ISSS608 2018-19 T1 Assign Lee Yeng Ling Task 1 Insights

Spatio-temporal Analysis of Air Quality in Sofia City

Overview

Data Overview & Preparation

Application Design

Task 1 Insights

Task 2 Insights

Task 3 Insights

Conclusion

Task 1 Insights

Task 1: Spatio-temporal Analysis of Official Air Quality

'Characterize the past and most recent situation with respect to air quality measures in Sofia City. What does a typical day look like for Sofia city? Do you see any trends of possible interest in this investigation? What anomalies do you find in the official air quality dataset? How do these affect your analysis of potential problems to the environment?

Your submission for this questions should contain no more than 10 images and 1000 words.

About Sofia

Sofia, the capital of Bulgaria, is situated in a hollow valley at the skirts of the Vitosha mountain with population of about 1,300,000 people. The unfavourable meteorological conditions in the city, which is the most densely populated area in the country, surrounded by mountains up to 2,500m high, are combined with a number of different industrial, traffic and domestic air pollution sources which are subject to various monitoring programs and investigations.

About Sofia Pollution Issue

The national legislation following the EU Directive 2008/50/EC sets PM10 daily limit values of 50 μg.m3, not to be exceeded more than 35 times per calendar year. During 2012 and 2013, the mean annual PM10 concentration was above the limit value of 40 μg.m3 in all Sofia urban stations. The number of days with exceedances at five automatic monitoring stations varied between 59-108 days in 2012 and 62-110 days in 2013 (Report RIEW, 2013). Then air pollution with particulate matter in Sofia is characterized by a distinguished seasonal pattern with peaks during the cold period (winter season) of the year. This has been because of higher emissions from domestic heating during winter and more intensive urban traffic. Minimum concentrations are observed in the summer months, when the mixing conditions in the atmosphere are better and the source emissions are reduced. This has highlighted the need to evaluate the level of particulate pollutants spatially for policy and management action to reduce the air pollution levels in Sofia.

Annual Trend of Official Air Quality

Density Plot: Based on the density plot of Official Air Quality hourly PM10 concentrations from 2013 to Sep 2018, the average PM10 hit highest in 2014 but did not showed any improvement at Sofia city overall since 2015. There were often times when the PM10 exceed healthy limits (ie. exceeding 50) for all 5 stations. The ave hourly PM10 was a high of 286 on 31 Dec 2017 at Hipodruma Sofia station. Current Year (past 11 months) till Sep 2018: The chart shows that from end Nov 2017 to end of January 2018, the average PM10 concentrations were high across all the 5 official stations. The highest PM10 was at Mladost Sofia at 261.6 on 27 Jan 2018 and second highest was at Hipodruma Sofia at 245.1 on 27 Jan 2018.

Calendar Trend of Official Air Quality

Calendar Day: Having a full year calendar days view of each year for each station reveal that PM10 concentrations were high in the months of November to February and on weekends (Saturdays and Sundays) and Mondays generally. From the measurements of the 5 official stations, Sofia is still non-compliance with the national legislation following the EU Directive 2008/50/EC sets PM10 daily limit values of 50 μg.m3, not to be exceeded more than 35 times per calendar year. At many of the stations, it had exceeded more than 35 times for the past few years as well as the past year. The same trend as in the past are still observed, ie. highest during the winter (December through February) and lowest (with a few Good readings even) during Summer (June through August). Anomalies: Firstly, having a full year calendar days view of all years for each station shows missing values from 2 January 2017 to 27 November 2017. It thus raises the question that how could all stations failed at the same time during this period. Secondly, Druzhba Sofia station should record AQI "Good" readings from month February to September in 2018 as compared to "Moderate" & "Fair" readings in the past years (2013 to 2016). A question may be asked is whether the location of the station had been moved higher up to the mountains.

Potential Concerns Arising from Trend Analysis

The calendar view trends showed quite a large patch of AQI "Fair" (green) across all 5 air quality stations. However, these readings don't seem to reconcile (or too good to be "True") with the sentiments of population in Sofia city. Therefore, we will compare with the measurements from the Citizen Science Air Quality sensors readings in Task 2 before we could make further assessment.