Table 1.

Search Parameters.

Key terms	-indoor air pollution -household air pollution -predictors of indoor air quality -socio-economic status -deprivation -lifestyle factors
Inclusion criteria	-written in English
	-published after 2000
	-research conducted in the developed world
	-has been peer reviewed
	-concerns socio-economic factors which influence levels of indoor air pollution exposure
Post-hoc exclusion criteria	-studies which quantify exposure in low socio-economic households without a control population as a reference
	-studies which use race or ethnicity as the dependent variable instead of a socio-economic indicator
	-studies where socio-economic status is the effect modifier on a health outcome without quantifying the exposure disparity
Search string in SCOPUS	( TITLE-ABS-KEY ( household ) OR TITLE-ABS-KEY ( residential ) OR TITLE-ABS-KEY ( indoor ) AND TITLE-ABS-KEY ( air AND pollution ) OR TITLE-ABS-KEY ( exposure ) AND TITLE-ABS-KEY ( income ) OR TITLE-ABS-KEY ( depriv* ) OR TITLE-ABS-KEY ( socio* ) OR TITLE-ABS-KEY ( inequalit* ) OR TITLE-ABS-KEY ( unequal ) )

Table 1 outlining the main search parameters and an example search string. Note that the advanced search feature was used in all databases.