Table 1 Systematic review methodology

Objectives

Review articles from the past 12 years that explicitly investigate interactions between air pollution and material resources or between air pollution and stress on cardiovascular events/indicators.

Eligibility Criteria

1) Published from 2005 to 2016

2) Written in English

3) Published in a peer-reviewed journal.

4) Study of human effects

5) Explicitly seek to evaluate the impact of interactions between air pollution and social factors on cardiovascular outcomes

6) Primary research study, excluding abstracts, reviews, meta-analyses and op-eds

7) Any study design

Information sources

MEDLINE® database, accessed via PubMed®

Search strategy

Searches conducted using all combinations of the following three categories of terms connected with the Boolean operator AND:

1) Exposure to specific pollutants as listed below: “fine particles” (which signify PM less than 2.5 μm in aerodynamic diameter or PM_2.5), “PM”, “ultrafine particles” (which signify PM less than 0.1 μm in aerodynamic diameter or UFP), “UFP”, “nitrogen dioxide”, “NO₂”, “particle number”, “PNC”, and “ozone”.

2) Interaction with or effect modification by socioeconomic position as given by the listing of the following terms: “socioeconomic status”, “SES”, “socioeconomic position”, “SEP”, “income”, “education”, “material resources”, “chronic stress”, “psychological stress”, “psychosocial stress”

3) Human health outcomes related to cardiovascular health including the following terms: “cardiovascular”, “mortality”, “inflammation”, “blood pressure”

Data management

Records were imported and organized using Excel and EndNote™

Selection process

1) Enter search terms into PubMed

2) Import identified citations into Excel

3) Review papers for inclusion criteria– Level 1 (Screening)

4) Save studies for inclusion

5) Review references of selected articles for additional studies – Level 2 (Reference Review)

6) Review newly identified studies for inclusion

7) Read all included studies for results– Level 3 (Full Review)

Data Items

Information collected on the following types of data from the articles: publication year, language, study design, participants, air pollutant exposure, modifier/susceptibility, health outcomes

Risk of bias

A qualitative assessment of bias was made based on the study design. In the final manuscript we include a statement potential and implications of bias among all papers.

Confidence in cumulative evidence

Qualitative assessment was made based on the number of studies, results, study designs and sample size