[转]读懂美国大使馆发布的空气质量指数

原文连接：http://sunote.info/tag/beijingair/

从2月9日开始，@BeijingAir修改了报告的内容，从原来的报告过去1小时和当天平均值改为PM2.5和Ozone两个值。

原来的格式为：

2-9-2010 ; 11:00 ; Latest Hour ; 0.091 ; 169 ; Unhealthy ; Today’s Avg ; 0.216 ; 266 ; Very Unhealthy

现在的格式为：

02-21-2010; 09:00; PM2.5; 189.0; 239; Very Unhealthy // Ozone; 0.9; 1; Good

@BeijingAir是美驻华使馆在使馆区设置的一个空气检测站，将数据每隔一小时自动发送到twitter上。以前的数值仅仅为PM2.5，2月9日之后增加了Ozone。

几种污染物

PM2.5是Particulate matter 2.5的缩写，指大气中直径小于或等于2.5微米的颗粒物，也称为可入肺颗粒物。会进入肺部的气体交换区（肺泡），引起血管炎和动脉粥样硬化，进而导致心脏病和其他循环系统疾病。

PM10指直径等于或小于10微米，可以进入人的呼吸系统的颗粒物，也称为可吸入颗粒物。10微米到2.5微米的颗粒，部分会被肺呼出，部分被支气管和肺部组织吸附。

PM100指直径小于和等于100微米的颗粒物，也称总悬浮颗粒物。大于10微米的大多数被鼻腔和咽喉阻挡，不会造成麻烦。

PM2.5的影响

大气中PM-2.5污染控制的意义与途径一文中提到：

PM-2.5是导致城市人为能见度下降的祸首
PM-2.5是城市大气污染物中损害人体健康的元凶

什么是Ozone

Ozone是我们呼吸的空气，对人体健康有直接地影响。

解读@BeijingAir数据

目前@BeijingAir的数据格式为：

日期; 时间; PM2.5; PM2.5浓度; PM2.5空气质量指数; 健康等级 // Ozone; Ozone浓度; Ozone指数; Ozone健康等级

PM2.5的空气质量指数

Air Quality Index Levels of Health Concern	Numerical Value	Meaning
Good	0 to 50	Air quality is considered satisfactory, and air pollution poses little or no risk
Moderate	51 to 100	Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
Unhealthy for Sensitive Groups	101 to 150	Members of sensitive groups may experience health effects. The general public is not likely to be affected.
Unhealthy	151 to 200	Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
Very Unhealthy	201 to 300	Health alert: everyone may experience more serious health effects
Hazardous	301 to 500	Health warnings of emergency conditions. The entire population is more likely to be affected.

(来源)

Ozone指数

Air Quality Index	Protect Your Health
Good (0-50)	No health impacts are expected when air quality is in this range.
Moderate (51-100)	Unusually sensitive people should consider limiting prolonged outdoor exertion.
Unhealthy for Sensitive Groups (101-150)	The following groups should limit prolonged outdoor exertion: People with lung disease, such as asthma Children and older adults People who are active outdoors
Unhealthy (151-200)	The following groups should avoid prolonged outdoor exertion: People with lung disease, such as asthma Children and older adults People who are active outdoors Everyone else should limit prolonged outdoor exertion.
Very Unhealthy (201-300)	The following groups should avoid all outdoor exertion: People with lung disease, such as asthma Children and older adults People who are active outdoors Everyone else should limit outdoor exertion.

(来源)