XN000022-1993-05-12 — Page 9

APRIL AIR QUALITY REPORT RELEASED

WEDNESDAY, MAY 12, 1993

THE ENVIRONMENTAL PROTECTION DEPARTMENT TODAY RELEASED AIR QUALITY INFORMATION FOR APRIL.

A SPOKESMAN FOR THE ANNOUNCEMENT WAS TO KEEP THE LEVELS IN THE TERRITORY AND TO

(WEDNESDAY)

DEPARTMENT SAID THE PURPOSE PUBLIC INFORMED OF THE AIR EXPLAIN THE MEASUREMENTS.

OF QUALITY

THE

THE ANNOUNCEMENT NORMALLY CONTAINS MONITORING RESULTS OBTAINED AT ITS MONG KOK, CENTRAL/WESTERN AND KWAI CHUNG MONITORING STATIONS.

THESE LOCATIONS ARE TYPICAL OF THREE OF THE IMPORTANT LAND USB TYPES FOUND IN THE TERRITORY, NAMELY:

*

*

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LOCATIONS CLOSE TO ROAD TRAFFIC IN BUILT-UP URBAN DISTRICTS; COMBINED COMMERCIAL AND RESIDENTIAL DISTRICTS; AND DISTRICTS CLOSE TO INDUSTRIAL AREAS.

THE REPORTED AIR POLLUTANTS INCLUDE NITROGEN DIOXIDE (NO2), RESPIRABLE SUSPENDED TOTAL SUSPENDED PARTICULATES (TSP). THE MONITORED CONTINUOUSLY WHILE PARTICLE SAMPLES HOURS, ONCE EVERY SIX DAYS.

SULPHUR DIOXIDE (SO2), PARTICULATES (RSP) AND GASEOUS POLLUTANTS ARE ARE COLLECTED FOR 24

IN APRIL THERE WERE NO EXCEEDANCES OF THE 24-HOUR AIR QUALITY OBJECTIVES FOR ANY OF THE POLLUTANTS REPORTED, EVEN THOUGH THERE WERE DAYS WITH LOW WIND SPEEDS, NORMALLY THE CONDITIONS THAT ALLOW POLLUTANT CONCENTRATIONS TO INCREASE.

DUST LEVELS WERE MUCH LOWER THAN LAST YEAR.

THIS IS THOUGHT TO BE BECAUSE LAST YEAR THERE WAS A DUST EPISODE OF SEVERAL DAYS THAT BROUGHT IN LARGE AMOUNTS OF DUST, AND ALSO BECAUSE THIS YEAR THE RELATIVE HUMIDITY WAS HIGHER.

EVEN SO, CONCENTRATIONS OF TSP AT MONG KOK WERE A SIGNIFICANT PROPORTION OF THE 24-HOUR AIR QUALITY OBJECTIVE.

CONCENTRATIONS OF

THE

SMALLER

RESPIRABLE

SUSPENDED

PARTICULATES WERE SIMILAR AT ALL THREE SITES.

CONCENTRATIONS OF THE GASEOUS SPECIES AT CENTRAL/WESTERN AND KWAI CHUNG FOLLOWED SIMILAR TRENDS ΤΟ EACH OTHER INDICATING THAT METEOROLOGY WAS THE DRIVING FORCE FOR THE OBSERVED LEVELS.

THE PEAK ON THE 21ST AND 22ND OF THE MONTH WAS ASSOCIATED WITH LIGHT WINDS THAT WERE DRIER THAN AVERAGE.

THE FOUR POLLUTANT'S DISCUSSED HAVE DIFFERENT ORIGINS. 502 MOSTLY ORIGINATES FROM THE COMBUSTION OF SULPHUR CONTAINING FOSSIL FUELS. NO2 IS FORMED EITHER DIRECTLY DURING COMBUSTION OR, BY THE ATMOSPHERIC OXIDATION OF NITRIC OXIDE (NO) WHICH IS ALSO PRODUCED DURING COMBUSTION.

/VEHICLE EXHAUST

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