Environmental control and public health  introduction/ 
 T237 Units 1 and 2  technology  
environmental control and public health course team. 
 - England :  Open university,   1992. 
 - 63 p. :  ill. ;  29 cm. 
<br/><br/><label>ISBN: </label>0749261692 (pbk.) 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Unit 2 : biology. <br/>Unit 1 : pollutants and pollution control.