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Particulate matter (PM) 懸浮粒子

Particulate matter represents a complex mixture of small particles and liquid droplets suspended in the air. Major sources of particulate matter include construction activities, road dust re-suspension and combustion.

Particulate matter with aerodynamic diameter smaller than 10 micrometres (μm) (PM10) is already small enough to pass through nose and respiratory tract and enter our lungs. Chronic exposure to particulate matter increases the risk of cardiovascular and respiratory diseases, or even lung cancer. Those particulate matter smaller than 2.5 μm (PM2.5), also known as fine suspended particles, is especially harmful. It is one of the most important parameters for air pollution monitoring.

In Hong Kong, Air Quality Health Index (AQHI) was introduced to replace the late Air Pollution Index in December 2013 from Environmental Protection Department, HKSAR. Individuals with lung and heart disease, influenza, asthma, elderly people and children are sensitive to PM. They are advised to reduce physical exertion and outdoor activities and avoid prolonged stay in areas with heavy traffic when AQHI is at high health risk category or higher.

懸浮粒子包括懸浮於空氣中的固體粒子和小水點等複雜混合物,多來自建築活動、道路上揚起的灰塵及燃燒燃料。

氣動力學直徑小於十微米的顆粒物可以經鼻腔及呼吸道進入肺部,長期暴露於此類可吸入顆粒物會增加患上心血管病、呼吸系統疾病甚至肺癌等風險。 其中小於2.5微米的懸浮粒子,亦稱微細懸浮粒子,尤其有害。它是衡量空氣污染指標的其一重要成份。

香港政府環境保護署於2013年12月以空氣質素健康指數代替舊有的空氣污染指數。心肺疾病、感冒或哮喘患者與及長者和小童都可能對可吸入顆粒物特別敏感,當空氣質素健康指數健康風險級別為高或以上水平時 ,他們都應減少體力消秏及戶外活動,亦應避免長時間在交通繁忙的街道上逗留以減少顆粒物的吸入數量。

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