PHOTOS: Earth Day Evolution

<div class="meta image-caption"><div class="origin-logo origin-image ap"><span>AP</span></div><span class="caption-text">In this April, 22, 1970 file photo, a Pace College student in a gas mask &#34;smells&#34; a magnolia blossom in City Hall Park on Earth Day, April 22, 1970, in New York. </span></div>
April 22, 2010 9:44:15 AM PDT