of smog and ultra-fine dust. The Pollution Control Department issued warnings that particulate levels had soared to 94 micrograms per cubic metre of air in some areas, almost double the safe limit of 50 mcg. Residents were urged to wear N95 or KN95 protective dust masks. Bangkok City Hall reassured residents that conditions will "permanently improve" in 11 years (2029) with the launch of many new and improved modes of public transport. Bangkok City Hall failed to mention that it is constructing 1,047 km of new roads due to be completed by 2029 or that in the decade 2008 to 2018 the number of cars registered in Bangkok rose from 5.9 million to 10.2 million. In January 2019, Bangkok authorities employed cloud seeding to ease air pollution in parts of the city. That month, high-pressure cannons were blasted around Bangkok's City Hall and other areas to combat the smog, leading to debate as to whether the method was effective at washing away the particularly harmful smaller particles. In January 2020, a National Institute for Development Administration survey showed that "81% of the 1,256 local residents questioned agreed that the [Thai] government" was ineffective at solving Bangkok's air pollution, with 2.7% of respondents approving the government's efforts. Field and forest burning Fires in Thailand fall into three main categories: forest fires, agricultural burning, and roadside burning. Forest fires are set deliberately, as they are thought to increase forest product yields, especially the earth star mushroom (Astraeus hygrometricus (Pers.) Morgan; or in Thai), which has seasonal availability and a high market price. In order to collect these fungi, local farmers use fire either to clear the forest floor to make it easier to find the mushroom or because fire is thought to stimulate the growth of this mushroom. The burning of agricultural fields and forested areas in Southeast Asia is a yearly event, mainly during the "burning season", January through March. It is particularly widespread in the northern and northeastern provinces of Thailand. Northern Thailand has the highest rates of lung cancer in the country. The incidence of other chest diseases and cardiac conditions is also high. According to the Bangkok Post, corporations in the agricultural sector, not farmers, are the biggest contributors to smoke pollution. The main source of the fires is forested area being cleared to make room for new crops. The new crops to be planted after the smoke