# Association Between Air Pollution and Monday Peak Mortality From Acute Myocardial Infarction

## TL;DR

This study found that increased heart attack deaths on Mondays in Spain are not caused by changes in air pollution levels.

## Contribution

The study is the first to investigate the role of air pollution in the Monday peak of heart attack mortality.

## Key findings

- AMI mortality peaks on Mondays with a 3.7% increase above the weekly average.
- PM2.5 and PM10 pollution levels rise from Sunday to Monday but do not explain the Monday mortality peak.
- Adjusting for pollution levels showed no modification of the Monday mortality pattern.

## Abstract

Mortality from acute myocardial infarction (AMI) exhibits a weekly pattern, with a peak occurring on Mondays. Although several hypotheses have been proposed, the effect of air pollution on this peak has not yet been investigated.

The purpose of this study was to investigate if daily variation in major air pollutants modifies the risk of AMI mortality on Monday.

A time-series study analyzed 260,320 AMI deaths in Spain from 2004 to 2018, using records from the Spanish National Institute of Statistics. Air pollution (ie, PM2.5, PM10, nitrogen dioxide, and ozone) levels were estimated across the mainland Spain and the Balearic Islands. Regression models and multilevel meta-analysis were used to assess the weekly variation in AMI mortality and the association between air pollution and the Monday excess in AMI mortality.

AMI mortality varied throughout the week, peaking on Monday (+3.7% above the weekly average). Particulate air pollution (PM2.5, PM10) also showed a weekly pattern, with lower levels on weekends than weekdays. A significant increase in PM2.5 and PM10 levels was observed from Sunday to Monday (12.6% and 12.0%, respectively), but not between other weekdays. After adjustment for inter-weekly baseline mortality changes, the intra-weekly pattern in AMI mortality was not modified by either the absolute level or the inter-day change in air pollutants. In addition, no association was found between air pollution and the Monday peak in AMI mortality.

Our results suggest that the excess AMI mortality observed on Mondays in the Spanish population is not explained by concurrent variations in major air pollutants.