The air pollution index soared to stratospheric levels in Hanoi on Monday and photos captured the smog that has blanketed the capital city. 

At 8 a.m. on Monday, a bird’s eye view shows smog giving Hanoi the look of a ghost city.

Hours earlier, at 4 a.m., AirVisual recorded Hanoi’s air quality index (AQI) at 385 - the highest level the city has witnessed this month.

AirVisual measures Hanoi's air quality based on 10 monitoring stations run by Hanoi authorities and four by non-profit organizations.

However, this result is vastly different compared to the AQI recorded by the automatic monitoring systems in Hanoi installed at various spots, which ranged from 147 – 162.

AirVisual showed the AQI on Nguyen Chi Thanh Street at 302 at 8 a.m., but Hanoi's monitoring station on Thanh Cong Street (1.2 km away) had it at 150.

The AQI, a metric used by multiple governmental agencies to determine how polluted the air is, ranges from 0 to 500, where high index values indicate higher levels of air pollution and higher potential for adverse health effects. Children, seniors and individuals with respiratory and heart diseases are recommended to avoid sustained and high-intensity outdoor exercises when AQI levels reach 150 or above.

According to the Vietnam-based PamAir, another environment monitoring, the index on Pham Hung Street stood at 201 at 7 a.m. Meanwhile, another monitoring system of Hanoi showed the AQI in My Dinh (1.8 km from Pham Hung) at 114.

Buildings are blurred by the smog in Long Bien bridge area at 8 a.m. on Monday. 

Over the Red River and the historic Long Bien Bridge, the landscape wore a hazy look at 8 a.m. Monday.

The smog looked no better at the West Lake area in Tay Ho District at around 9 a.m. The AQI was 250, according to AirVisual.

Hanoi authorities have pointed fingers at the large number of vehicles in the city’s central area as one of the main causes of air pollution.

They have also attributed it to a seasonal transition and termed it a periodical episode, as the city is in the transition from summer to fall and then winter.

The rapid pace of urbanization, with many constructions proceeding apace, has not helped with the matter. The above picture was taken on Sai Doi Street in Nam Tu Liem District on Monday morning. Locals have been exposed to dust for many months.

Many residents have voiced their concern, urging the city to take action, instead of offering excuses for worsening air pollution.