| Age |
Age-dependent increase10,12,13,14,15
|
| Gender |
Boys >Girls13,15,19
|
| Race/ethnicity |
Asians higher than whites10,12,13,19
|
| Hispanic children higher than non-Hispanic white children13
|
| Height |
Rise by height gained12
|
| Nitrate containing food |
Increase21
|
| Caffeine |
Conflicting results24,25
|
| Respiratory tract infection |
Unclear26,27
|
| Circadian rhythm |
Unclear10
|
| Exercise |
Transient reduction23
|
| Spirometry, bronchial challenge test, sputum induction |
Transient reduction30,31
|
| Smoking |
|
| Active |
Reduction22,55
|
| Passive |
Transient reduction56
|
| Atopy |
Increase17,32,33,34,38
|
| Outdoor air pollution |
|
| Ozone, NO2, PM2.5, PM10, elemental carbon |
Increase by acute and chronic exposure43,44,45,46
|
| Indoor air pollution |
|
| Electric baseboard heating |
Increase49,50,51
|
| Woodstoves, candles, gas cooker |
Not associated52
|
| Polyvinyl chloride material |
Unclear53,54
|
| Medication |
|
| Inhaled or systemic corticosteroid |
Reduction28
|
| Leukotriene receptor antagonist |
Reduction29
|
