How does it fight pollution?
Normally, storm water is naturally filtered through soil before it reenters the water system. Paved surfaces however, block storm water from being filtered. Storm water usually gets piped to the nearest body of water along with all the surface pollutants like oil drips, brake dust, litter and other water pollution.  Porous pavement allows storm water to pass through the surface, eliminating storm water runoff and keeping pollution out of our waterways. 

More information
The key to success with porous pavement is to keep the pores open. It’s imperative to avoid sealing the pavement with nonporous sealants and to keep the pavement free of debris.

Cleaning the pavement with just the nozzle from a high-powered, pure vacuum sweeper three or four times a year usually does the trick. Porous pavement varies depending on your local climate, so talk to a specialist in your area.

More resources:
Interlocking Concrete Pavement Institute 
National Ready Mixed Concrete Association 
National Asphalt Pavement Association

Porous Pavement
Porous pavement, or pervious pavement, is a special type of Portland cement concrete or asphalt concrete that is porous and allows water to pass through it. Paving bricks may also be used, but oftentimes the water and storm water passes through the permeable course sand that is between the bricks. Regardless of the top surface type, all pervious pavement types intended for storm water control are designed to allow water to pass through the top surface, then store and begin to filter the storm water in some type of collection bed under the top surface layer. The stored storm water can be absorbed directly back into the soil, virtually eliminating storm water runoff.