Worsening symptoms: dyspnoea, sputum purulence or sputum amount, nasal discharge/congestion, wheeze or tight chest and upper respiratory symptoms*
| Pollutant | OR† (unit change) (95% CI) | p Value | Estimate‡ (per IQR change) |
| Dyspnoea n=77 | |||
| NO2 (ppb) | 1.003 (0.997 to 1.008) | 0.338 | 1.036 |
| O3 (ppb) | 1.005 (0.995 to 1.016) | 0.335 | 1.078 |
| SO2 (ppb) | 0.996 (0.980 to 1.013) | 0.662 | 0.978 |
| PM10 (μg/m3) | 1.006 (1.002 to 1.011) | 0.008 | 1.125 |
| Black smoke (μg/m3) | 1.003 (0.994 to 1.012) | 0.526 | 1.027 |
| Sputum changes n=68 | |||
| NO2 (ppb) | 1.006 (0.999 to 1.013) | 0.085 | 1.085 |
| O3 (ppb) | 1.007 (0.992 to 1.022) | 0.370 | 1.099 |
| SO2 (ppb) | 1.008 (0.988 to 1.029) | 0.446 | 1.042 |
| PM10 (μg/m3) | 1.004 (0.997 to 1.011) | 0.251 | 1.082 |
| Black smoke (μg/m3) | 1.004 (0.992 to 1.016) | 0.536 | 1.035 |
| Nasal discharge or congestion n=70 | |||
| NO2 (ppb) | 0.999 (0.991 to 1.006) | 0.690 | 0.979 |
| O3 (ppb) | 0.984 (0.970 to 0.998) | 0.023 | 0.794 |
| SO2 (ppb) | 1.011 (0.994 to 1.030) | 0.209 | 1.072 |
| PM10 (μg/m3) | 1.003 (0.997 to 1.010) | 0.296 | 1.067 |
| Black smoke (μg/m3) | 1.003 (0.992 to 1.013) | 0.598 | 1.026 |
| Wheeze or tight chest n=70 | |||
| NO2 (ppb) | 1.002 (0.996 to 1.009) | 0.460 | 1.033 |
| O3 (ppb) | 0.992 (0.977 to 1.007) | 0.274 | 0.890 |
| SO2 (ppb) | 1.002 (0.986 to 1.019) | 0.785 | 1.014 |
| PM10 (μg/m3) | 1.004 (0.998 to 1.009) | 0.187 | 1.071 |
| Black smoke (μg/m3) | 1.002 (0.993 to 1.010) | 0.722 | 1.014 |
| Upper respiratory symptoms n=73 | |||
| NO2 (ppb) | 0.999 (0.990 to 1.008) | 0.849 | 0.988 |
| O3 (ppb) | 0.987 (0.969 to 1.005) | 0.143 | 0.829 |
| SO2 (ppb) | 0.991 (0.971 to 1.012) | 0.392 | 0.947 |
| PM10 (μg/m3) | 1.000 (0.993 to 1.007) | 0.928 | 0.994 |
| Black smoke (μg/m3) | 1.007 (0.990 to 1.024) | 0.435 | 1.062 |
↵* In addition to individual pollutants (previous day), each model includes outdoor temperature (average of the minimum and maximum) and season (four categories) plus control for autocorrelation.
↵† ORs are for a 1 unit change in pollutant level (ppb for NO2, O3, SO2; μg/m3 for PM10, black smoke).
↵‡ ORs are for an IQR change in pollutant level.
PM, particulate matter.