AQHI tracked health risks better than AQI in central Taiwan

What the study found: The study found that the Air Quality Health Index (AQHI), which combines daily concentrations of PM2.5, ozone, and nitrogen dioxide, was a more sensitive short-term health-relevant measure than the conventional Air Quality Index (AQI) during pandemic-altered activity patterns.
Why the authors say this matters: The authors conclude that their findings provide empirical evidence supporting Taiwan's adoption of AQHI for risk communication and for protecting vulnerable populations.
What the researchers tested: The researchers examined PM2.5 chemical characteristics in Taichung, Taiwan, from 2020 to 2022, focusing on polycyclic aromatic hydrocarbons (PAHs) and water-soluble ions across industrial and traffic areas. They also analyzed AQHI-based health risks using outpatient records from 2016 to 2022, divided into pre-, during-, and post-pandemic stages.
What worked and what didn't: During pandemic restrictions, total water-soluble ion concentrations increased, largely because non-sea-salt sulfate rose in the industrial area. PAH concentrations declined during lockdowns but rebounded in the warm season after the pandemic, reaching about two to three times pandemic-stage levels; source analyses pointed to traffic-related emissions, especially diesel exhaust, as the dominant PAH source. High-risk AQHI levels (7 or above) were associated with increased respiratory and cardiovascular morbidity, while PM2.5 and NO2 showed acute and persistent risks and O3 showed delayed inverse statistical associations.
What to keep in mind: The abstract does not describe specific study limitations beyond the scope of the data, and the health findings are based on the study's statistical analyses and the time periods it examined.

Key points

• AQHI was reported as a more sensitive short-term health metric than AQI during pandemic-altered activity patterns.
• High-risk AQHI levels (7 or above) were associated with increased respiratory and cardiovascular morbidity.
• Water-soluble ion concentrations increased during pandemic restrictions, driven mainly by non-sea-salt sulfate in the industrial area.
• PAH concentrations declined during lockdowns and then rebounded after the pandemic, especially in the warm season.
• Traffic-related emissions, particularly diesel exhaust, were identified as the dominant contributors to ambient PAHs.