WAQI client for MATLAB

WAQI (World Air Quality Index) provides open API for reading air quality data from the stations registered on the project.

Get your API token

Request the WAQI API access token at https://aqicn.org/api/.

Usage

Air quality data for the given location

token 
=
 
"
<your token>
"
;
aqi 
=
 
waqi
.
WAQI
(
token
);

%
 Get data for the given known city
bangkok 
=
 
aqi
.
city
(
"
bangkok
"
);

%
 Get data from the nearest station for given coordinates
seattle 
=
 
aqi
.
nearest
([
47.62050
, 
-
122.34930
]);

Plot received forecast data:

forecast 
=
 
seattle
.
Forecast
.
pm25
;

figure
plot
(
forecast
.
Time
, 
forecast
.
Avg
, Color
=
"
black
"
, LineWidth
=
1.5
, Color
=
[
0
, 
0.3
, 
0.5
])
title
(
"
Air Quality Forecast
"
)
hold
 
on
plot
(
forecast
.
Time
, 
forecast
.
Max
, Color
=
[
0.6
, 
0.6
, 
0.6
])
plot
(
forecast
.
Time
, 
forecast
.
Min
, Color
=
[
0.3
, 
0.3
, 
0.3
])
legend
([
"
Avg
"
, 
"
Max
"
, 
"
Min
"
], Location
=
"
northwest
"
)
hold
 
off

List of stations for the given geographical area

%
 Geographic boundary
chiang_mai_area 
=
 [
    
geopoint
(
19.05580
, 
98.53775
)
    
geopoint
(
18.41727
, 
99.32121
)
];

%
 Get list of stations
result 
=
 
aqi
.
stations
(
chiang_mai_area
)

Result includes locations of returned stations, station information and current readings of AQI:

Display stations on the map:

station_names 
=
 [
result
.
Station
.
Name




];
station_descriptions 
=
 
arrayfun
(@(
a
, 
t
) 
sprintf
(
"
AQI: %.0f<br/>Measured: %s
"
, 
a
, 
string
(
t
, 
"
M/dd/yyyy hh:mm:ss XXX
"
)), 
result
.
AQI
, 
result
.
Timestamp
);

colors 
=
 
cell2mat
(
arrayfun
(@
colorcode
, 
result
.
AQI
, UniformOutput
=
false
));

wmmarker
(
result
.
Location
, FeatureName
=
station_names
, Description
=
station_descriptions
, Color
=
colors
);

%
 A helper function to color code values of AQI
function
 
color
 
=
 
colorcode
(
aqi
)
    
if
 
aqi
 
<=
 
50
        
%
 Good
        color 
=
 [
0
, 
153
/
255
, 
102
/
255
];
    
elseif
 
aqi
 
<=
 
100
        
%
 Moderate
        color 
=
 [
1
, 
222
/
255
, 
51
/
255
];
    
elseif
 
aqi
 
<=
 
150
        
%
 Unhealthy for Sensitive Groups
        color 
=
 [
1
, 
153
/
255
, 
51
/
255
];
    
elseif
 
aqi
 
<=
 
200
        
%
 Unhealthy
        color 
=
 [
204
/
255
, 
0
, 
51
/
255
];
    
elseif
 
aqi
 
<=
 
300
        
%
 Very Unhealthy
        color 
=
 [
102
/
255
, 
0
, 
153
/
255
];
    
else
        
%
 Hazardous
        color 
=
 [
126
/
255
, 
0
, 
35
/
255
];
    
end
end

Air quality data for a specific station

%
 Find station with the worst AQI
[
~
, 
i
] 
=
 
max
(
result
.
AQI
);
worst_station 
=
 
result
.
Station
([
i
(
1
)]);

%
 Get air quality data for given station
measurements 
=
 
aqi
.
station
(
worst_station
)