Indoor air pollution by carbon monoxide and nitrogen oxides

The results of an exploratory survey of indoor levels of carbon monoxide and nitrogen dioxide from gas-fired cooking and waterheating appliances in the Dutch cities of Arnhem and Enschede in the fall of 1980 are reported. Measurements were carried out electrochemically (Ecolyzer 2000) or with Draeger tubes in the case of CO and with Palmes diffusion tubes (5 to 8 days exposure) in the case of NO2. For CO, in 18% (27%) of the homes visited the limit of 600 (300) ppm in the flue gases was exceeded, whereas the Dutch Installation Code Standard of 50 ppm CO in room air was exceeded in 17% of the homes. The arithmetic mean value of the NO2 concentration in 286 homes was 118 micrograms/m3 with a range of 35 to 472 micrograms/m3. The corresponding figures for living rooms were 58 and 35 to 346 micrograms/m3, respectively. Outdoor NO2 concentrations were 2 to 3 times lower than indoor concentrations.