THIMPHU, Jan. 29 (Xinhua) -- As Bhutan opens up to modernization, the number of vehicles and pollution level are increasing, whereby threatening the small Himalayan country's pristine environment.

The constitution of Bhutan requires the government to maintain 60 percent of its total land under forest cover for all time to conserve its natural resources and prevent degradation of the ecosystem.

While the country maintains more than 60 percent forest cover and also conducts various mass plantation activities across the country annually, its pristine environment is increasingly threatened. One factor is attributed to the increasing number of vehicles in the country.

Bhutan with a population of about 700,000 has reported having more than 92,008 vehicles in total, as per the latest report by the Road Safety and Transport Authority (RSTA). This has been increase from more than 40,532 vehicles in 2008.

The road safety and transport authority has reported that the capital Thimphu has the highest number of vehicles with 47,753 followed by Phuentsholing with 32,134, while rest 18 districts have lesser than 6,000 vehicles.

The impact of having more vehicles in the country were visible with road congestion, especially in towns of Thimphu and Phuentsholing. Other impacts include felling of trees and environmental destruction caused by new roads into the mountains and expansion of old roads every year.

The National Environment Commission of Bhutan has reported that the increasing number of vehicles in the country also impacts the quality of air. The commission's report said there has been a constant increase in the concentration of atmospheric particulate matter (PM10) in Thimphu since 2004.

Officials said despite having policies such as revision of taxes on import duty and green tax in 2014, the number of vehicles purchased has not decreased.

Despite rise in pollution level and environmental impact, the increasing number of people migrating to urban cities always opt private vehicle over public transportation.