Comparative toxicity of various ozonized olefins to bacteria suspended in air

Air containing olefin vapour was treated with known amounts of ozone simulating natural concentrations. The bactericidal effect of the mixture was tested using microthreads sprayed with washed cultures of Escherichia coli var. communis or Micrococcus albus, aerosol strain. With 20 different olefins a wide range of activity was found, those in which the double bond formed part of a ring being the most bactericidal; petrol vapour was about as active as the average open-chain olefin. The two organisms behaved similarly at the experimental relative humidity of 80%. The estimated amount of bactericidal substance present was only about one hundredth of that required to give the same kill with a ;conventional' air disinfectant; a simple physical explanation is proposed for this enhanced effect.

Effects of ozone on the germination of fungus spores

Detached spores of 14 fungi varied in germination after exposure on agar to 10 to 100 parts per hundred million (p.p.hm.) ozone for 1 to 6 h. Large pigmented spores of Chaetomium sp., Stemphylium sarcinaeforme, S. loti, and Alternaria sp. were insensitive to 100 p.p.hm. Spores of Trichoderma viride, Aspergillus terreus, A. niger, Penicillium egyptiacum, Botrytis allii, and Rhizopus stolonifer were reduced in germination primarily by 100 and 50 p.p.hm. for the longer exposures. Small hyaline spores of Fusarium oxysporum, Colletotrichum lagenarium, Verticillium atbo-atrum, and V. dahliae were the most sensitive, as their germination was prevented or reduced by most exposures to 100 and 50 p.p.hm. and occasionally reduced by doses as low as 25 p.p.hm. for 4 and 6 h. Ten parts per hundred million for 6 h had little inhibitory effect, but extended exposures up to 28 h reduced germination of A. terreus, A. niger, and P. egyptiacum spores to below 50% of the controls. The lower doses of ozone sometimes stimulated spore germination. Fungus colonies maintained in an ozone atmosphere had abnormal growth characteristics. Ozone had little inhibitory effect on air-dried spores or spores in a liquid medium.

Ozone: depression of frond multiplication and floral production in duckweed

Plants of Lemna perpusilla #6746 grown in an environment charged daily with a low concentration of ozone over 2 weeks were slower to begin multiplying, had a significantly lower rate of frond doubling, and required longer to produce fewer flowers than control plants. Treated plants produced smaller, slightly yellow fronds but had no symptoms of acute injury. Control plants produced four times as many fronds and six times as many flowers as plants continuously exposed to ozone (0.1 part per million).

Effects of nitrogen dioxide on pulmonary cell population

Studies from this laboratory have shown that ozone produces changes in the number and function of cells obtained by pulmonary lavage. In similar experiments, rabbits exposed to levels of NO(2) from ambient to 60 ppm demonstrated increased numbers of polymorphonuclear leukocytes in the lung washings. This phenomenon persisted for more than 72 hr after a single 3-hr exposure. When streptococci were instilled in the lungs of NO(2)-exposed anesthetized rabbits 30 min before lavage, a pronounced inhibition of phagocytic activity was observed. With these criteria, NO(2) appeared less effective than ozone as a pulmonary irritant.

Plant injury by air pollutants: influence of humidity on stomatal apertures and plant response to ozone

Ozone injury to Bel W3 tobacco and pinto bean plants increases with increasing humidity. The degree of plant injury sustained correlates well with porometer measurements; this indicates that the size of stomatal apertures increases with increasing humidity. Humidity may therefore influence plant response to all pollutants and may account in part for the greater sensitivity of plants to ozone-type injury in the eastern United States compared with the same species of plants grown in the Southwest. with those grown in the Southwest.

In vivo inactivation of lysozyme by ozone

Bronchial mucus contains large quantities of the antibacterial enzyme lysozyme. Acutely exposing mice or rabbits to ozone reduced the amount of active lysozyme obtainable by bronchopulmonary lavage. The effect was proportional to ozone concentration, as well as to duration of exposure. Enzyme activity returned to normal levels during the 12 hr following exposure. Ozone (5 muliters/liter; 5 parts per million) for 3 hr reduced lysozyme levels approximately 30%. Studies of the release of lysozyme by alveolar cells support the theory that loss of activity is due to in vivo oxidation of lysozyme.

Reduction in tobacco pollen germination and tube elongation, induced by low levels of ozone

Pollen of the ozone-sensitive tobacco variety Bel W-3 undergoes a reduction in germination rate and tube elongation when exposed to ozone. As little as 0.1 part of ozone per million for a 5.5-hour exposure period is sufficient to cause a 40 to 50 percent reduction in germination and a 50 percent reduction in pollen-tube elongation. Ozone causes these effects to approximately the same degree whether the pollen is exposed to ozone in vitro or agar disks, or in vivo when the intact plant is exposed. Exposure to ozone at a concentration of 1.0 part per million for more than 3 hours in vitro completely prevents germination of Bel W-3 pollen.