New research has raised questions over the manner in which we have been analysing the component parts of particulate matter, suggesting that the delays in testing samples are allowing a large amount of harmful substances to be missed.
The mystery of particulate matter’s health threat is knowing which parts of the PM are doing the damage.
For this research, a team from the Department of Environmental Sciences at the University of Basel focussed on the oxidative potential (OP) of particulate matter. OP can lead to oxidative stress which is linked to health problems such as asthma, COPD, heart disease and cancer. Oxidative stress occurs when there’s an imbalance between the production of reactive oxygen species (ROS) and the body’s ability to detoxify them.
Traditionally PM samples have been collected on filters and subsequently analysed in laboratories at a later date. It is this delay that the team believe has led to a considerable underestimation of the potentially harmful substances within the PM.
In order to speed up this analysis, the team developed a way of collecting particles directly from the air and analyse them immediately. Their method involved collecting the particles on a filter coated with a solution which reacts with any reactive oxygen species (ROS) in the particles. This mixture is then combined with chemicals to produce a fluorescent signal. The amount of fluorescence shows how much ROS is present.
Atmospheric scientist Professor Markus Kalberer explained the reasoning: ‘Since these reactive oxygen species [ROS] react with other molecules so quickly, they should be measured without delay.’
Using these fast, real-time tools they found that 60–99% of the harmful ROS in pollution lasts between a matter of minutes to a few hours. That means traditional methods, which collect particles for analysis at a later time, are missing a lot of this activity, seriously underestimating the pollution’s harmful effects.
The team conclude that: ‘The fast decay and, especially, the high variability of the short-lived OP fraction in a wide range of particles implies that online OP instruments, which use a direct-to-reagent sampling approach, should be included in future air monitoring networks, possibly in parallel with offline OP analyses. This will be crucial for identifying links of OPT with particle composition, toxicity, and health effects.’
The full research can be read here.