You can also view previously answered questions in the HSW Question Archive . So if your mother has you haul everything to a sunny spot on the driveway so that it gets several hours of strong sunlight, she is using the sun to disinfect things. It turns out that ultraviolet light gets used as a disinfectant in a number of different products. For example, you can buy swimming pool systems that disinfect the water in the pool by running it past a strong UV light.
Some municipalities do the same thing to augment the chlorine that treats drinking water.
In third-world countries, there have been experiments using clear plastic soda bottles filled with contaminated drinking water. People leave the bottles in the sun and it actually helps to reduce bacteria in the water. See, for example, this page . There might be other reasons your mother has as well. If you go back in time a century or so, there were no vacuum cleaners.