ABSTRACT
This chapter considers the influence of smoke, fog and sunlight in the prevention and treatment of disease. The effect of fog and smoke in the air is due in part to its direct irritating effect, and in part to its shutting off the rays of the sun. The effect of a few days of smoky fog in increasing the death rate in the following week, especially from bronchitis and other respiratory affections, is well known. In 1889 Huntley and in 1900 Palm published articles lauding sunlight as a preventive of rickets. In 1819 Raczynski published the first experimental evidence of the physiological effect of the sun. The separate influence of the invisible ultra-violet part of the spectrum was stated by Huldschinsky in 1919, who showed that rickets could be prevented or cured either by irradiation with sunlight or by exposure to the quartz mercury lamp.
