Abstract
NO2 concentrations on a roadway and its penetration effects into a vehicle cabin were measured using an NO2 sensor placed on a vehicle which can perform simultaneously real time monitoring on the road and in the car. The NO2 concentrations on the regional road, where the heavy duty truck ratio was high, was almost 150 ppb, and it was strongly affected by the heavy duty trucks ratio. The NO2 concentrations on the highway were high enough to exceed the daily average value of Japanese air quality standards at almost all locations, and it increased over 200 ppb at uphill with a high H. D. ratio condition. In a long tunnel on the highway, the maximum NO2 concentration reached 3 ppm. The NO2 concentrations in the car were the same as those on the road when its air conditioning was in the fresh air mode. It was found that changing the mode to internal circulation prevented NO2 penetration into the vehicles. However, in this situation, there will be the possibility of a high CO2 concentration due to breathing of the passengers. The NO penetration efficiency into the car was higher than that of NO2. The diffusion features of NO and NO2 from a roadway into a residential district were investigated by measuring NO and NO2. NO disappeared almost 100 % at a point 7 meters from the road, however, almost 50 % of the NO2 still remained. It is suggested that 150 ppb NO2, which is observed on regional roads might have some effects on close residential districts. These results indicated that pollutants on the road have a significant influence on passengers who travel in vehicle along the road and citizens who are living close to the road.
