XN000022-1993-09-14 — Page 18

17

TUESDAY, SEPTEMBER 14, 1993

AT THE BEGINNING OF THE AIR POLLUTION EPISODE, THE TOOK IMMEDIATE ACTION TO ACQUIRE ADDITIONAL PARTICULATE SOME SELECTED STATIONS.

DEPARTMENT

SAMPLES

AT

ASSOCIATED WITH THE EPISODE, THERE WERE EXCEEDANCES OF DAILY NO2 OBJECTIVE OF 150 UG PER CUBIC METER AT MONG KOK AND LIMIT OF 260 UG PER CUBIC METER AT KWAI CHUNG ON AUGUST 25,

AT

THE

TSP

MONG KOK, A DAILY NITROGEN DIOXIDE CONCENTRATION OF 154 UG PER CUBIC METER WAS RECORDED, WHICH WAS SLIGHTLY ABOVE THE 24-HOUR OBJECTIVE WHILE THE LEVELS AT CENTRAL/WESTERN WERE CLOSE TO THE OBJECTIVE VALUE.

NO OBSERVATION OF NO2 WAS AVAILABLE AT KWAI CHUNG. THE ADDITIONAL PARTICULATE SAMPLE AT KWAI CHUNG ON THAT DAY REVEALED THAT TSP LEVELS EXCEEDED THE DAILY LIMIT BY 23 PER CENT AND RSP VALUES APPROACHED THE OBJECTIVE VALUE.

THE FOUR POLLUTANTS DISCUSSED HAVE DIFFERENT ORIGINS. 802 MOSTLY ORIGINATES FROM THE COMBUSTION OF SULPHUR CONTAINING FOSSIL FUELS.

NO2 IS

OR,

BY THE PRODUCED

FORMED EITHER DIRECTLY DURING COMBUSTION ATMOSPHERIC OXIDATION OF NITRIC OXIDE (NO) WHICH IS ALSO DURING COMBUSTION.

VEHICLE EXHAUST IS A MAJOR SOURCE OF NO AND NO2. IT IS ALSO A MAJOR SOURCE OF AIRBORNE PARTICLES, OTHER SOURCES INCLUDE INDUSTRY, FURNACES AND BOILERS, CONSTRUCTION ACTIVITIES, THE SEA AND SOIL DUST.

SHORT-TERM

THE DEPARTMENT CURRENTLY MONITORS AIR QUALITY CONTINUOUSLY AT 11 STATIONS, INCLUDING THE THREE MENTIONED ABOVE. MEASUREMENT CAMPAIGNS ARE ALSO UNDERTAKEN AS AND WHERE THE NEED ARISES.

NOTE TO EDITORS:

FURTHER ENQUIRIES CAN BE DIRECTED TO PRINCIPAL ENVIRONMENTAL PROTECTION OFFICER, MR RAYMOND LEUNG ON TELEPHONE 594 6401.

0

—

/18