Some epidemiologic evidence implicating air pollutants as a factor in induction or aggravation of allergic diseases such as allergic rhinitis or asthma was reported. In this paper, we have reviewed animal studies on the effects of NO₂, O₃, fly ash and diesel exhaust on immune response. Exposure to low concentrations of NO₂ in ovalbumin (OA) primed mice significantly enhanced antigen-specific IgE antibody production. O₃ exposure modulated immune response. Intranasal instillation with fly ash or diesel exhaust particulates mixed with OA markedly increased anti-OA IgE antibody production. Moreover, diesel exhaust inhalation increased both anti-OA IgE antibody and interleukin-4 productions. These results implies that air pollutants potentiate immune response via modulation of cytokine production in mice.

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It was known that mutagenic compounds were produced by combustion of various fuels such as gasoline and diesel oils for cars, coal for power plants and wood or oil for warming and incineration of various wastes. Polyaromatic hydrocarbons (PAHs) were well known as typical mutagenic compounds produced by incomplete combustion. But there are few reports about the characteristics of mutagenic compounds produced by combustion of the fuels and incineration of the wastes.
In this report, the characteristics and control methods of mutagenic compounds from waste incinerations, cars and combustion of coal, wood and others were discussed.
Higher mutagenicity in exhaust gas from the waste incineration was observed under the condition of incomplete combustion. Not only PAHs such as fluoranthene and benzopyrene but also many chlorinated PAHs, and alkylated PAHs were produced from the waste incineration, and they might contribute much to mutagenicity of the exhaust gas from the waste incineration.
Meanwhile, nitrated PAHs having high mutagenicity were produced from car engines. Alkylated nitrophenanthrene, polyaromatic ketones, alkylated PAHs and others were formed by the combustion of coal, wood and straw.
The emission of these mutagenic compounds could be decreased by properly using good furnace and secondary combustion chamber, selection and clean up of wastes or fuel, or treatment of exhaust gas by catalyzer. It needs that research and development on the methods for monitoring and controlling mutagenic compounds formed by combustion and incineration.

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The semibatch reactions of NO₂-NO-N₂-aqueous solution systems were studied at 1.5×10²<P_NO2<6.2×10² Pa and 0.4<P_N0<5.1 Pa and the changes of concentrations in aqueous solution of [NO₂^-] and [NO₃^-] with respect to exposure time were examined. On the basis of the absorption rates, measured with respect to exposure time, the reaction kinetics were estimated. The reactions proceeded with the following mechanisms.
N₂O₄ (g) (2NO₂ (g)) +H₂O (1) =2H⁺+NO₂^-+NO₃^-
NO (g) +NO₂ (g) (N₂O₃ (g)) +H₂O (1) =2H⁺+2NO₂^-
↓
3/2N₂O₄ (g) (3NO₂ (g)) +H₂O (1) =2H⁺+2NO₃^-+NO (g)
NO₂^-+NO₂ (g) =NO₃^-+NO (g)
The reactions described here were assumed to proceed in parallel, and the rate constant of aqueous-phase reaction [A4/1], N₂O₄ (a) (2NO₂ (a)) +H₂0 (1) =2H⁺+NO₂^-+NO₃^-, was determined by experimental data in the region of diffusion controlling and the rate equation proposed by Danckwerts. It could be represented by 1.85 [H⁺] ^-0.20. When NO₂ (a) and N₂O⁴ (a) coexist in the aqueous solution, this correlation can be applied to estimate the rate constant k_A4/1 in the pH region of 5-13.

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Decomposition method on chlorofluorocarbons (CFCs) in cement kiln is one of the thermal oxidation technologies recommended by the United Nations Environment Programme (UNEP). The decompition of CFC12 recoverd from old refrigerators has been studied in a test plant of small-sized cement kiln.
CFC12 was completely decomposed in the kiln operated under nomal conditions. Emissions of hydrogen fluoride and hydrogen chloride in the flue gas were lower than 0.06 ppb. No formation of toxic halogenated organic compounds like polychlorinated dibenzo-p-dioxins or dibenzofurans was observed in the CFC12incineration.

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To investigate the effects of ambient levels of O₃ on growth, gas exchange rates and chlorophyll contents of three-year-old seedlings of Fagus crenata Blume, the seedlings were exposed to 75 or 150 nl·l^-1 (ppb) O₃, 6 hrs a day (10:00-16:00), 3 days per week, for 18 weeks from 16 May to 18 September 1994 in controlled-environment growth cabinets. The exposure to O₃ caused a reduction in the dry weight growth of the whole-plant or roots, but did not change the leaf areal growth of the seedlings. The net photosynthetic rate of the seedlings exposed to O₃ was reduced without a significant change in the gaseous phase diffusive conductance to CO₂ of the leaves, which shows that this reduction was not due to stomatal closure. The analytical results of the CO₂-response curves of the photosynthesis in the O₃-exposed seedlings suggested that the regeneration rate of RuBP and the activity and/or amount of Rubisco were reduced by the O₃ exposure. Furthermore, the chlorophyll contents of the O₃-exposed seedlings were less than those of the control seedlings just after the end of the growth period of 10 or 18 weeks. From the results obtained in this study, it was concluded that the dry weight growth, net photosynthetic rate and chlorophyll contents of F. crenata seedlings are detrimentally affected by the ambient levels of O₃.

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Concentration of ozone was measured from August 19 to 20, 1995 near the summit of Mt. Maeshirane (2, 377 m) at the altitude of about 2, 320 m. An electro-chemical ozone sensor working by batteries and solar panels was used with a small data logger. High concentration of ozone up to 109 ppb was observed. Ozone concentration was high when wind blew from south east. The concentration of ozone was much lower at a nearby field station (near Yumihari Pass, altitude of about 1, 450m), around which forest damage is not observed. It indicates that ozone is one of the most important causes of forest dieback observed around Mt. Shirane.

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