The heterogeneous reaction of nitric acid (HNO3) with nitric oxide (NO) on borosilicate glass surfaces was studied in a flow system at relative humidity levels in the range 21-86%. Reactant concentrations were kept closer to ambient atmospheric levels as compared to all previous studies of this reaction. Within experimental error, no formation of the proposed reaction products nitrous acid (HONO) and nitrogen dioxide (NO2) was observed. Upper limits of the reactive uptake coefficients of NO on borosilicate glass surfaces, covered with similar to1 monolayer of HNO3, were determined: gamma(NO-->HONO) < 4.0 x 10(-11) and gamma(NO-->NO2) < 2.5 x 10(-9). These values are significantly lower than previously reported values, which were determined at higher reactant concentrations. Results obtained upon investigation of the secondary heterogeneous reaction of the proposed product HONO with HNO3 under identical experimental conditions show that HONO should be observed in the study of the reaction HNO3 + NO, if it is formed. Thus, the obtained upper limit gamma(NO-->HONO) is representative for the reaction HNO3 + NO --> HONO + NO2. Under the assumption that the glass surfaces, typically used in laboratory studies of this reaction, are representative for environmental surfaces, the latter reaction is unimportant for atmospheric HONO formation and for a "renoxification" of the atmosphere.