Will Planting Trees In Our Garden Make The Air Cleaner?

Trees have, since the Industrial Revolution, been referred to as the Earth's lungs.  This is because they produce oxygen, take in carbon dioxide which is a major pollutant and they filter harmful particles such as those from diesel vehicles.
But within the domestic setting it would be practically impossible to plant enough trees to make a significant difference to the quality of air in your garden.
However, it is possible to start big things with one little step and if every person planted two or three trees in their garden  then this could actually make a difference.  So it may be worth planting as many trees as you can and encouraging friends and relatives to do the same.  
Remember to check how tall the tree grows before planting and the extent of the roots.  If trees are grown too near a house, their roots can end up damaging the foundations of the house, which will incur significant costs to put right.  

No but they will create giant tacos