Smog and mirrors

The aerosol scientist has spent decades scanning the air for invisible threats. A movement she led shaped WHO and global response to the spread of Covid-19. Morawska recently won Australia's Prime Minister's Prize for Science. Her focus is ultrafine particles. What we're breathing in really worries her, she says

- Sukanya Datta

It's like a giant ocean above our heads. It holds, like the oceans, a host of unanswered questions.

Among the ones that concern us most directly: What happens to what's in the air we breathe? How much gets into the bloodstream; what impact does it have?

Zooming out, more queries take shape: In what ways can the tiniest particles in the air affect monsoon patterns, or intensify storms? How do these aerosols affect disease transmission?

Lidia Morawska, 73, a Polish-Australian aerosol scientist, has been researching some of these questions for 35 years. Her area of focus is a particularly invasive component: ultrafine particles (UFP; smaller than the smallest particulate matter of 2.5 microns captured by air-quality monitors).

One pivotal movement she piloted changed how the World Health Organization (WHO), and the world, treated the Covid-19 virus amid the pandemic.

It wasn't just large droplets settling on surfaces that helped it spread. It wasn't just about doorknobs and communal furniture.

Microdroplets, light and small, were lasting far longer than existing calculations accounted for, she told WHO (Morawska has been an advisor to the global body since 1998). These were exhaled during breathing, talking and coughing, and were entering the respiratory systems of healthy people.

The physics of particle transmission is something Morawska began studying during the SARS (Severe Acute Respiratory Syndrome) epidemic of 2003. There was so little existing research, she says, that it brought home to her "how little we still know as a species".

By the time Covid-19 struck, the understanding was there, but not immediate acceptance.

"It was truly distressing to see advisories on washing hands but nothing on masks, early on; to see people step out to the supermarket in gloves but no masks," she says.