www.who.int

The numbers

First visit

1.02 g CO₂e

Return visit

0.015 g CO₂e

Hosting

unknown

LCP

776 ms

CLS

0.016

TTFB

39 ms

At 10,000 views a month this page emits about 92.1 kg CO₂e a year, roughly 378 km in an average petrol car. The estimate assumes 75% new and 25% returning visitors, a measured cache reload ratio of 2%, and world-average grid intensity. How we calculate this

1. Audit third-party servicessave ~0.224 g/visit (2.01 MB)High impact · moderate effort

   19 third-party domains account for 4.02 MB (58% of the page).

   Remove services that no longer earn their place; load the rest on interaction (facades for embeds, delayed consent-gated tags). Each third party is also a privacy and performance dependency.

   • kendo.cdn.telerik.com2.35 MB
   • static.fundraiseup.com892 kB
   • www.googletagmanager.com345 kB
   • cdn.fundraiseup.com113 kB
   • use.fontawesome.com93 kB
   • fonts.googleapis.com65 kB

   WSG 3.5: Treat third parties the same as first parties
2. Convert and compress imagessave ~0.089 g/visit (800 kB)High impact · quick fix

   24 images (1.78 MB) ship in legacy formats (JPEG/PNG/GIF).

   Serve AVIF (or WebP) with responsive srcset sizes, and re-compress oversized files. AVIF typically halves JPEG weight at the same visual quality.

   • stag-ntd-illustration.tmb-768v.png269 kB
   • health-workers-during-ebola-response-dr-congo…206 kB
   • hiv-and-sti-prevention-and-treatment9752ebe4-…160 kB
   • noma-nigeria-2017-jeantet-claire-inediz.tmb-7…134 kB
   • lifeguard-training-in-ghana.tmb-768v.jpg132 kB

   WSG 2.9: Optimize media to reduce resource use
3. Reduce JavaScript payloadsave ~0.083 g/visit (744 kB)High impact · moderate effort

   51 scripts total 2.97 MB on the wire (10.71 MB decoded). Bundles this size usually carry a lot of unused code.

   Split bundles per route, tree-shake dependencies, and audit with a bundle analyzer or coverage profile. A 25% cut is a conservative target for bundles this size.

   • kendo.all.min.js1.14 MB
   • checkout.596224d868c89ea0.js449 kB
   • gtm.js175 kB
   • js170 kB
   • elements-langs-vendors.79b64f6e3c1f5557.js153 kB

   WSG 3.2: Minify and remove unused codeWSG 3.3: Modularize bandwidth-heavy components
4. Fix caching for returning visitorssave ~0.0033 g/visit (22 kB)Medium impact · quick fix

   On a repeat visit 89 kB of static assets were re-downloaded instead of coming from cache.

   Serve static assets with Cache-Control: public, max-age=31536000, immutable and versioned filenames so returning visitors download almost nothing.

   • AMEEWKFZ.jsno Cache-Control header · 46 kB
   • ScriptResource.axdCache-Control: public, max-age=0, s-maxage=86400 · 6.6 kB
   • WebResource.axdCache-Control: public, max-age=0, s-maxage=86400 · 6.6 kB
   • ScriptResource.axdCache-Control: public, max-age=0, s-maxage=86400 · 6.6 kB
   • ScriptResource.axdCache-Control: public, max-age=0, s-maxage=86400 · 6.6 kB

   WSG 4.2: Optimize caching and support offline access
5. Verify your hosting energyMedium impact · moderate effort

   This host has not published renewable energy evidence with the Green Web Foundation, so its energy source is unknown.

   Choose a provider listed in the Green Web Directory, or ask your current provider to publish evidence (and a carbon.txt). This cuts the data-center share of every single page view.

   • carbon.txtNo carbon.txt found at the site root; publishing one is the lightest first step.

   WSG 4.1: Use sustainable hosting
6. Stop downloading the same asset twicesave ~0.065 g/visit (584 kB)Advisory · quick fix

   5 assets were fetched more than once in a single page load (1.38 MB of repeated transfer).

   Usually a script injected twice or cache-busting query strings that differ per reference. Load each asset once and let the HTTP cache do its job.

   • h-logo-blue1820eae93c154e37b2588ab90fdbc17e.svg8 downloads · 108 kB
   • h-logo-blue.svg9 downloads · 121 kB
   • kendo.all.min.js2 downloads · 2.27 MB
   • kendo.timezones.min.js2 downloads · 77 kB
   • tb2 downloads · 750 B

   WSG 3.2: Minify and remove unused code
7. Upgrade compression beyond gzipsave ~0.059 g/visit (529 kB)Advisory · quick fix

   3.52 MB of text ships gzip-compressed; Brotli or Zstandard would cut roughly another 15-20%, and browsers without them fall back to gzip automatically.

   Serve precompressed Brotli for static text assets (highest level, compressed at build time) and enable Brotli or zstd for dynamic responses; keep gzip only as the fallback.

   • kendo.all.min.js1.14 MB
   • kendo.all.min.js1.14 MB
   • main.min.css331 kB
   • ScriptResource.axd97 kB
   • origin.min.css73 kB

   WSG 4.3: Reduce data transfer with compression
8. Optimize web fontssave ~0.0059 g/visit (53 kB)Advisory · quick fix

   4 font files total 151 kB.

   Subset fonts to used glyphs, prefer one variable font over multiple weights, serve WOFF2 only, and consider system fonts for UI text.

   • fa-solid-900.woff279 kB
   • o-0bIpQlx3QUlC5A4PNB6Ryti20_6n1iPHjc5a7duw.woff236 kB
   • o-0bIpQlx3QUlC5A4PNB6Ryti20_6n1iPHjc5ardu2ui.…20 kB
   • ibmplexsans-v19-latin-600.afba6ba6bf9157e8.woff216 kB

   WSG 2.11: Use optimized web typography
9. Set a page-weight budgetAdvisory · moderate effort

   At 6.87 MB per view this page rates F. The findings above list where the weight is.

   Agree a transfer budget (e.g. under 975 kB reaches a B), enforce it in CI, and re-scan after each change to hold the line.

   WSG 3.1: Set goals based on performance and energy impact
10. Remove the entry redirectAdvisory · quick fix

    The address that was scanned goes through 1 redirect before the document is served, ending at https://www.who.int/. Every hop is a full round trip on a connection that has not warmed up yet.

    Point links, sitemaps and canonical tags at the final address, and make the host redirect in one hop rather than chaining http to https to www.

    • https://who.int/redirects to https://www.who.int/

    WSG 4.4: Setup necessary error pages and redirection links
11. Simplify the document structureAdvisory · larger effort

    The page renders 2238 DOM elements, above the 1,500 guideline. Large trees cost memory and CPU on every visitor's device.

    Flatten wrapper markup, render long lists virtually or paginate, and prefer semantic elements over nested divs.

    WSG 3.6: Ensure code follows good semantic practices

Where the bytes are

• JavaScript2.97 MB · 51 req
• Images1.86 MB · 35 req
• Other1.17 MB · 2 req
• CSS500 kB · 10 req
• Data (XHR)183 kB · 17 req
• Fonts151 kB · 4 req
• HTML31 kB · 1 req
• Data (fetch)750 B · 4 req