During these months, several interior provinces were found to be the most polluted. While cities along eastern and southern coasts had high levels of fine pollutants, the report did show that the levels in these areas were lower than the same time period last year.
Some analysts reason that the drop could be the result of government policies enacted in late 2013 to limit coal use in some of China's most crowded areas.
Researchers at Greenpeace East Asia, which is based in Beijing, ranked 360 cities after looking at levels of fine particulate matter called PM2.5, considered more dangerous than other forms of pollutants because it can penetrate deep into the lungs and enter the bloodstream, causing a host of health issues.
Air monitors in 367 Chinese cities record the levels of PM2.5 and other kinds of pollutants hourly, and the data was released with the approval of the Ministry of Environmental Protection. Greenpeace said data was discarded from seven cities that were monitored due to flaws in the reporting process.
The average concentration of PM2.5 in the remaining 360 cities was 66 micrograms per cubic meter, nearly twice the national standard of 35 micrograms per cubic meter. The average was more than two and a half times the exposure limit recommended by the World Health Organization.
That limit is 25 micrograms per cubic meter over a 24-hour period.?Only 32 cities in China met the national air quality standard, while 141 cities, or nearly 40 percent, had PM2.5 levels that were more than twice the standard.
The most polluted provinces were Henan, Hubei and Hebei. Beijing ranked fourth, and Shandong, on the east coast, was fifth. The heavy industrial factories that surround these areas rely mostly on coal for power.
The three most polluted cities were Baoding, a manufacturing town in Hebei where steel is produced and forged; Kashgar, a traditional Silk Road oasis town in the far western region of Xinjiang; and Xingtai, another industrial factory town in Hebei. The three cleanest cities were all in the far west: Linzhi in Tibet, Lijiang in Yunnan Province and Altay in Xinjiang.
Despite a recent drop in the growth rate of coal use, China continues to have among the most polluted cities in the world, alongside urban centers such as those in India and Iran.
The environmental crisis is a major concern to ordinary Chinese citizens, one which creates a great deal of discontent among China's residents The Communist Party leaders are aware of this and have recently tried to enact policies to reduce pollution, however many doubt their efforts are sincere.
Zhang Kai, a researcher at Greenpeace East Asia who helped oversee the report, said in an email interview that there was some positive news. He said Greenpeace believed that policies the central government announced in September 2013 to limit coal use in three major population centers had actually led to notable drops in PM2.5 levels.
While Beijing, had a nearly 13 percent drop in PM2.5 concentration levels from the same three-month period in 2014. The average level in Beijing was 92.4 micrograms per cubic meter, which is still nearly four times the recommended limit set by the World Health Organization.
There have been some recent concerns about the methodology used in the government's air-monitoring however. Wind pattern are not taken into consideration and could give a false impression that PM2.5 levels are dropping. One report estimates that with weather patterns accounted for, PM2.5 levels in 2013 and 2014 were actually worse than in the two years previous.