---
title: "Sulfur Dioxide — AP Enviro Definition & Exam Guide"
description: "Sulfur dioxide (SO2) is a gas released mainly by burning coal. It causes acid rain and respiratory problems, linking AP Enviro Units 6 and 7 on the exam."
canonical: "https://fiveable.me/ap-enviro/key-terms/sulfur-dioxide"
type: "key-term"
subject: "AP Environmental Science"
---

# Sulfur Dioxide — AP Enviro Definition & Exam Guide

## Definition

Sulfur dioxide is a gas that is released into the atmosphere through the burning of fossil fuels, particularly coal and oil. It contributes to air pollution and can cause respiratory issues in humans.

## Related Study Guides

- [7.2 Photochemical Smog](/ap-enviro/unit-7/photochemical-smog/study-guide/PWfwfAuylO1PBZeNUKkD)
- [6.5 Fossil Fuels](/ap-enviro/unit-6/fossil-fuels/study-guide/ZPox55JnXjW1F0PkOaXR)

## Review

### Related Terms

- [Acid Rain](/ap-enviro/key-terms/acid-rain): Acid rain is formed when sulfur dioxide combines with water vapor in the atmosphere, creating acidic precipitation that can harm ecosystems.
- [Particulate Matter](/ap-enviro/key-terms/particulate-matter): Particulate matter refers to tiny particles suspended in the air, which can include sulfur dioxide. These particles can have negative health effects when inhaled.
- [Fossil Fuels](/ap-enviro/key-terms/fossil-fuels): Sulfur dioxide is primarily emitted from burning fossil fuels such as coal and oil. Understanding fossil fuels helps us grasp where sulfur dioxide comes from.