Article in beijing Mysterious Pneumonia Outbreak Raises Concerns in China, WHO Seeks Information Chinese hospitals have reported an increase in cases of undiagnosed pneumonia since early October, particularly among children. Delhi's air is no better than Beijing's A World Health Organization (WHO) report has revealed city's deteriorating air quality. Delhi's PM2.5 levels ranged from 130 to 565 mg/cu m, when the safe level of PM2.5 is 20 mg/ cu m. MORE FOR YOU