Putting an impossible amount of material down in a municipal parking area and then eyeballing which sweeper leaves behind the smallest pile is essentially senseless when choosing a sweeper for environmental reasons. However, don’t rely solely on the certification process developed when California’s South Coast Air Quality Management District (SCAQMD) was required in the 1990s to reduce airborne pollution in its jurisdiction.
Manufacturers widely use the district’s so-called PM10 Sweeper Certification to tout their machines as effective environmental sweepers. Over time, they’ve found ways to certify virtually any design. More than 50 makes and models, almost every type and configuration on the market, comply with the SCAQMD test, rendering any given machine’s compliance essentially meaningless.
There’s no Consumer Reports for street sweepers other than manufacturer literature, but there are articles that will help you conduct a real-world performance test that makes sense given the type of debris, roadway condition, and other factors your department faces.