Plastic garbage bags (tall kitchen sized 13 gallon) contain more plastic per square inch than 6 plastic grocery bags (filled), which is about how many you can fit into a 13 gallon tall kitchen garbage bag. So if you ban plastic grocery bags like they did in San Francisco, every household ends up putting even MORE plastic into the landfill with plastic garbage bags than they would have if they'd stuck to the plastic grocery bags to throw away their garbage. Where is the logic? Why didn't the city of S.F. figure this out before banning plastic grocery bags? Am I missing something, or what? Please don't suggest compost bins and the like, city residents, people who live in apartments and other rentals, don't have that option.
Composting is an option. Seattle has compost pickup for all it's citizens. Using plastic bags for your trash is not required. It may help keep your trash can cleaner, but who cares if your trash can is dirty? Just dump it in. Most plastic grocery bags are not reused as trash bags. I applaud you for doing so, but most of them end up either in the landfill or on the side of the road. Some are recycled. Few are reused.
Assuming your calculation is right, you're still making a big assumption--that everyone uses plastic shopping bags as garbage bags. In reality, a lot of people use both plastic shopping bags and garbage bags; the plastic shopping bags either don't get reused or get reused a few times until they wear out and then are thrown away. (Or worse, they become litter.) So if that calculation of yours is right, then *you* might end up disposing of more plastic. But on the whole, plastic garbage would be reduced.
According to various sources around the web: There are an estimated 500 billion to 1 trillion plastic bags consumed worldwide each year. That comes out to over one million per minute. Billions end up as litter each year. These billions that are draped on trees and bushes and blowing around our streets, deserts, mountains and beaches are perhaps an even bigger problem than the amount of plastic that ends up in landfills. I imagine in Coastal communities like San Fran, they are also concerned with the marine life that is injured, tortured and killed by this waste product. According to the nonprofit Center for Marine Conservation, plastic bags are among the top 12 garbage items most often found in coastal cleanups. In Ireland an extremely successful plastic bag consumption tax, or PlasTax, introduced in 2002 reduced consumption by 90%. Approximately 18,000,000 liters of oil have been saved due to this reduced production. Governments around the world are considering implementing similar measures. My full article on this subject referenced below.
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