The worsening air pollution in Vietnam's capital, Hanoi, has led to the delay or diversion of all flights to and from the capital's international airport to other cities. According to Hanoi airport authorities, nearly 100 flights have been affected due to the environmental conditions. The Vietnamese airline "VietJet" reported that several of its flights scheduled to land in Hanoi have been diverted to Hai Phong city. The company "AirVisual," which specializes in monitoring air quality indices, indicated that levels of hazardous fine particles known as "PM 2.5" in the air in Hanoi reached an extremely high level of 257 micrograms per cubic meter early today.