We measured Particle Number Concentration (PNC) along driving and walking routes in urban and suburban Bangkok and rural Thailand to assess potential public exposure to submicron and ultrafine aerosol particles. Compared with typical UK concentrations in similar environments, Thailand values were significantly higher, especially roadside and rural (1-2 x typical UK values) and urban background (up to 6 x). As well as road traffic, strong local sources included canal boats and street food stalls.
