the cargo volume we’re seeing reflects those numbers,” said Jonathan Gold, NRF vice president for supply chain and customs policy, in the report.

However, the report warns that congestion could develop this month once the two local ports starts collecting fees associated with the clean truck program, though it’s expected there will be an adequate number of trucks to handle import traffic.

The Clean Trucks program is intended to improve air quality by banning older, more polluting trucks and replacing them with late-model and alternative-fuel vehicles over a four-year period.

The plan is being fought in court by the National Trucking Association, which opposes concessions motor carriers must now obtain to service the port. The Federal Maritime Commission has sided with the industry in the legal battle, also seeking to strike down the concession requirement.