Issue Date: October 28, 1970
City: San Clemente, CA
Quantity: 40,400,000
Printed By: Bureau of Engraving and Printing
Printing Method: Photogravure
Perforations: 11 x 10 ½
Color: Multicolored
This issue of four different stamps, originally printed as a se-tenant, focused attention on the need for pollution control and made it clear that only a massive effort would help in solving the perilous pollution problems in our air, water, soil, and cities.