Recent spikes in the concentration of PM2.5 air pollutants over wide areas of Japan have once again raised alarms over the health risks from the small particles. While increases in PM2.5 levels are often linked to pollutants drifting over from China, there are also domestic sources that warrant further study and coordinated cross-border action.
According to the Environment Ministry, the daily average concentration of PM2.5 in eight prefectures — Fukushima, Niigata, Toyama, Ishikawa, Fukui, Osaka, Hyogo and Kagawa — exceeded 70 micrograms per cubic meter on Feb. 26, setting off an alert under the government's provisional guidelines. Local municipalities urged people to wear masks and avoid heavy exercise outdoors.
PM2.5 particles measure up to 2.5 microns, or 0.0025 millimeter, in diameter. These fine particulates can easily penetrate the lungs, causing asthma or raising the risk of lung cancer. They are also linked to arrhythmia, an irregular heartbeat condition.