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Health effects
from air pollution come about due to a combination of the concentration
of the air pollutants and the amount of time you are exposed to the
air pollution. Brief exposure to moderately high pollution levels
will normally not lead to any significant problem. For most of us,
therefore, the general API is more relevant as it represents the air
pollution that we shall be exposed to for most of the time. For the
Roadside API, although it is naturally higher on a given day due to
the close proximity to vehicle emission sources, it is less relevant
as we often spend only quite short periods of the day in busy streets
and roads. It will be of more interest to those who spend several
hours each day close to busy roads.
The suggested
precautionary actions are summarised below:
| Air
Pollution Level |
API |
Advice
to Public |
| General
API |
Roadside
API |
| Severe |
aa
aa
aa
aa
aa
aa |
201-500 |
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 |
aa
aa
aa
aa
aa
aa |
101-200 |
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 |
aa
aa
aa
aa
aa
aa |
51-100 |
No
immediate response action is suggested --
Long-term effects may, however, be observed if exposed at this
level persistently for months or years |
| Medium |
aa
aa
aa
aa
aa
aa |
26-50 |
No
response action is required. |
| Low |
aa
aa
aa
aa
aa
aa |
0-25 |
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!
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