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Press Release

State of Air Pollution in FY 2002

September 10, 2003

Prefectures and the ordinance-designated cities monitor air pollution at 2,134 monitoring stations throughout Japan in accordance with the Air Pollution Control Law. The monitoring stations numbered 1,704 ambient air pollution monitoring stations*1 (APMSs) and 430 roadside air pollution monitoring stations*2 (RAPMSs) as of the end of FY 2002.

Based on the monitoring result, the Ministry of the Environment will step up efforts to implement comprehensive measures, including emission control from factories, business establishments and motor vehicles and dissemination of low-emission vehicles, to improve the atmospheric environment.

1. Nitrogen Dioxide (NO2)

The achievement rate of the environmental quality standard (EQS) for NO2 is 99.1% for APMSs and 83.5% for RAPMSs. Compared to FY 2001 results of 99.0% for APMSs and 79.4% for RAPMSs, the achievement rate at RAPMSs has shown a slight improvement. Changes in the annual averages of NO2 at RAPMSs show a gradually improving trend in recent years. (Figs. 1-1, 1-2 and 1-3)

2. Suspended Particulate Matter (SPM)

The achievement rate of EQS for SPM is 52.6% for APMSs and 34.3% for RAPMSs. Compared to FY 2001 results of 66.6% for APMSs and 47.0% for RAPMSs, the rates have declined. On the other hand, changes in the annual averages of SPM show a gradually improving trend in recent years. (Figs. 2-1, 2-2 and 2-3)

3. Photochemical Oxidant (Ox)

The achievement rate of EQS for Ox is still very low at only 0.5% for the APMSs and RAPMSs combined. (Fig. 3)

4. Sulfur Dioxide (SO2)

The EQS for SO2 was achieved at 99.8% of the APMSs and 99.0% of the RAPMSs. Almost all monitoring stations have achieved EQS in recent years. (Figs. 4-1, 4-2 and 4-3)

5. Carbon Monoxide (CO)

All monitoring stations have achieved EQS for CO. (Fig. 5)

The Ministry of the Environment provides real-time information on the state of air pollution through the Internet and cell phones, using the Atmospheric Environmental Regional Observation System (AEROS).

Notes: 1. Ambient air pollution monitoring stations monitor air pollution of the general atmospheric environment on a constant basis.
2. Roadside air pollution monitoring stations, set up at intersections and roadsides, monitor air pollution caused by substances emitted from automobiles on a constant basis.
3. Environmental quality standards for air pollution were established for benzene, trichloroethylene and tetrachloroethylene on February 4, 1997, for dioxins on December 27, 1999 and for dichloromethane on April 20, 2001. The states of air pollution involving these substances are put together separately.

<Reference> Environmental Quality Standards and Methods of Assessment

1. Environmental Quality Standards

Substance Environmental condition
Nitrogen dioxide The daily average for hourly values shall be within the 0.04-0.06 ppm zone or below that zone.
Suspended particulate matter The daily average for hourly values shall not exceed 0.10 mg/m3, and hourly values shall not exceed 0.20 mg/m3.
Photochemical oxidant Hourly values shall not exceed 0.06 ppm.
Sulfur dioxide The daily average for hourly values shall not exceed 0.04 ppm, and hourly values shall not exceed 0.1 ppm.
Carbon monoxide The daily average for hourly values shall not exceed 10 ppm, and average of hourly values for any consecutive eight hour period shall not exceed 20ppm.
Notes: 1. Suspended particulate matter is defined as airborne particles with a diameter smaller than or equal to 10 Ám.
2. Photochemical oxidants are oxidizing substances such as ozone and peroxiacetyl nitrate produced by photochemical reactions (only those capable of isolating iodine from neutral potassium iodide , excluding nitrogen dioxide.).

2. Methods of Assessment

(1) Short-term assessment (excluding nitrogen dioxide)

Assessment is carried out by comparing the daily average of the hourly values on the day when the measurement is taken, or the average of eight-hour values, or the value of each hour to the environmental quality standard.

(2) Long-term assessment

A. Nitrogen dioxide

Assessment is carried out by comparing the 98% value from the low end (98% percentile of daily averages in a year) of daily averages measured over a period of one year to the environmental quality standard.

B. Suspended particulate matter, sulfur dioxide, and carbon monoxide

Assessment is carried out by comparing the highest value of daily averages measured over a period of one year - excluding the top 2% of measured values (annual daily averages excluding the top 2%)-to the environmental quality standard.
However, regardless of the above-mentioned assessment method, the environmental quality standards are deemed unachieved if there are two consecutive days in which the daily averages exceed the environmental quality standard.

3.    Effects of the various substances subject to environmental quality standards on human health and the environment

(i) Nitrogen dioxide
Besides the fact that nitrogen dioxide in high concentrations will affect the respiratory organs, it is said to be the causal substance of acid rain and photochemical oxidants.
(ii) Suspended particulate matter
Because it remains in the air for a long time, exposure to high concentrations will lead to deposition in the lungs and bronchus, thus affecting the respiratory organs.
(iii) Photochemical oxidant
The cause of the so-called "photochemical smog." High concentrations will not only irritate mucous membranes and affect the respiratory organs but also affect plants, including agricultural crops.
(iv) Sulfur dioxide
Sulfur dioxide at high concentrations will not only affect the respiratory organs but it is also the causal substance of acid rain, which affects forests, lakes, reservoirs, etc.
(v) Carbon monoxide
Carbon monoxide will couple with hemoglobin in the blood, impeding the function of oxygen transportation. It is known to lengthen the life span of methane in the air, which is one of the greenhouse gases.


[LINK]
* Change in Annual Average of Nitrogen Dioxide (NO2) Concentration
* Achievement of the Environmental Quality Standard for Nitrogen Dioxide (NO2)
* Achievement of the Environmental Quality Standard for Nitrogen Dioxide (NO2)
* Change in Annual Average of Suspended Particulate Matter (SPM) Concentration
* Achievement of the Environmental Quality Standard for Suspended Particulate Matter (SPM) (ambient air pollution monitoring stations)
* Achievement of the Environmental Quality Standard for Suspended Particulate Matter (SPM) (roadside air pollution monitoring stations)
* Number of Monitoring Stations (APMSs+RAPMSs) by Photochemical Oxidant Levels
* Change in Annual Average of Sulfur Dioxide (SO2) Concentration
* Achievement of the Environmental Quality Standard for Sulfur Dioxide (SO2) (ambient air pollution monitoring stations)
* Achievement of the Environmental Quality Standard for Sulfur Dioxide (SO2) (roadside air pollution monitoring stations)
* Change in Annual Average of Carbon Monoxide (CO) Concentration

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