11
TUESDAY, SEPTEMBER 13, 1994
AIR QUALITY IN AUGUST WAS AFFECTED BY A VARIETY OF NATURAL MAN-MADE FACTORS.
AND
RECORDED AT THE LOW WIND SPEEDS ON THAT DAY POLLUTANTS. WHAT LITTLE
HIGHER CONCENTRATIONS OF ALL POLLUTANTS WERE THREE LOCATIONS ON AUGUST 3 BECAUSE PREVENTED THE DISPERSION OF LOCALLY EMITTED WIND THERE WAS, WIND FROM THE NORTH BROUGHT WITH IT CONTINENTAL AIR.
TSP LEVELS AT MONG KOK,
EXCEEDED THE OBJECTIVE VALUE OF 260 MICROGRAMMES PER CUBIC METRE.
AIR 24-HOUR
QUALITY
HEAVY RAIN OVER THE NEXT FEW DAYS KEPT MOST ESPECIALLY SULPHUR DIOXIDE, LOW.
POLLUTANT
LEVELS,
BETWEEN AUGUST 17 AND 23, AIR QUALITY WAS AFFECTED BY RAST CYCLONE FRED
FROM THE NORTHWESTWARDS WHICH MOVED PHILIPPINES, ACROSS THE SOUTH CHINA SEA, AND INTO CHINA.
OF
TROPICAL THE
CONDITIONS OVER
THE DESCENDING AIR FROM FRED MADE ATMOSPHERIC HONG KONG VERY STABLE. THIS LIMITED THE UPWARD MOVEMENT OF POLLUTANTS WHILE LOW SURFACE WIND SPEEDS AGAIN PREVENTED HORIZONTAL DISPERSION.
LOCALLY EMITTED AIR POLLUTANTS WERE THEREFORE TRAPPED AND CONCENTRATIONS WERK OBSERVED FOR THAT PERIOD.
HIGH
THERE WAS HEAVY RAIN BETWEEN AUGUST 26 AND 29. MEANWHILE,
TOGETHER WITH THE POOR PUBLIC HOLIDAYS FROM AUGUST 27 TO 29, CONDITIONS, ALSO REDUCED HUMAN ACTIVITY.
THE
WEATHER
THESE FACTORS HELPED TO KEEP DOWN AIR POLLUTION THOSE FEW DAYS.
LEVELS
DURING
GASES THE
AND PARTICLES DESCRIBED ORIGINATE
FROM VARIOUS
SULPHUR PRODUCED WHEN FUELS THAT CONTAIN
ARE SOURCES. SO2 IS MOSTLY BURNED. NO2 IS FORMED DURING COMBUSTION BY THE COMBINATION OF NITROGEN AND OXYGEN.
HOWEVER THE MAJORITY OF IT IS FORMED IN THE ATMOSPHERE OXIDATION OF NITRIC OXIDE (NO), ALSO A PRODUCT OF COMBUSTION.
BY THE
TERMS
VEHICLE EXHAUST IS AN IMPORTANT SOURCE OF NO AND NO2 IN OF IMPACT ON LOCAL AIR QUALITY. IT IS ALSO A MAJOR SOURCE OF AIRBORNE PARTICULATE MATTER, ESPECIALLY THE SMALLER RESPIRABLE PARTICLES.
DIESEL-ENGINED VEHICLES SUCH AS TAXIS, PUBLIC PASSENGER COACHES, FRANCHISED BUSES AND LIGHT AND VEHICLES ARE THE GREATEST CONTRIBUTORS.
OTHER SOURCES OF PARTICLES INCLUDE INDUSTRY, BOILERS, CONSTRUCTION ACTIVITIES, THE SEA AND THE SOIL.
LIGHT BUSES, HEAVY GOODS
FURNACES AND
/IT IS