7/2: Green Fireworks for the 4th: It's possible! While traditional fireworks pollute the atmosphere, newer developments have been made to reduce pollutants.

Source: 'Green' fireworks may brighten eco-friendly 4th of July displays in future
http://www.eurekalert.org/pub_releases/2009-06/acs-fm062209.php

Fireworks, flares and other so-called "pyrotechnics" traditionally have included potassium perchlorate as the oxidizer, a material that provides the oxygen that fireworks need to burn. Perchlorate, however, is an environmental pollutant with potential adverse effects on people and wildlife. Pyrotechnics contain other ingredients, such color-producing heavy metals, with a similar potential.

Studies have shown that perchlorate from community fireworks displays conducted over lakes, for instance, can lead to perchlorate contamination of the water. For full details about how perchlorate contaminates lakes after fireworks displays, Click here for a study published in the American Chemical Society's peer-reviewed journal, Environmental Science & Technology.

Researchers, however, have developed new pyrotechnic formulas that replace perchlorate with nitrogen-rich materials or nitrocellulose that burn cleaner and produce less smoke, according to an article in ACS's weekly newsmagazine, Chemical & Engineering News (C&EN).