diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6a1e33938a..b69cbbf7e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- `opentelemetry-sdk`: Clarify timeout units in environment variable documentation
+  ([#4906](https://github.com/open-telemetry/opentelemetry-python/pull/4906))
 - `opentelemetry-exporter-otlp-proto-grpc`: Fix re-initialization of gRPC channel on UNAVAILABLE error
   ([#4825](https://github.com/open-telemetry/opentelemetry-python/pull/4825))
 - `opentelemetry-exporter-prometheus`: Fix duplicate HELP/TYPE declarations for metrics with different label sets
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py
index ae3959ef15..420b576c86 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/environment_variables/__init__.py
@@ -247,7 +247,7 @@
 """
 .. envvar:: OTEL_EXPORTER_JAEGER_TIMEOUT
 
-Maximum time the Jaeger exporter will wait for each batch export.
+Maximum time (in seconds) the Jaeger exporter will wait for each batch export.
 Default: 10
 """
 
@@ -334,7 +334,7 @@
 """
 .. envvar:: OTEL_EXPORTER_OTLP_TIMEOUT
 
-The :envvar:`OTEL_EXPORTER_OTLP_TIMEOUT` is the maximum time the OTLP exporter will wait for each batch export.
+The :envvar:`OTEL_EXPORTER_OTLP_TIMEOUT` is the maximum time (in seconds) the OTLP exporter will wait for each batch export.
 Default: 10
 """
 
@@ -682,16 +682,18 @@ def channel_credential_provider() -> grpc.ChannelCredentials:
 """
 .. envvar:: OTEL_EXPORTER_OTLP_TRACES_TIMEOUT
 
-The :envvar:`OTEL_EXPORTER_OTLP_TRACES_TIMEOUT` is the maximum time the OTLP exporter will
+The :envvar:`OTEL_EXPORTER_OTLP_TRACES_TIMEOUT` is the maximum time (in seconds) the OTLP exporter will
 wait for each batch export for spans.
+Default: 10
 """
 
 OTEL_EXPORTER_OTLP_METRICS_TIMEOUT = "OTEL_EXPORTER_OTLP_METRICS_TIMEOUT"
 """
 .. envvar:: OTEL_EXPORTER_OTLP_METRICS_TIMEOUT
 
-The :envvar:`OTEL_EXPORTER_OTLP_METRICS_TIMEOUT` is the maximum time the OTLP exporter will
+The :envvar:`OTEL_EXPORTER_OTLP_METRICS_TIMEOUT` is the maximum time (in seconds) the OTLP exporter will
 wait for each batch export for metrics.
+Default: 10
 """
 
 OTEL_EXPORTER_OTLP_METRICS_INSECURE = "OTEL_EXPORTER_OTLP_METRICS_INSECURE"
@@ -724,8 +726,9 @@ def channel_credential_provider() -> grpc.ChannelCredentials:
 """
 .. envvar:: OTEL_EXPORTER_OTLP_LOGS_TIMEOUT
 
-The :envvar:`OTEL_EXPORTER_OTLP_LOGS_TIMEOUT` is the maximum time the OTLP exporter will
+The :envvar:`OTEL_EXPORTER_OTLP_LOGS_TIMEOUT` is the maximum time (in seconds) the OTLP exporter will
 wait for each batch export for logs.
+Default: 10
 """
 
 OTEL_EXPORTER_JAEGER_CERTIFICATE = "OTEL_EXPORTER_JAEGER_CERTIFICATE"