Air Quality Index Scale and Color Legend

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The table below defines the Air Quality Index scale as defined by the US-EPA 2016 standard:

AQI Air Pollution Level Health Implications Cautionary Statement (for PM2.5)
0 - 50 Good Air quality is considered satisfactory, and air pollution poses little or no risk None
51 -100 Moderate 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. Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
101-150 Unhealthy for Sensitive Groups Members of sensitive groups may experience health effects. The general public is not likely to be affected. Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
151-200 Unhealthy Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion
201-300 Very Unhealthy Health warnings of emergency conditions. The entire population is more likely to be affected. Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.
300+ Hazardous Health alert: everyone may experience more serious health effects Everyone should avoid all outdoor exertion

For more information about the pollutants included in the AQI scale, please refer to:

For more information about AQI scales from other countries, please refer to:

Advisories

The following advisories, from the Singapore Ministry of Health (MOE), give a very good explanation, in many languages of the health advisories for the different AQI ranges (PSI=AQI).

AQI Calculator



Select a pollutant:
PM2.5 Particulate <2.5 microns
PM10 Particulate <10 microns
O3 Ozone (1hr avg)
O3 Ozone (8 hours average)
SO2 Sulfur Dioxide (1 hour average)
SO2 Sulfur Dioxide (24 hours average)
NO2 Nitrogen Dioxide
CO Carbon Monoxide

Select the pollutant for which you want to convert the concentration into AQI.



PM2.5 AQI scale: Concentration to AQI
AQI:
0..50
50..100
100..150
150..200
200..300
300..400
400..500
Conc.01235.555.5150.5250.5350.5500.5

The above calculator is based on the work from the US EPA Air Now calculator, available at:

airnow.gov

US EPA AQI conversion table

PM2.5 AQI conversion table - (concentration: AQI value)
0: 0
20: 67
40: 111
60: 152
80: 163
100: 173
120: 184
140: 194
160: 210
180: 230
1: 4
21: 69
41: 114
61: 153
81: 163
101: 174
121: 184
141: 195
161: 211
181: 231
2: 8
22: 71
42: 116
62: 153
82: 164
102: 174
122: 185
142: 196
162: 212
182: 232
3: 13
23: 73
43: 119
63: 154
83: 164
103: 175
123: 186
143: 196
163: 213
183: 233
4: 17
24: 76
44: 121
64: 154
84: 165
104: 176
124: 186
144: 197
164: 214
184: 234
5: 21
25: 78
45: 124
65: 155
85: 166
105: 176
125: 187
145: 197
165: 215
185: 235
6: 25
26: 80
46: 126
66: 156
86: 166
106: 177
126: 187
146: 198
166: 216
186: 236
7: 29
27: 82
47: 129
67: 156
87: 167
107: 177
127: 188
147: 198
167: 217
187: 237
8: 33
28: 84
48: 131
68: 157
88: 167
108: 178
128: 188
148: 199
168: 218
188: 238
9: 38
29: 86
49: 134
69: 157
89: 168
109: 178
129: 189
149: 199
169: 219
189: 239
10: 42
30: 88
50: 136
70: 158
90: 168
110: 179
130: 189
150: 200
170: 220
190: 240
11: 46
31: 90
51: 139
71: 158
91: 169
111: 179
131: 190
151: 201
171: 221
191: 241
12: 50
32: 93
52: 141
72: 159
92: 169
112: 180
132: 190
152: 202
172: 222
192: 242
13: 52
33: 95
53: 144
73: 159
93: 170
113: 180
133: 191
153: 203
173: 223
193: 243
14: 54
34: 97
54: 146
74: 160
94: 170
114: 181
134: 191
154: 204
174: 224
194: 244
15: 56
35: 99
55: 149
75: 160
95: 171
115: 181
135: 192
155: 205
175: 225
195: 245
16: 59
36: 101
56: 150
76: 161
96: 171
116: 182
136: 192
156: 206
176: 226
196: 246
17: 61
37: 104
57: 151
77: 161
97: 172
117: 182
137: 193
157: 207
177: 227
197: 247
18: 63
38: 106
58: 151
78: 162
98: 172
118: 183
138: 193
158: 208
178: 228
198: 248
19: 65
39: 109
59: 152
79: 162
99: 173
119: 183
139: 194
159: 209
179: 229
199: 249

The above conversion table is based US EPA AQI standard.

About the Air Quality and Pollution Measurement:

About the Air Quality Levels

AQI Air Pollution Level Health Implications Cautionary Statement (for PM2.5)
0 - 50 Good Air quality is considered satisfactory, and air pollution poses little or no risk None
51 -100 Moderate 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. Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
101-150 Unhealthy for Sensitive Groups Members of sensitive groups may experience health effects. The general public is not likely to be affected. Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
151-200 Unhealthy Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion
201-300 Very Unhealthy Health warnings of emergency conditions. The entire population is more likely to be affected. Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.
300+ Hazardous Health alert: everyone may experience more serious health effects Everyone should avoid all outdoor exertion

To know more about Air Quality and Pollution, check the wikipedia Air Quality topic or the airnow guide to Air Quality and Your Health.

For very useful health advices of Beijing Doctor Richard Saint Cyr MD, check www.myhealthbeijing.com blog.


Usage Notice: All the Air Quality data are unvalidated at the time of publication, and due to quality assurance these data may be amended, without notice, at any time. The World Air Quality Index project has exercised all reasonable skill and care in compiling the contents of this information and under no circumstances will the World Air Quality Index project team or its agents be liable in contract, tort or otherwise for any loss, injury or damage arising directly or indirectly from the supply of this data.



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