#ID: ID_BEI_DC
 #City: Beijing
 #Station: Dongcheng
 #Name: 东城东四
 #Latitude: 39.929
 #Longitude: 116.417
 #Timezone: +0800
 Date,PM10,PM25,CO,Ozone,Sulphur Dioxide,Nitrogen Dioxide,AmbientTemperature,RelativeHumidity,WindDirection,WindSpeed,Pressure,RainGauge
 Unit,ug/m3,ug/m3,ppm,µg/m3,µg/m3,µg/m3,°C,%,°,m/s,hPa,mm
 10/29/2016 13:00,16,3,,58,10,3,32,66,200,3,1001,0
 10/29/2016 14:00,19,8,,57,9,4,32,64,197,2,1001,0
 10/29/2016 15:00,15,9,,52,47,17,30,72,190,2,1001,0
 10/29/2016 16:00,31,19,,52,34,17,30,75,191,2,1001,0
 10/29/2016 17:00,31,17,,49,49,19,29,75,194,1,1002,0
 10/29/2016 18:00,37,18,,45,55,25,29,73,183,1,1003,0
 10/29/2016 19:00,24,13,,40,21,19,29,80,65,1,1004,0
 10/29/2016 20:00,39,22,,44,4,16,28,85,7,1,1005,0
 10/29/2016 21:00,24,16,,43,3,7,28,85,10,1,1005,0
 

This is an example based on an HTML format (direct url: publishingdata/html/):

This is an example based on JSON format (direct url: /publishingdata/json/)

For instant particule counters, such as the Plantower PMS or Nova SDS, which provide instantaneous (in few seconds) particulate matter readings, the data is usually reported every minute. This data is usually computed based on several "averaged" readings from a one or two minute period.

The use of averaging is however not good enough, especially for failing sensors (or sensor close of end-of-life). Therefore, for such sensors, it is required to provide additonal metrics, such as the median, min, max, and standard-deviation. See for example the readings object in the below JSON data feed.

..

You can use the following arduino-compatible code to collect those metrics:

class Accumulator 
{ 
    #define OUTPUT_BUFFER_SIZE 120 
    char buffer[OUTPUT_BUFFER_SIZE]; 
 
    #define MAXACCVALUES 120 
    int vals[MAXACCVALUES]; 
 
    int count = 0; 
 
public: 
    Accumulator() 
    { 
        reset(); 
    } 
 
    void reset() 
    { 
        count = 0; 
        for (int i=0;i< MAXACCVALUES;i++)  
        { 
            vals[i]=0; 
        } 
    } 
 
    bool hasData()  
    { 
        return count!=0; 
    } 
 
    std::string output()  
    { 
        if (!hasData()) return std::string("{}"); 
 
        sprintf(buffer, OUTPUT_BUFFER_SIZE, "{\"min\":%d,\"max\":%d,\"median\":%d,\"average\":%.1f,\"stddev\":%.1f,\"count\":%d}",  
            vmin(), vmax(), median(), average(), stddev(), count); 
 
        return std::string(buffer); 
 
    } 
 
    void add(int val) 
    { 
        if (count==MAXACCVALUES-1) { 
          for (int i = 0; i < MAXACCVALUES - 1; i++) { 
            vals[i] = vals[i + 1]; 
            } 
            count --; 
        } 
        vals[count++]=val; 
    } 
 
    float stddev()  
    { 
        if (!hasData()) return -1; 
        int u  =avg(); 
        int t = 0; 
        for (int i=0;ivals[j]) { 
                    float t = vals[j]; 
                    vals[j]=vals[i]; 
                    vals[i]=t; 
                } 
  
            } 
        } 
        return vals[count/2]; 
    } 
 
    float avg()  
    { 
        if (!hasData()) return -1; 
        float t = 0; 
        for (int i=0;ivals[i]) { 
                t=vals[i]; 
            } 
        } 
        return t; 
    } 
 
    float vmax()  
    { 
        if (!hasData()) return -1; 
        float t = vals[0]; 
        for (int i=0;it) { 
                t=vals[i]; 
            } 
        } 
        return t; 
    } 
};

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.