Freshly fallen snow makes your backyard took clean and bright. But how clean is that snow? If you live in a city, it may contain particles of pollution. Even snow in rural areas may have some contaminants, as air pollution can travel many miles.
Collect about ten cups of fresh snow and let it melt.
Cover the mouth of a measuring cup or jar with a paper towel or coffee filter.
Then pour the snowmelt through the filter.
Examine the filter paper for tiny particles – you might want to use a hand lens to get a better look. How clean was your snow?
For further investigation you can measure the amount of pollution in your snow. Weigh a filter paper before you pour the melted snow through it. Let it dry with the particles and weigh it again (you’ll need a sensitive scale).
You can also compare snow from different areas: an area with lots of traffic, a field far from a city, your school playground, neighborhood parks.