Health outcome · marker · measured in 10⁶/mL
Sperm count
Part of: Semen quality
Also: sperm concentration, total sperm count, oligospermia
The number of sperm in a semen sample, reported as a concentration per millilitre or as a total per ejaculate. It is the oldest and most reported measure of male fertility, and the one that reflects what happened during the roughly three months the sperm took to form.
Why it matters indoors
Count integrates a long exposure window. Sperm production takes about three months, so a sample measured today reports the conditions of the preceding season rather than of the preceding week — the opposite of motility, and the reason the two parameters can move independently in the same study.
That window is what makes the measure useful against household exposures, which are seasonal in exactly the same way: a heating season spent with an unvented appliance, or a period of cooking on solid fuel, covers the production of the sperm being counted.
Two things limit what a single figure can say. Within-person variation between samples is large, so studies that take one sample per man measure noise as well as signal; and abstinence time before the sample changes the count substantially, which is why protocols specify it. A result without that protocol detail is weak, and the caveat records whether it was given.
Indoor factors with evidence
| Factor | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Particulate matter (PM₂.₅ and PM₁₀) | SMD -0.036 (-0.06–-0.01) | men undergoing semen analysis | systematic review and meta-analysis of studies on ambient particulate matter and semen quality parameters (6264 participants in the included studies) | F-0226 Bahreiny Association between ambient particulate matter and semen qua… (2024) | machine |
| Particulate matter (PM₂.₅ and PM₁₀) | SMD -0.027 (-0.052–-0.02) | men undergoing semen analysis | systematic review and meta-analysis of studies on ambient particulate matter and semen quality parameters (6264 participants in the included studies) | F-0229 Bahreiny Association between ambient particulate matter and semen qua… (2024) | machine |
Each row is one Finding — a sentence as printed in one study, recorded with its page in the Coridum Knowledge Base. Follow the Finding number for the exact wording and the citation. Checked says who verified the row: machine means every automatic check passed and the surrounding text was read; person means someone read the sentence in the document. Rows are re-checked by a person over time. The studies are curated in the Coridum Knowledge Base; the reading of them together is a Claim, shown separately.
Cite this page
Coridum Research. Sperm count. Coridum Knowledge G-0176, 16 September 2026. https://coridum.com/k/G-0176/