XN000022-1993-06-11 — Page 23

FRIDAY, JUNE 11, 1993

22

(RSP)

THE REPORTED AIR POLLUTANTS INCLUDE SULPHUR DIOXIDE (802), NITROGEN DIOXIDE (NO2), RESPIRABLE SUSPENDED PARTICULATES

AND

TOTAL SUSPENDED PARTICULATES

(TSP).

THE GASEOUS POLLUTANTS ARE MONITORED CONTINUOUSLY WHILE PARTICLE SAMPLES ARE COLLECTED FOR 24 HOURS, ONCE EVERY SIX DAYS.

IN MAY, THERE WERE DIFFERENCES BETWEEN THE SITES. AT CONCENTRATIONS OF NITROGEN DIOXIDE AND PARTICLES WERE AGAIN HIGHER THE STREET LEVEL SITE IN MONG KOK THAN AT THE OTHER TWO SITES.

CONCENTRATIONS OF SULPHUR DIOXIDE VARIED BETWEEN THE THREE SITES BECAUSE OF THE DIFFERENT SOURCES IN EACH AREA.

AT THE END OF THE MONTH, AROUND MAY 27 TO 29, NITROGEN LEVELS AT ALL THREE SITES INCREASED TO A MAXIMUM FOR THE MONTH.

DIOXIDE

IN MONG KOK, THE LEVELS ROSE TO AN AVERAGE OF 161 UG/CU.M. FOR

QUALITY OBJECTIVE VALUE OF MAY 29, JUST ABOVE THE 24-HOUR AIR

150

UG/CU.M.

DAY EPD ANALYSIS OF THE THREE

PERIOD SHOWS THAT THE SUNNY

POOR

BECAUSE POLLUTANT DISPERSION

OF WEATHER, COMBINED WITH

LOW WINDSPEEDS, PROVIDED SUITABLE CONDITIONS FOR NITRIC OXIDE IN THE AIR TO BE OXIDISED TO NITROGEN DIOXIDE.

THE DRY CONDITIONS DURING THAT PERIOD ALSO ALLOWED DUST LEVELS TO INCREASE AND PRODUCE ELEVATED CONCENTRATIONS AT ALL THREE STATIONS.

IN MONG KOK THE LEVELS WERE CLOSE TO THE 24-HOUR LIMIT

OF 200

UG/CU.M.

IN MONG KOK AND KWAT COMPARED TO 1992,

CHUNG, LEVELS OF S02

AND NO2

TSP LEVELS WERE HIGHER THAN IN THE SAME MONTH. IN MONG KOK, WERE ALSO HIGHER THAN LAST YEAR BUT AT KWAI CHUNG, THEY WERE SIMILAR.

THE FOUR POLLUTANTS DISCUSSED HAVE DIFFERENT ORIGINS.

S02 MOSTLY ORIGINATES FROM THE COMBUSTION OF CONTAINING FOSSIL FUELS. NO2 IS FORMED EITHER DIRECTLY

ATMOSPHERIC OXIDATION OF NITRIC OX IDE COMBUSTION OR, BY THE WHICH IS ALSO PRODUCED DURING COMBUSTION.

SULPHUR DURING (NO)

OF NO AND NO2. VEHICLE PARTICLES; OTHER SOURCES ACTIVITIES, THE

MAJOR SOURCE VEHICLE EXHAUST IS A EXHAUST IS ALSO A MAJOR SOURCE OF AIRBORNE INCLUDE INDUSTRY, FURNACES AND BOILERS, CONSTRUCTION SEA AND SOIL DUST,

THE EPD CURRENTLY

MONITORS AIR

11

QUALITY CONTINUOUSLY AT

MEASUREMENT STATIONS, INCLUDING THE THREE MENTIONED ABOVE, SHORT-TERM CAMPAIGNS ARE ALSO UNDERTAKEN AS AND WHERE THE NEED ARISES.

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