Table 1.

A summary of the main challenges in comparing emissions across tobacco products and some recommendations to standardize the comparison

Challenges	Recommendations
Sample generation	Use the same smoking/vaping machine to conduct testing across products if possible. Cross-validate different smoking/vaping machines if needed. Develop universal leak-free smoking/vaping machine adaptors that fit different tobacco product mouth ends.
Puffing conditions	Report all puffing/sampling conditions. Develop product-specific puffing regimes using data collected from clinical and epidemiological studies. Standardize the smoking/vaping session length across products based on a common parameter (e.g. nicotine yield).
Product-specific sampling conditions	Mimic actual use of products when testing in the lab (e.g. preheating). Develop reference products for all types of tobacco products.
Techniques of aerosol trapping	Optimize aerosol/smoke trapping methods to account for the specificity of each product (e.g. liquid or solid particles, difference in analyte levels across products, and partitioning of analytes between particle and gas phases). Cross-validate different trapping methods if needed.
Analytical method suitability	Optimize analytical methods to account for different matrices and constituent levels across products. Cross-validate different analytical methods if needed.
Particle size distribution	Optimize analytical methods and techniques used to characterize particles in the aerosol of different tobacco products. Optimize the conditions to collect particles from different products with minimum perturbance of the particles. Cross-validate different particle size distribution methods if needed.
Toxicants to monitor	Update the priority lists of toxicants to reflect exposure from new and emerging products (e.g. the FDA HPHC list). Generate more inhalation toxicity data on compounds found in tobacco emissions. Conduct non-targeted analysis of emissions from new and emerging products.
Data reporting	Report data on a comparable metric across products (e.g. mass per total puff volume). Report data standardized to nicotine yield.
Statistical power	Balance statistical power with the length of the list of toxicants to compare across products. Use newly developed tools of risk assessment to prioritize toxicants for comparison.