A metabolic equivalent was allocated to each physical activity using the values developed by Ainsworth et al. For each respondent the total number of hours spent on moderate or vigorous activities was calculated.
Antipsychotic medications were converted to chlorpromazine equivalents using the conversion values developed by Leucht and colleagues [ 34] and Woods [ 35].
To get a sense of relative health risks associated with estimated ambient concentrations of HAPs, and to set category thresholds, we used health-related toxicity values developed by either the U.S. EPA or the California Office of Environmental Health Hazard Assessment OEHHAA), whichever was more stringent (health protective), (Cal EPA and OEHHA 2002; Cal OEHHA 2005; U.S. EPA 2005, 2006c, 2006d).
Hence, we also use a functional group (HFG) entropy value developed by (Atchley et al. 1999) based on eight groups of AAs, which accentuates similarity between AAs and variability in functional changes.
When an AEGL-3 value was not available a Protective Action Criteria (PAC) value, developed by the United States Department of Energy, was used [ 27].
We examined the distribution of lifetime risk estimates and calculated age-sex centile values using methods developed by Royston 21 and compared the distribution with the 10 year risk estimates derived from QRISK2 (2010).
Therefore, for the US model, the SGRQ total score was mapped to utility values using the algorithm developed by Starkie et al. 28 The SGRQ data by COPD severity at baseline from the ACCORD I trial was used as the basis for the mapping.
The SF-12 health survey outcomes collected at baseline, 4, 12 and 24 weeks were mapped onto EQ-5D utility values using an algorithm developed by Gray et al. [30].
We additionally report coefficient of determination (R) values using a method developed by Xu (2003) for random intercept mixed models: where β is the slope of the model, σ is the residual variance, and σ x is the variance of the independent variable.
The exact P-values associated with the observed chi-square statistic values were computed using a method developed by Mehta et al., which are implemented in the statistical analysis system.
