Aerobiology documents the proceedings of the Third International Symposium held at the University of Sussex, England, in September 1969. The book is organized into three chapters that correspond to the three sessions held during the symposium. These three sessions dealt with themes of airborne infections in closed and segregated environments; the value and use of germ-free environments; and physiological and genetic factors in host resistance. Examples of the contributions during these sessions included studies on the transmission of meningococci among Army recruits; the transfer and acquisition of micro-organisms between and by patients nursed in a uni-directionally ventilated environment and those in an open ward; and the association between blood group status and susceptibility to certain virus infections. The symposium also included seminars that focused on the following themes: intramural spread of infection; laboratory safety; the immunological aspects of pathogenesis; vaccines and vaccination methods; microbial survival in air; rapid diagnosis; techniques in aerobiology; and the ways in which airborne particles cause infection.