The collaborative research between NIES and CENICA/UAM has been conducting from 1996 :

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1 Present status of air pollution in Japan and Photochemical Air Pollution Research Project in CENICA -Comparison study between Tokyo and Mexico City- Shinji Wakamatsu Leader, Urban Air Quality Research Team, Regional Environment Division National Institute for Environmental Studies Onogawa 16-2 Tsukuba,Ibaraki,35-53 Japan Tel , Facsimile , 196~ Industrial air pollution SO2, Dust 197~ Photochemical air pollution SPM(Suspended Particulate Matter) PM1,PM2.5, DEP(Diesel Exhaust Particle) Secondary Aerosols 198~ Long Range Transport of Air Pollution from Chinese Continent. Increase in Acid Deposition and Tropospheric Ozone,due to the emission increase in east Asia.(SOx,NOx,VOCs) The collaborative research between NIES and CENICA/UAM has been conducting from 1996 : The major purposes of this joint research were to investigate the urban photochemical air pollution formation mechanisms based on model simulation and field analysis both in Mexico City and Tokyo metropolitan areas. SPM (Suspended Particulate Matter) PM1,PM2.5,Secondary Aerosols will be also increase. CO2 emission is also increasing in east Asia. Mexico Mexico City Mexico City is located at the altitude of 224m above mean sea surface and surrounded by higher mountain region of 4-5m. This area is covered by highpressure system throughout the year and subsidence inversion is frequently observed aloft. Ozone trend in Mexico City Ozone concentration level in Mexico City has been improved from 1991 to 1999, but still continuing higher level. High-Pressure In 1991 photochemical ozone in Mexico City was worst. 4~5m Air Pollutants 224m In 1991, Ozone exceeding 2 points of IMECA value (232 ppb) in 174 days, on the other hand in 1999 it was 3days. 1

2 However in 1991 ozone exceeding 1 points of IMECA value (11ppb) in 353 days and in 1998 and 1999 it was 32days and 3 days respectively. This indicates the extreme values of ozone have been improved, but average ozone levels are still serious situation in Mexico City. Ozone trend in TMA In Tokyo Metropolitan area (TMA : Tokyo metropolis and six surrounding prefectures) photochemical air pollution is still a serious environmental issue since the first incidence was reported in 197. TMA Air pollution trend analysis suggested a change in the mechanism of photochemical ozone formation in summer in TMA. Recently, daily maximum of regional ozone in summer season has been observed outside the central TMA area. Occurrence frequency of daily maximum concentration for photochemical oxidant. This trend of spreading of urban oxidant concentration maxim might be reflecting of increases in NOx emission and decreases in the ratio of the concentrations of VOCs to those of NOx % North Kanto inland area Kansai inland area This indicating an increase in ozone formation potential and decrease in photochemical reactivity. This mechanism was clarified using three dimensional photochemical simulation models Tokyo bay area Oosaka bay area Comparison of Photochemical Air pollution in Mexico City and Tokyo : In 1996 Mexico City Tokyo Emergency level 7 days (19 Jan., 15,29,3,31 Oct., 1,2 Nov.) Maximum O 3 conc. Max O 3 conc. 219ppb (14 Jul) Monthly maximum O 3 concentration at 44 monitering stations in Tokyo ppb (29 Oct.) In 1999 the maximum ozone concentration in Mexico City monitoring stations 1/1 1/31 3/2 4/1 5/1 5/31 6/3 7/3 8/29 9/28 1/28 11/27 12/27 Date AVERAGE MAX MIN 321ppb (15 Oct.) TMA 186ppb (29 Aug.) 2

3 Photochemical simulation was conducted for 29 October October 1999 Comparison between average air pollution s concentrations observed at15 18 monitoring stations and model simulation assuming Mexican emission showed reasonable diurnal variation of ozone. Model comparison of photochemical air pollution formation mechanisms between Tokyo and Mexico City : Comparison study for ozone formation potential due to the topographical difference between Tokyo and Mexico City using PBM(Photochemical Box Model)was conducted. zt Si = U Ri x z z t Model Description PBM(Photochemical Box Model) Wind direction Advective inflow Entrainment of pollutants aloft Chemical Transformation Source Calculation box is fixed Rising mixing -height Photochemical reaction model: CBM- (Carbon Bond Mechanism) by Gary et al. Simplification Classification by the state of carbon-bond (for organic compounds) PAR Single-bond carbon atom TOL(Toluene ETH(Ethylene) XYL(Xylene) OLE(Double-bond carbon atom FORM(Formaldehyde) ISOP(Isoprene) ALD2(Aldehyde group) 33 species 81 reactions Improvement by Dodge Addition of one reaction Air pollution formation potential in Mexico City : Comparison between Tokyo case and Mexico City case based on same Tokyo emission conditions in 1996 In this simulation ozone concentrations were compared between Tokyo case and Mexico City case based on same Tokyo emission conditions. The ozone production potential in Mexico City is approximately 1.25 times higher than Tokyo assuming same emission conditions. In Tokyo case maximum ozone concentration is 12ppb but for Mexico City case maximum ozone concentration is more than 15ppb NO 2 NO O 3 (Mexico City) O 3 (Tokyo)

4 Photochemical simulation on 29 October 1996 Photochemical simulation on 15 October O 3 calc. NO 2 calc. NO calc. O 3 obs. NO 2 obs. NO obs. O3 calc. NO2 calc. NO calc. O3 obs. NO2 obs. NO obs O3 O 3 calc. NO2 2 calc. NO NO calc. O3 O 3 obs. NO2 2 obs. NO NO obs. obs Air flow analysis based on meteorological observations in Mexico City : Vertical and horizontal wind distributions are important meteorological factor in controlling the three dimensional behavior of photochemical air pollution in the valley of Mexico. However information is not enough for the meteorological analysis. Especially no data available for nighttime airflow patterns in Mexico City and surrounding areas. To clarify this an intensive meteorological observation was conducted during three days in April Vertical and horizontal wind distributions were observed at three points in Mexico City. Upper airflow patterns, especially in nighttime, are analyzed. In the nighttime wind speed was very small. During the observational period clockwise wind circulation were observed aloft over the Mexico City area in the early morning time. This three dimensional air flow patterns will be related to photochemical air pollution circulation in Mexico City. Measurements of VOCs in Mexico City and Tokyo : Volatile organic compounds (VOCs) are key pollutants in understanding photochemical air pollution formation mechanisms both in Japan and Mexico. In 1997 co-operative research has been conducted to establish an automatic continuous monitoring system of volatile organic compounds. In February 1998 volatile organic compounds were collected at three points in Mexico City area. Observed data were compared with Tokyo data. Observed VOC data were compared with Tokyo data in HC Mexico Japan Propane Butane Ethane Ethene Acetylene Propane Prope n-butane I-Butane Pe I-Pentane Hexane He Oc Nonane Be Tolue EthylBenzene o-xylene m,p-xylene Tehotihuacan North area DDF(Zocalo) CENICA Urawa(Summer) Urawa(W inter) Niijima(Su m 4

5 C3 (Cenica Cenica) C4 (Urawa( Urawa) Relationship between C3 and C4 (summer) CENICA Urawa C4 (Cenica( Cenica) 5 C3 (Urawa Urawa) C3/C4(Cenica Cenica,Aug.) C3/C4(Urawa Urawa,Aug.) Linear (Urawa( Urawa,Aug.) Linear (Cenica( Cenica,Aug.) y = x R 2 =.9859 y = x R 2 =.345 C3 (Cenica) CENICA Relationship between C3 and C4 C4 (Urawa) 1 15 Mar Aug. Aug. Urawa C4 (Cenica) C3 (Urawa) C3/C4(Cenica,Mar.) C3/C4(Cenica,Aug.) C3/C4(Urawa,Aug.) Linear (Urawa,Aug.) Linear (Cenica,Mar.) Linear (Cenica,Aug.) y = 3.147x R 2 =.9888 y = x R 2 =.9859 y = x R 2 =.345 Benzene (CENICA) Relationship between Toluene and Benzene Toluene (URAWA) Toluene (CENICA) 15 2 Ben./Tol Tol.(.(Cenica,Aug. 2.5 Ben./Tol Tol.(.(Urawa,Aug.) 2 1 Benzene (URAWA) Linear (Urawa( Urawa,Aug.) Linear (Cenica( Cenica,Aug.) y =.84x R 2 =.6912 y =.293x R 2 =.119 Analysis showed extremely high concentration for low carbon number compounds ; Ethane, Ethylene, Acetylene, Propane, Propylene i-butane and n-butane, in Mexico City ranging 1 times of Tokyo data. On the other hand Benzene and Toluene were 2 times higher in comparing with Tokyo data. These differences should be reflecting the difference of emissions of VOCs in Tokyo and Mexico City. Emission survey and further systematic ambient monitoring of VOCs will be conducted to clarify the role and weights in controlling ozone formation both in Tokyo and Mexico City. Further research prospects : To clarify the role and weights of meteorology and emissions of NOx and VOCs in controlling ozone formation both in Tokyo and Mexico City, following studies have been conducting co-operatively. 1. Air pollution trend analysis. To establish the analytical method to clarify the air pollution trends excluding the annual variation of meteorological effects will be essential in order to understand the relationship between emission control and air pollution concentration in the urban atmosphere. Photochemical simulation on 29 October Comparison between 1996 and 1999 O3 Ocalc. 3 calc. NO2 NO calc. 2 calc. NO NO calc. calc. O3 Oobs. 3 obs. NO2 NOobs. 2 obs. NO NO obs. obs. Photochemical simulation on 15 October O3 O 3 calc. NO2 2 calc. NO NO calc. calc. O3 O 3 obs. NO2 obs. 2 obs. NO NO obs. obs. 5

6 2.Vertical measurements of meteorological parameters and ozone concentration. Vertical meteorological parameters such as wind speed, wind direction, temperature, humidity and vertical ozone distribution are essential information in understanding the photochemical air pollution formation mechanisms. For this purpose a series of upper air observation using pilot balloon system and tether sonde system using Kytoon (Kite+balloon) have been conducting in Mexico City. 3. VOCs measurement using continuous measurement system. VOCs are key pollutants to understand the photochemical air pollution formation mechanisms both in Japan and Mexico City. Continuous VOCs measurement has been conducting using an automated monitor. These data will be analyzed with air pollution monitoring data. The collaborative research will be continued. JICA and NIES CENICA and UAM Thank you very much for your attention!! TMA Mexico City Mexico Basic formulation : Due to these topographical and meteorological characteristics average wind speed is weak and air ventilation is small. Due to these topographical and meteorological conditions photochemical air pollution is serious in Mexico City and surrounding areas. zt = U + x Si + + Ri z z t In Tokyo Metropolitan area (TMA : Tokyo metropolis and six surrounding prefectures) photochemical air pollution is still a serious environmental issue since the first incidence was reported in 197. Air pollution trend analysis suggested a change in the mechanism of photochemical ozone formation in summer in TMA. U Average wind speed (m/s) C i Component concentration z t Mixing-height (m) S i Source Chemical Reaction R i 6

7 Comparison between CENICA and URAWA Comparison between CENICA and URAWA C3(Cenica) Benzene(Uraw Benzene(Cenica) C3(Urawa) C3/Ben.(Cenica.Mar.) C3/Ben.(Cenica,Aug.) C3/Ben.(Urawa,Aug.) Linear (Cenica,Aug.) Linear (Cenica,M ar.) Linear (U rawa,aug.) y = x R 2 =.329 y = x R 2 =.4487 y = x R 2 =.38 C3 (Cenica) C4 (Urawa) C4 (Cenica) C3 (Urawa) C3/C4(Cenica,Mar.) C3/C4(Cenica,Aug.) C3/C4(Urawa,Aug.) Linear (Urawa,Aug.) Linear (Cenica,M ar.) Linear (Cenica,Aug.) y = 3.147x R 2 =.9888 y = x R 2 =.9859 y = x R 2 =.345 7