Table 3 Characteristics of the studies reviewed

Epidemiological studies on wildfire smoke

48

33

Wildfire smoke exposure (most using PM_2.5 or PM₁₀ as exposure metric) is associated with increased morbidity and mortality of IHD, HF, CAD, CHD, and arrhythmia

Direct investigation on the cardiovascular effects of wildfire smoke exposure; relatively straightforward availability of hospitalization records and air quality (mainly PM) data

Exposure misclassification; limited causal inference; difficult to capture subclinical cardiovascular changes; failure to consider the effects of gases (O₃, NO₂, etc) and VOCs from wildfire smoke

Epidemiological studies on household biomass smoke

29

26

Indoor biomass smoke exposure is associated with increased blood pressure, vascular dysfunction, circulating vascular markers, and cardiovascular morbidity and mortality

Study sites and length are not restricted to wildfire events; straightforward follow-up with subjects using household fuels; applicability of interventions; can study subclinical endpoints

Household biomass smoke is not equal to wildfire smoke; not ideal for causal inference, cannot account for real-world wildfire events

Intervention / controlled human exposure studies

15

11

There are significant changes in vascular function, blood pressure, HRV, circulating cardiovascular and inflammatory markers

Controlled exposure and environmental conditions; potential for causal inference; detailed smoke characterization; randomization and cross-over design

Wood smoke does not equal wildfire smoke; cannot account for other environmental conditions in the real world wildfire events; exposure time is relatively short

In vivo animal studies

7

6

At different extent, wood /peat smoke condensate cause cardiovascular dysfunction, and increase inflammatory and cardiovascular injury markers

Detailed wood smoke characterization; controlled dose and exposure duration; sound model to examine cardiovascular function; sound for mechanistic studies

Wood smoke does not equal wildfire smoke; difficult to generalize the information to human exposure; intratracheal aspiration as exposure method in some studies is different from inhalation

In vitro studies

9

8

Wood smoke extract can induce cytotoxicity, oxidative stress and altered levels of inflammatory and vascular markers

Detailed wood smoke characterization; controlled dose and exposure duration; sound for mechanistic studies

Wood smoke does not equal wildfire smoke; difficult to generalize the information to human exposure