•Simple and low-cost methods for evaluation of passive samplers for NO2 are described.•Colorimetric evaluation as alternative to photometric determination has been investigated.•Nitrite test-strips for reagent-less semi-quantitative evaluation of NO2-passive samplers have been examined.•A RGB-color sensor is proposed for improved detection and evaluation of test strips for nitrite.•Comparison was made of photometric procedures and proposed test strip evaluation for determination of NO2 in ambient air. Simplified procedures based on photometric and colorimetric detection have been developed and investigated for the determination of nitrite formed in passive sampling of NO2 with triethanolamine as sorptive medium. All procedures basically rely on the common Griess-Ilosvay reaction, but the experimental conditions are different. The variants evaluated are the application of liquid and solid reagents for photometric detection and a commercially available colorimetric test using a sliding color comparator. Furthermore, nitrite test strips were investigated. It was shown that solid reagent addition not only simplifies the analytical procedure but can provide higher sensitivity of the photometric assay. Colorimetric tests are inherently semi-quantitative, but results obtained - considering this restriction - were reliable and have the potential for fast determinations and at-site screening purposes. For the detection of nitrite in combination with passive sampling of NO2 they are attractive for low-budget educational purposes and citizen science projects and can serve for indicative monitoring. As an alternative to common spectrophotometers, an innovative LED-based photometer with WLAN/WIFI interface for smartphone-based data evaluation was investigated as a cheap and mobile-applicable detector for nitrite. Also reported is the development and application of a low-cost purpose-made reflectometer for evaluation of nitrite test strips. The color sensor module of the reflectometer - with light emitted from an inherent white LED - converts the reflected light from the test zone of the strips into RGB values. The relative intensity changes of the green color (complementary to the pink product of the Griess-Ilosvay reaction) can be correlated to the nitrite concentration of the sample solutions enabling improved concentration resolution of test strips compared with visual inspection. Ambient air measurements of NO2 were made and results obtainedof the analytical variants evaluated. Display omitted .