July saw an improvement in the air quality of the six Indian cities that were monitored compared to June. All the cities reported more Satisfactory days than Moderate days last month. This could be the result of increased rainfall across the country which is known to bring down the pollution in the air.
In total there were 77 days that were reported to have Satisfactory air quality and 41 days that had Good air quality – a massive improvement compared to June when there were just 29 days that were reported as having Good air quality.
Delhi and Ahmedabad continued to top the table for the worst air quality in India while Bangalore and Hyderabad had the best air quality in July.
Missing Data Days
The total number of days for which data was missing for the six cities analyzed increased from 17 to 19 in July. However, the total number of missing data days any one city decreased. Although the total number of missing data days has gone up, we take it as a positive that individual cities reported much lower missing data days than before.
Air Quality Over Time
Delhi’s air quality see-sawed through-out the month, starting off high as it ended on a high in June. It plummeted for a couple of days before spiking back up and finished the month back at reasonable levels. Other cities in India saw consistent levels of pollution with little variation over the month.
US Consulate Data
Over that last several months, the US Consulate data has proven to be a reliable source of information about the air quality in India. However, things changed in July and there were many days where no pollution levels were available.
In particular, the data coming from the US Consulate in Kolkata has seen severe problems, at one point reporting negative pollution levels!
With that said, the chart below clearly shows an improving air quality as pollution levels decrease. This could be due to several factors, most likely due to the North West Monsoon which has seen many cities get plenty of rainfall. This weather pattern has cleared the skies over the cities from most of the pollution.
It’s interesting to note, however, that the official NAQI numbers do not follow a similar downward trend. This could be because the NAQI reports the air quality based on the highest concentrate of pollutant.
The chart below breaks down the air pollution levels by day. It’s very interesting to note that Delhi has recorded a number of days where the air pollution is better than Chennai and Hyderabad. On the flip side it has also reported more days that are Unhealthy or worse compared to the other cities. This is most likely due to the rainfall within the city.
Mumbai continues to surprise everyone by consistently recording lower pollution levels compared to all other cities. This could be a function of where the air quality monitoring stations are located or because of the weather patterns over the city.
In line with the official air quality index from the Indian Government, the US Consulates in India also reported better air quality in July with more days rated as Good and Moderate than in July.
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