Indoor nitrogen dioxide (NO2) levels and lung function and respiratory symptoms/diseases in selected studies of adults
| First author [ref no.] | Country of study | Risk factor | Disease/condition | |
| Simoni 23 | Italy | NO2 exposure high versus low (in subjects | PEF variation | OR (95% CI) |
| with chronic bronchitis) | Max amplitude | 2.03 (1.14–3.61) | ||
| Diurnal variation | 1.84 (1.05–3.24) | |||
| NO2 exposure high versus low (in all subjects) | Respiratory illness | 1.50 (0.96–2.33) | ||
| Pilotto 27 | Australia | Presence of gas heaters indoors: yes versus no | Asthma | 3.30 (1.40–7.64) |
| Moran 26 | Britain | Fuel used for cooking: gas versus electricity | Lung function | Variation mL |
| FEV1 | −70 | |||
| FVC | −35 | |||
| Ng 28 | Singapore | Frequency of gas cooking: high versus low | FEV1 | −10 |
| Ng 28 | Singapore | Frequency of gas cooking | Breathlessness | Prevalence % |
| Low | 16.9 | |||
| High | 23.3 |
OR: odds ratio
CI: confidence interval
PEF: peak expiratory flow
FEV1: forced expiratory volume in one second
FVC: forced vital capacity