FoE API is temporary unavailable.
| Current API at 01:00 |
|
03 September 2010 |
Weakness of EPD API
Air Pollution Index (API) should be a tool for informing
the public about the state of current air pollution. However,
API released by Environmental Protection Department (EPD)
is only able to tell us the air quality in the last hour,
8 hours or even 12 hours ago. In other words, the index
currently in use, which is vitally important to the public
may have up to 12-hour time lag. It is obvious that API
is failing to inform the public the current air quality
situation.
For example, API used now might report the current pollution
levels as “low” (0-25) or “medium” (26-50) when, in reality,
the level may has already deteriorated to “very high” (100
or above). This would be life threatening to those who are
suffering from heart or respiratory diseases because they
do not have accurate information. If a person with heart
disease read the time-lagged index and decided to engage
in outdoor activities, the threat to their health could
be serious. Conversely, in the moment of good air quality,
people with such disease might change their schedule or
even cancel events unnecessarily because the index is telling
them the air quality is bad.
The sudden change of air quality is not unusual in Hong
Kong. It is a common phenomenon in winter when there is
prevalent northerly wind and the government should be fully
aware of this situation.
Take the Nike Hong Kong 10K challenge 2006, which was
hosted on November 19th 2006, as an example. EPD reported
API as 61 at 1pm on that day, but the index was not reflecting
the latest air quality, which in fact, the air quality at
the moment was the worst on that day. Three pollutants -
sulphur dioxide (SO2), repirable suspended particulates
(RPS) and nitrogen dioxide (NOX), were reported at a high
level of concentration. It would be dangerous to a person
with heart attack to engage in outdoor activities if he
had read API at that time.
What's new of Current API
API is a calculation of respirable suspended particulate
(RSP), sulphur dioxide (SO2), carbon monoxide (CO), ozone
(O3) and nitrogen dioxide (NO2) concentrations measured
by the EPD in different monitoring stations. RSP is a key
pollutant which dominates about 70% of air pollution, however,
unlike the other pollutants, EPD does not provide any data
on the hourly concentration level of RSP. In fact, RSP is
only reported on a 24-Hour basis, in case RPS is recorded
high levels at a particular moment, API does not show this
currently.
Friends of the Earth (HK) launch the Current API (CAPI)
that would reflect the last hour of air quality. With the
assistance of the CAPI, the public would be able to access
current data about the air quality, which would reduce the
threat of exposure on days of poor air quality.
Current API
FoE API is temporary unavailable.
- : no update data is provided from EPD.
Source: http://www.epd-asg.gov.hk/eindex.php
FoE (HK)'s appeal
In early June
2006, the Council of Sustainable Development suggested that
on days with 'highly polluted air', an alarm system with
a ‘forecast ability’ should be implemented to advise the
public. However, as stated before, the existing API has
a time lag that cannot show the current air quality; hence,
this alarm system will not be able to produce an accurate
“forecast”. If the government wants to set up an alarm system,
the ‘time lag’ problem has to be resolved. .
Also, the API is only a tool to show the air quality. To protect the health of the general public, the government must:
Face the problem of air pollution by putting more concern
for the environment, energy saving and public health in
energy policies. Right now, the maintenance of a stable
supply of electricity is the most important criterion
of the whole policy.
Figure out a way to clean the air, and at the same time
have better town planning to avoid heat island and wall
effects (windshielding effect).
__Coordinate better with
the Mainland in order to resolve cross-boundary air pollution
issue.
What can I do to tackle the problem?
To reduce air pollution, there are a lot of things we can do as the general public:
Save energy by not overusing your air conditioner and
remembering to turn the power off when finished using
an electric appliance. Purchase the appliance with high
energy efficiency.
Come and join FoE’s Power
Smart Contest.;
Drive less, ride more.
Have more plants at home.
Avoid using aerosol products (e.g. hair spray,
air freshener, deodorant, insecticides etc.) to reduce
the production of volatile organic compounds.
Avoid non-essential shopping to reduce energy waste.
These are just a few easy things we can do to save money
and, at the same time, helping the environment. Other examples
are shown on our website.
Potential health effects for different API
|
Air Quality Status
|
Air Pollution Level
|
API
|
Health Implications[1]
|
| Air quality significantly worse
than both short-term and long-term AQOs |
Severe
|
201
to 500
|
People with existing heart or respiratory illnesses may experience significant aggravation of their symptoms and there will be also widespread symptoms in the healthy population. These include eye irritation, wheezing, coughing, phlegm and sore throat.
|
|
Air quality worse than both short-term and long-term AQOs
|
Very High
|
101 to 200
|
People with existing heart or respiratory illnesses may notice mild aggravation of their health conditions. Generally healthy individuals may also notice some discomfort.
|
| Air quality within the short-term
AQOs but worse than the long-term |
High
|
51 to 100
|
Very few people, if any, may notice
immediate health effects. Long-term effects may, however,
be observed if you are exposed to such levels for a
long time. |
| Air quality within all AQOs |
Medium
|
26 to 50
|
None expected for the general population. |
|
Air quality well within all AQOs
|
Low
|
0 to 25
|
None expected. |
[1]
The health implications set out above serve as a broad guide
only as a gradual increasing risk of effects is expected
as pollutant concentrations rise. Source: EPD
Advise to the public
The suggested precautionary actions are summarised below:
|
Air Pollution Level
|
API
|
Advice to Public
|
|
General API
|
Roadside API
|
|
Severe
|
|
201 to 500 |
The general public are advised
to reduce physical exertion and outdoor activities |
The general public are advised
to avoid prolonged stay in areas with heavy traffic.
If it is necessary to stay in streets or roads with
heavy traffic, they are advised to reduce physical exertion
as far as possible |
|
Very High
|
|
101 to 200 |
Persons with existing heart or respiratory illnesses
(such as coronary heart and cardiovascular diseases,
asthma, chronic bronchitis and chronic obstructive airways
diseases)are advised to reduce physical exertion and
outdoor activities |
Persons with existing heart or respiratory illnesses
(such as coronary heart and cardiovascular diseases,
asthma, chronic bronchitis and chronic obstructive airways
diseases) are advised to avoid prolonged stay in areas
with heavy traffic. If it is necessary to stay in streets
or roads with heavy traffic, they are advised to reduce
physical exertion as far as possible. |
|
High
|
|
51 to 100 |
No immediate response
action is suggested --Long-term effects may, however,
be observed if exposed at this level persistently for
months or years |
|
Medium
|
|
26 to 50 |
No response action is required
|
|
Low
|
|
0 to 25 |
No response action is required
|
As the health effects on individuals may vary, you should
seek advice from a medical doctor if you are in doubt or
feel uncomfortable. If you are a smoker, you should quit
smoking now!
Source:
EPD:
(http://www.epd-asg.gov.hk/english/advice/advice.php)
Sources of Air Pollutants
|
Air Pollutants
|
Main Sources during 2005
|
Health Implications
|
| Sulphur dioxide (SO2)
|
Electricity generation (91%), ship transport (5%)
|
Respiratory diseases, weaker lungs, higher morbidity and mortality rates
|
|
Industrial, domestic and non-road transport (4%)
|
| Nitrogen dioxide (NO2) |
Electricity generation (50%), road transport
(25%), ship transport (18%), civil aviation (5%)
|
Increase in respiratory allergies and infection,
hindered lung development |
|
Respirable suspended particulates (RSP)
|
Electricity generation (48%), transport (25%), construction (16 %), ship transport (7%)
|
Respiratory diseases, weaker lungs, cancer
|
|
Volatile organic compounds (VOC)
|
Consumer goods, paints, printed matters etc. (81%),
road transport (16%) |
Painful eyes, coughing, reduced ability in sports,
impaired chromosomes |
| Carbon monoxide (CO) |
Road transport (88%), electricity generation (4%), ship transport (3%), civil aviation (3%)
|
Hindered sensory integration, dangerous to pregnant women and patients with cardiovascular diseases
|
Source: EPD (http://www.epd.gov.hk/epd/tc_chi/environmentinhk/air/data/emission_inve.html)
CAPI
Calculation Method
Our setting up of the CAPI is to highlight the time-lag
of the API system. Instead of waiting 8 or 24 hours to calculate
the API, we ask the question, "What would be the API
corresponding to the current concentration of the air pollutants
(if these concentrations were to stay steady over time)?"
To answer this question, all we need to do is to use the
24/8 hour reference levels of the API as the 1-hour reference
levels for CAPI. The calculation of the CAPI is similar
to that of the API *, and the specific
subindex levels and their corresponding concentrations are
as follows:
* EPD http://www.epd.gov.hk/epd/english/environmentinhk/air/air_quality/backgdf_3.html
CAPI Subindex Levels and Their Corresponding Concentrations
CAPI Subindex Level |
Corresponding Concentrations (μg/m3) |
RSP
1-hr |
SO2
1-hr |
NO2
1-hr |
CO
1-hr |
O3
1-hr |
0 |
0 |
0 |
0 |
0 |
0 |
25 |
28 |
40 |
53 |
2500 |
60 |
50 |
55 |
80 |
107 |
5000 |
120 |
100 |
180 |
350 |
200 |
10000 |
240 |
200 |
350 |
800 |
373 |
17000 |
400 |
300 |
420 |
1600 |
753 |
34000 |
800 |
400 |
500 |
2100 |
1000 |
46000 |
1000 |
500 |
600 |
2620 |
1253 |
57000 |
1200 |
We understand that the longer-term (e.g. 24-hr) average
concentrations are often tighter than the shorter term (e.g.
1-hr) averages. For example, the 24-hour average concentrations
for SO2 is approximately half of
that of the corresponding 1-hour averages. However, the
Hong Kong Air Quality Objectives (AQO) are so out-of-date
and loose that we don’t feel such adjustment is necessary
for most of the pollutants. For example, the 24-hour average
concentration recommended by the World Health Organization
(WHO) for RSP and SO2 are 50 and
20 μg/m3, respectively; our use of
180 and 350 μg/m3 as 1-hour average
concentration for RSP and SO2 are
still more than double the corresponding 24-hour
average concentration recommended by WHO for these pollutants.
We find that the only adjustment necessary is for NO2,
where the WHO guideline recommends an 1-hour average concentration
of 200 μg/m3. Hence, the direct use of 150 μg/m3
from EPD's 24-hour average is not warranted, and we have
scaled the 24-hour average concentrations of EPD by a factor
of 4/3 before applying it as the 1-hour average concentrations
of the CAPI as shown in the above table.
Acknowledgement to Professor Alexis Lau, Manager of Environmental
Central Facility of The Hong Kong University of Science
& Technology, for his technical advice.
Enquiry: 2528 5588 FoE website: www.foe.org.hk
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