Descriptive Analysis

The analysis is conducted on selective AQI Categories for the purpose of measuring the air trends for the yearly and intervals of 6 hours for the AQI Categories of “Very Unhealthy”, “Unhealthy” and “Unhealthy for Sensitive Groups” respectively.

BEIJING AIR QUALITY TREND

SAS outputs are tabulated to better understand the air trends of the city of Beijing. Taking year 2015 as the base year serves a starter for the comparative study.

"Very Unhealthy" counts for year 2016 has experienced a slight decline followed by a drastic fall in following years starting at 68 then making its way to 71, 47, 39 and finally 27.
"Unhealthy" counts increased to 495 in 2016 followed by a steady and gradual decline in the following years starting 415 then making its way to 404, 312, 281 and finally 172.
"Unhealthy for Sensitive Groups" counts remained higher than the counts for 2015 and stayed high for the most part i.e., 226, 2260, 255, 280, 248. However, a significant decline in 2021 of 113 can be observed.
Overall, Beijing has experienced an improved air quality for each passing year.

Comparing Six-hourly AQI trends to explore how daily hours affected the air quality.

"Very Unhealthy" remained high starting 12a.m to 6a.m, lessened in the afternoon but shot down to 117.
"Unhealthy" counts are high and dropped a little for the rest of the hours.
"Unhealthy for Sensitive Groups" counts was highest at 12a.m and remained low throughout the whole day.
Overall, Hours 12p.m and 6p.m had a much better air quality in comparison to 12a.m and 6a.m

GUANGZHOU AIR QUALITY TREND

SAS outputs are tabulated to better understand the air trends of the city of Guangzhou. Taking year 2015 as the base year serves a starter for the comparative study.

"Very Unhealthy" counts kept dropping from 12 in the year 2015 to 4 in 2021. Three records of 0 counts can be observed.
"Unhealthy" counts remained highest of 283 for year 2015. Gradual decrease was experienced through 183, 214, 173 followed by a drastic decrease from 113 to 53, to the lowest of 35 in year 2021.
"Unhealthy for Sensitive Groups" counts dropped steadily and gradually throughout the following years starting 183, 214, 173, 113, 53, 35.
Overall, Guangzhou has experienced an improved air quality for each passing year.

Comparing Six-hourly AQI trends to explore how daily hours affected the air quality.
"Very Unhealthy" counts haven't increased much at 6a.m either, and a decline is seen with the same at 12pm and 6p.m.
"Unhealthy" numbers are the most at 12 a.m; and the decrease little by little at 6 a.m, 12 p.m and 6 p.m.
"Unhealthy for Sensitive Groups" numbers have been the highest with 488 at the starting. A small decline was observed followed by an immediate shoot to 500 at 6p.m.

SHANGHAI AIR QUALITY TREND

SAS outputs are tabulated to better understand the air trends of the city of Shanghai. Taking year 2015 as the base year serves a starter for the comparative study.

"Very Unhealthy" counts are observed to be declining each year as 2015 is the highest 43; followed by 20, 9, 10, 6, 9, 0.
"Unhealthy" counts were the highest by 368 in 2015 falling to 374, 299, 118, 235 and 137 for the following years. 2021 saw the lowest count by 81.
"Unhealthy for Sensitive Groups" counts hit highest in 2015 as well. Following a gradual decline the counts 334, 342, 136, 325, 218 with 2021 being the lowest at 120.
Overall, Shanghai has experienced a very improved air quality for each passing year.

Comparing Six-hourly AQI trends to explore how daily hours affected the air quality.

"Very Unhealthy" is observed to be the highest although very few counts, still a decline was seen at 6 a.m, 12 p.m and 6 p.m also.
"Unhealthy" has a concerning number of counts which is observed to go up and down the entire day in disorderly and unsystematic manner.
"Unhealthy for Sensitive Groups" has a huge count of 450 at 12 a.m with a short decline at 6 a.m; and an alarming increase of 488 and 482 at 12 p.m and 6 p.m respectively.

SHENYANG AIR QUALITY TREND

SAS outputs are tabulated to better understand the air trends of the city of Shenyang. Taking year 2015 as the base year serves a starter for the comparative study.

"Very Unhealthy" count was the highest in the year 2015 and steadily declined the following years making its way to 56, 74, 15, 38, and 40. The healthiest air was experienced in the year 2021 with only 11 counts.
"Unhealthy" count was at an alarming count of 649 which drastically fell to 489, 288, 345, 298 and 316. The cleanest air was experienced in the year 2021 with only 75 counts.
"Unhealthy for Sensitive Groups" count was 267 for the year 2015 followed by a disorderly count of 384, 259, 274, 296 and 285. The counts for year 2021 drastically dropped to 33 which means there was a huge absence of this criteria.
Overall, Shenyang has experienced an improved air quality for each passing year.

Comparing Six-hourly AQI trends to explore how daily hours affected the air quality.

"Very Unhealthy" starts at a medium range at 12 a.m and shoots up to high ranges at 6 a.m and 12 p.m. The lowest count for the same was experienced at 6 p.m.
"Unhealthy" has an alarming count at 12 a.m which increases further at 6 a.m. Although 12 p.m sees a slight drop, 6 p.m is where least count is available.
"Unhealthy for Sensitive Groups" is the highest at 12 a.m then steadily drops

AQI Pattern Analysis

BEIJING AIR QUALITY INDEX

Violin Graphs for AQI Distribution throughout the Years

The overall air quality from 2015 to 2021 can stay at the level below 200. The trend of the maximum level tends to go down especially in 2018, the neck of the violin is the shortest among all those years. In 2019, the maximum level tends to go up again, but it is not as bad as 2015. Overall, there is improvement in the air quality in China. However, when compared to the WHO target, China needs to put more effect in controlling the air quality.

Boxplot depiction of the AQI data on monthly basis for the city of Beijing

Boxplot depiction of the AQI data on monthly basis for the city of Guangzhou

Boxplot depiction of the AQI data on monthly basis for the city of Shanghai

Boxplot depiction of the AQI data on monthly basis for the city of Shenyang

We are using SAS output function to graph the monthly box plot that enables us to see the patterns of AQI levels. The crucialpoint to be noted is that the geographic location does affect the AQI levels of some cities. Beijing and Shenyang are located in the northern part of China, whereas Shanghai is on the central coast and Guangzhou is located in the southern part of China. Due of the extreme cold weather in Beijing and Shenyang, residents in the suburbs and rural areas use coal-fired heating techniques to keep their homes warm which seems like the main cause and issue of air pollution. From the monthly boxplot of Beijing and Shenyang, we can see the AQI levels are higher in winter months like January to March and October to December. Around April to September each year, the AQI level is dropping significantly. In Shanghai, the pattern of AQI level is similar to Guangzhou, there are less outliers compared to Beijing and Shenyang. In 2021, Shenyang only has two months data while Guangzhou and Shanghai have 5 months. In addition, Beijing has 6 months of data. This makes it hard to compare the data between cities for this particular year.

The box plot shows that there are more outliers in winter months than in summer months. There is significant improvement in the AQI level in the winter season from 2015 to 2020. In spring/ summer time (between April and June), there is no noteworthy differences among all the years. Although, there is a slight drop between July and September.

The stacked bar chart shows that the air quality between May and October is better than the other months. It is especially well in August, the AQI level did not reach “very unhealthy.” In November to December, and January to April, the level of “unhealthy” is higher than the level of “unhealthy for sensitive groups”. This explains the chilly weather for some cities that caused the consumption of coal to be burned.

The AQI level in 2018 and 2019 had dropped and raised again in 2020 and 2021. According to the information from ‘healthy and safety Shanghai,’ there was a second action plan launched in 2018. Thousands of inspectors had been sent to Beijing-Tianjin-Hebei, the Yangtze River Delta and the Fenhe and Weihe River to expose the environmental issues. The inspection had been completed by the end of April 2019. This might explain why the level had dropped in 2018 and 2019.

AQI Category Frequency Table & Graphs Grand Total for All Years in China

From the Grand Total of AQI Categories for all years from 2015 to 2021, we can see that the aggregate count of all three categories peaked in 2015, then began to decline with each passing year in 2021 the count was the lowest at 818. 
In all the years, the category Unhealthy has the highest frequency count of 7694, while Very Unhealthy has the lowest frequency count of 1014.
The highest count for Unhealthy for Sensitive Groups was in the year 2016 with a count of 1227.
Very Unhealthy frequency counts are again from Year 2015.
The year 2021 had the lowest count of Unhealthy 363, Unhealthy for Sensitive Groups 412 and Very Unhealthy 43. This gives us a total of 818. Even after totalling the bad air quality it is significantly lower than the frequencies of other years.
This proves the air quality improved to a great extent where bad air was regulated to a minimum.
We can conclude by saying the year 2020 has experienced the lowest trends of bad air quality with a total number of 1849 frequency counts.
For year 2021, if the air quality remains the same the next rest of the months we can say it has been majorly healthy too.

The above stacked bar chart graph for AQI Category depicts the data of all the years combined grouped into months for denoting their respective frequencies.
The frequency counts of "Unhealthy" has the most number of frequencies, just a little below 8000 on the stacked bar chart. According to the frequency table this corresponds perfectly with the value 7694.
"Unhealthy for Sensitive Groups" has the frequency a little lesser than that of the "Unhealthy" group which may verified with the table value for being 7158.
"Very Unhealthy" is clearly seen as the smallest stack among them all 1014 entries to be exact. This is a good sign as the unhealthiest air is on check and minimal.

The above plotted are AQI Categories of all years combined for the cities of Beijing, Guangzhou, Shanghai and SHneyang respectively. It depicts the exact number of Unhealthy, Unhealthy for Sensitive Groups and Very Unhealthy air quality ranges of China. It can be observed that there is an alarming rate and number of bad air quality prevailing in the atmosphere for China but due to measures we can observe the air quality improving too.

Line Graph for Comparative Study using City-wise AQI Categories

Shanghai and Guangzhou have similar line patterns and it is a mountain peak type shape. The peak is in the groups of ‘Unhealthy for Sensitive Groups”, then all the way down the hill peak is the group “Very Unhealthy”. On the other hand, the analysis throws light on the fact that Beijing is just like a negative slope, from “Unhealthy” it straightaway reaches the hill side of the group “Unhealthy for Sensitive Groups” and drops straight down again to “Very Unhealthy”

GUANGZHOU AIR QUALITY INDEX

SHANGHAI AIR QUALITY INDEX

SHENYANG AIR QUALITY INDEX

Descriptive Analysis

AQI Category Analysis

AQI Pattern Analysis