How Polluted Air Wipes Out The Benefits Of Exercise

…and other items from this week’s health science news:

This may take the wind out of things

It is not shocking news that air pollution is not good for the health. In terms of PM2.5 levels (that is to say, the density of particulate matter than 2.5 micrometers), once annual PM2.5 reaches 25 μg/m³, the risk-reduction effect of exercise falls dramatically; 46% of the world lives at or above this level, and in the US, it’s nearer 50%.

As for how dramatic that dramatic fall is, let’s put it in numbers: people achieving at least two and a half hours of moderate or vigorous exercise each week normally see a 30% lower mortality risk, but this shrinks substantially in polluted regions, down to 12–15%.

Worse, and beyond just the effects of exercise, once yearly PM2.5 exceeds 35 μg/m³, the benefits weaken further, and cancer-related deaths rise further too—the mechanism of action here being that exercise’s anticancer effects are significantly reduced. That’s not a guess, by the way—statistical modelling was used to establish it.

Dr. Paola Zaninotto, of the Department of Epidemiology & Public Health, when asked for comment, advised that people should keep exercising outdoors but can maximize benefits by checking air quality, choosing cleaner routes, or reducing intensity at more polluted times.

Read in full: Polluted air quietly erases the benefits of exercise

Related: Half of the US has dangerously polluted air

Watch out for cannabis hyperemesis syndrome

Cannabis hyperemesis syndrome is the official name for what has long been known in ER wards by the more colorful unofficial name “scromiting“—a portmanteau of screaming and vomiting.

It’s not fun.

It now has a new ICD-10 code, R11.16, which lets clinicians document cannabis hyperemesis syndrome consistently, which is important for the kind of stats that ultimately fuel the onwards march of science.

Still, there’s an element of reporting bias (i.e. a lot goes unreported), and intermittent symptoms can cause people to misinterpret flare-ups as unrelated events. Plus, even when the diagnosis is accepted, addiction can make stopping cannabis use—and therefore preventing future episodes—difficult too.

Some patients doubt the diagnosis because cannabis is widely considered to relieve nausea, and for some people in some circumstances, it may.

So far, it’s also been tricky to treat: standard anti-nausea drugs often fail; clinicians sometimes rely on medications like Haldol, or supportive measures such as hot showers and topical capsaicin cream, which some patients apply to their abdomen during episodes.

There’s a lot that’s not known about the mechanism of action, and the reasons some long-term cannabis users develop the syndrome remain unclear, with possibilities including changing THC potency or increasing availability, or even that there is some cumulative damage that is contributing to an eventual vulnerability.

Read in full: Why more cannabis users are landing in the ER with severe vomiting

Related: Cannabis Myths vs Reality

When acne is hard to spot

Researchers (Dr. Anni Telkkälä et al.) recently found that around 31% of 35-year-old Finnish women have acne on the face or back, but many do not realize they have it. In the study, dermatologists identified acne in far more participants than those who self-reported symptoms.

In terms of where the acne was showing up, facial acne affected 26% of women, particularly the chin and cheeks. Meanwhile, back acne was found in 12%, and 6% had both facial and back acne. Notably, this underdiagnosis meant that both over-the-counter and prescription treatments were used sparingly.

Which is unfortunate, as to quote Dr. Suvi-Päivikki Sinikumpu, another researcher on the team,

❝Even mild acne can significantly affect well-being and mood, and adult acne has been shown to have an even greater impact on quality of life than teenage acne.

The results show that acne is not confined to the face, as back acne is surprisingly common. Skin changes on the back may be mistaken for harmless heat spots, even though they are often acne.

Both facial and back acne can lead to permanent scarring if left untreated.❞

Read in full: Study reveals widespread unrecognized acne among 35-year-old Finnish women

Related: Dealing With Back Acne

Take care!