By: John E. Barnes

John E. Barnes — Mon, 27 Oct 2025 17:05:53 +0000

Hello M, you can divide the substances in the air into gases and aerosols. But there can be dozens of gases in the air, and several different kinds of aerosols (particles) that are made up of many components. Each state in the USA monitors a few gases like ozone, nitrogen oxides, and sulfur dioxide but only at a few locations. But monitoring these few gases can often indicate if other pollutant gases can be expected. The monitoring sites also measure Particle Mass like PM2.5 and PM10. But the instrument can’t tell what the particles are made of, that would require collecting particles on filters and analyzing them chemically. This is sometimes done but it is expensive. Sometimes measurement campaigns are organized by government, industry, and academic organizations and they measure many more of the pollution components. But these campaigns tend to be short-term. What gets monitored in countries other than the USA varies a lot, from monitoring similar to the USA to very little monitoring. But monitoring is growing with new inexpensive instruments becoming available. But then it is important for someone to look at the data with a scientific eye to see how accurate the data are. Instruments have to be calibrated in some way to have confidence in the measurements.

By: M

Tue, 21 Oct 2025 22:54:04 +0000

Hi,
In a situation of a person experiencing ongoing exposures to unknown substances in different locations, how can the substances and sources be identified?
Thank you,

Comments on: How can we see air pollution with a camera?

By: John E. Barnes

By: M