Separate statistics from the Ministry of Health agree that the ratio of people with respiratory diseases is getting higher each year - and pollution gets the main blame.

Statistics from the Ministry of Transport revealed that 2.5 million patients spend an estimated US$66.8 million a year for examinations and treatment for respiratory diseases each year in Ha Noi alone.

They also show that in HCM City, 5.6 million patients spend $70.9 million a year for similar treatment.

The Ministry of Environment and Natural Resource' s report also shows that most big cities throughout Viet Nam are facing increased levels of air pollution particularly ozone (O3) and dust.

The report, which focuses on air quality from 2008-13, reveals that for several years, the air quality in Ha Noi has been poor four days out of 10.

In Da Nang City, the number of "poor" days grew three times in the two years between 2011 and 2013.

Deputy Environmental Minister Bui Cach Tuyen blamed the declining air quality on an increase in vehicles and other human activities.

Ozone levels throughout the country were highest between 9-11am as the cities sprang to life. However, there were also periods when it was also very high at night, the report said.

Tuyen said that many workshops were held to find the cause of the high night levels, without success.

The environmental report said that the increase in ozone and other pollutants level in the air can could cause respiratory diseases, including asthma and bronchitis.

In Ha Noi, HCM City, Bien Hoa and Quang Ninh, dust levels were two-to-six times higher than allowed.

In the central region, including Da Nang, dust levels were 42 per cent higher than permitted in key economic zones.

In the southern region, including HCM City, levels were 44 per cent higher than permitted.

However, in the north, they were an alarming 68 per cent higher than allowed.

Cases of tuberculosis are on the increase in both was HCM City and Ha Noi.